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  • Articles  (4,417)
  • Chemistry  (4,417)
  • Fluid Mechanics and Heat Transfer
  • Inorganic Chemistry
  • 1995-1999  (4,417)
  • 1950-1954
  • 1997  (1,365)
  • 1996  (3,052)
  • Physics  (4,417)
  • 1
    Electronic Resource
    Electronic Resource
    Turbulent mixing of reactive gases in the convective boundary layer (1997)
    Springer
    Boundary layer meteorology 85 (1997), S. 197-222 
    Details
    ISSN: 1573-1472
    Keywords: Turbulence ; Chemistry ; Closure ; Convective boundary layer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We study the interactions of chemistry and turbulent mixing of tracersin the convective boundary layer with a second-order closure model,including higher order chemistry terms. In order to limit the number of predictive equations we prescribe the profiles for ¯w¯Θ, ¯w¯θ ¯θ and the lengthscale l. However, for model validation we treat temperature and humidity asinert tracers, and compare the results with profiles observed during theAir Mass Transformation Experiment, and with similarity expressions for thesurface layer. We find good agreement of the mean profiles, but the (co-)variances are slightly underpredicted. Furthermore, the model usesdiagnostic equations expressing third moments of concentration in terms ofsecond moments and their vertical derivatives. They are compared withlarge-eddy model results, showing good agreement and, therefore, thesimplifications are justified. The model is applied to the transport of two gases subject to one bimolecular reaction. The importance of concentration correlations on themean transformation rate is studied. For two gases diffusing in oppositedirections we find for moderate and fast chemistry a 50% and90% decreased transformation rate due to the negatively correlatedconcentrations. These values are similar to large-eddy results of Schumannand Sykes et al. For two bottom-up tracers we find that the covariance ofboth reactive species is either positive or negative, increasing or reducingthe effective transformation rate depending on the Damköhler number (the ratio of the turbulent and the chemistry timescale). A significantdirect influence of chemistry on the flux divergence is found in bothcases. According to the model the effective transport to mid-levels of theboundary layer is increased when two reactive tracers diffuse in oppositedirections, and decreased in the case of two bottom-up tracers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1000414710372
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  • 2
    Electronic Resource
    Electronic Resource
    Polycarbonat-ein vielseitiger werkstoff mit zukunft (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 244 (1997), S. 43-66 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The market development of bisphenol-A-polycarbonate has shown higher growth than any other engineering thermoplastic. The reasons can be found in the permanent improvement of the cost/performance-relationship and in the technical use of the variability of the basic structure. Incorporation of specific monomer units leads to tailor-made properties for a wide range of applications, as for example medical devices, electronic parts and glazing.This process has not yet slowed down, rather it is accelerated by new results from research and development. The improvement of flaw behavior and pit replication for new grades of materials for the next generation of compact discs, new grades that can be sterilized by γ-radiation without degradation and the microstructuring by low-energy laser systems are examples for the ongoing expansion of polycarbonate applications. Surface modification by hardcoatings with nanosized particles will allow to enter the fast growing market of glazing.
    Additional Material: 27 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052440103
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  • 3
    Electronic Resource
    Electronic Resource
    Polyamide, polyester und polyoxymethylen. Die klassischen technischen kunststoffe und ihre perspektiven (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 244 (1997), S. 67-92 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polyamide, Polyester und Polyoxymethylen sind mit einem weltweiten Verbrauch von derzeit 2,4 Mio t pro Jahr wichtige technische Kunststoffe. Sie werden aufgrund ihrer besonderen Eigenschaftsprofile überwiegend im Fahrzeugbau und in der Elektroindustrie für hochbelastete Funktionsbauteile eingesetzt. Der vorliegende Beitrag behandelt Polymerisationswege, Eigenschaften und ausgewählte neue Entwicklungen dieser Polymerklassen.Teilaromatische Polyamide stoßen durch ihre Dimensionsstabilität und thermische Belastbarkeit in Anwendungen vor, die bisher Duromeren oder Metallen vorbehalten waren. Glasfaserverstärkte Polyamide mit besonders hoher Dauerwärmebeständigkeit übemehmen wichtige Funktionen im Motorbereich von Fahrzeugen. Polyamid-Blends sind als Karosseriewerkstoffe ein Schlüssel zu leichten Autos mit niedrigem Treibstoffverbrauch. Halogenfrei flammgeschützte Polyamide erhöhen Sicherheit und Umweltverträglichkeit in brandgefährdeten Anwendungsbereichen.Polybutylenterephthalat als technisch wichtigster Polyester eröffnet in Mischung mit amorphen Polymeren neue Perspektiven durch geringerenVerzug und bessere Oberfläche bei glasfaserverstärkten Teilen. Polybutylennaphthalat erweitert den Anwendungsbereich zu höheren Temperaturen. Von Polybutylenterephthalat abgeleitete Copolyester sind biologisch abbaubar und daher vielversprechend für kompostierbare Folien.Polyoxymethylen-Copolymere haben ihre Stärke in der günstigen Kombination aus Steifigkeit, Dimensionsstabilität, Gleit/Reibe-Verhalten und Beständigkeit gegen heißes Wasser und Kraftstoff.Aufgrund ihres hohen und noch weiter steigerungsfähigen Leistungsvermögens werden Polyamide, Polyester und Polyoxymethylen das in den letzten Jahren gezeigte Wachstum in Zukunft weiter ausbauen können.
    Notes: Polyamide, polyester and polyoxymethylene having presently a worldwide sales volume of 2,4 million tons a year are important engineering thermoplastics. Based on their special property profiles they are mainly used in the automotive and electronic industry for high performance functional parts. This contribution presents polymerisation processes, properties, and selected new developments for these polymer classes.Semiaromatic polyamides due to their dimensional stability and thermal resistance lend themselves to applications which were so far reserved for thermosets or metals. Glass fiber reinforce polyamides designed to have the highest possible heat ageing resistance can take important functions under the hood. A polyamide blend used as a material for exterior body parts is key to light weight cars with strongly reduced fuel consumption. Halogene free flame retardant polyamide increases fire safety and environmental safety in flame sensitive applications.Polybutyleneterephthalate as the technically most important polyester offers new perspectives in blends with amorphous polymers leading to lower distortion and better surface quality in glass fiber reinforced parts. Polybutylenenaphthalate is widening the range of application of polyesters towards higher temperatures. Copolyesters derived from polybutyleneterephthalate are biologically degradable and are therefore promising materials for fermentable foils.Polyoxymethylene copolymers show an outstanding combination of stiffness, dimensional stability, friction and wear as well as resistance against hot water and fuel.As a result of their excellent properties and the existing potential for further improvements polyamide, polyester and polyoxymethylene will continue to grow above average in the future.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052440104
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  • 4
    Electronic Resource
    Electronic Resource
    Sind polyurethanwerkstoffe ein reifes gebiet? (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 244 (1997), S. 121-133 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The world-wide production of polyurethanes has exceeded 6 mio. metric tons in 1994. Compared with the produced amounts of large-scale thermoplastics such as PE, PVC, PP and PS, polyurethanes keep the 5th place.Polyurethanes (PUR) are segmented polymers, which can be synthesized from preformed building blocks in a modular unit construction system. The chemical modules and the various possibilities of combination will be discussed here.Tailor-made polyurethane materials can be divided into two main-fields of application: foams and compact PUR.The main constituents of polyurethane materials are diisocyanates and polyols. These key- chemicals are well characterised with respect to their technological, economical and ecological properties. Taking into account the availability, the masses of production and the experiences that have been collected with the PUR main constituents, these PUR precursors seem to be very mature already.In contrast to this, the PUR-materials made from these building blocks still offer numerous novel problem-solutions, resulting from the variability of the diisocyanate-poly-addition reaction: PUR materials are most commonly segmented into several phases. The formation of hard- and softsegments can be easily demonstrated by looking at thermoplastic polyurethanes (TPU). A deeper understanding of this phase separation and the molecular organisation within these materials promises to realize prospectic polymeric architectures with new and improved properties. PUR materials will still be able to offer new answers to future requirements in balancing economical and ecological needs. By looking at the life-cycles of soft and hard-foams, polyurethane-coatings and thermoplastic PUR-elastomers, this contribution will adress the question: “Is PUR-chemsitry still a challenging field?”
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052440106
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  • 5
    Electronic Resource
    Electronic Resource
    Fire-retardant action of potassium nitrate in polyamide 6 (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 245 (1997), S. 23-35 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Zugabe von 10-20 Gew.-% Kaliumnitrat (KN03) zu Polyamid 6 (PA 6) vermindert die Brennbarkeit des Polymeren. Das thermische Verhalten der KN03/PA 6-Mischung wurde mittels Thermogravimetrie, Differentialkalorimetrie und Analyse der fluchtigen Anteile untersucht. Feste Zersetzungsprodukte der Mischung wurden mittels Infrarotspektroskopie, Rontgendiffraktometrie und Elektronenresonanzspek-'troskopie analysiert. Es wurde gefunden, daß KNO3 dem Flielßen und Tropfen der Schmelze vorbeugt und die Karbonisierung auf der Oberflache des Polymeren fordert. Das verringert die Brandgefahr und verbessert die Feuerbestandigkeit. Andererseits geht KNO3 mit PA 6 in der kondensierten Phase eine exotherme Reaktion ein und setzt Sauerstoff frei, der wiederum die Brennbarkeit von PA 6 begiinstigt. Der Mechanismus der chemischen Wechselwirkung van KNO3 mit PA 6 wird diskutiert.
    Notes: The addition of 10-20 wt.-% of potassium nitrate (KNO3) to polyamide 6 (PA 6) improves the fire retardance of the polymer. The thermal decomposition behaviour of the PA 6/KN03-mixture was studied using thermogravimetry, differential scanning calorimetry and thermal volatilisation analysis. Solid products of the thermal decomposition of the mixture were analysed by infrared spectroscopy, X-ray diffraction and electron paramagnetic resonance. It was found that KNO, prevents flowing and dripping of the melt and promotes charring on the surface of the polymer which decreases its fire hazard and improves its fire retardance. On the other hand, KNO3 exothermally reacts with PA 6 in the condensed phase and supplies oxygen to the gas phase which increases the combustibility of PA 6. The mechanism of the chemical interaction of KN03 with PA 6 is discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052450103
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of tricalcium phosphate, hydroxyethyl methacrylate, and ethylene glycol dimethacrylate on the mechanical properties of acrylic bone cement (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 245 (1997), S. 49-62 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß einer Beimischung von Tricalciumphosphat (TCP), Hydroxyethylmethacrylat (HEMA) und Ethylenglycoldimethacrylat (EGDMA) auf die Eigenschaften eines chirurgischen Knochenzements wurde untersucht. Die in Zugversuchen entstandenen Bruchflächen wurden mittels Rasterelektronenmikroskopie charakterisiert. Der Einfluß der Additive auf den Temperaturanstieg während der Polymerisation wurde geprüft. Zug-, Biege- und Druckfestigkeit des ausgehärteten Zements nahmen mit zunehmendem TCP-Gehalt ab, der Elastizitätsmodul stieg dagegen an. Die Zugfestigkeit nahm mit steigendem HEMA-Gehalt geringfügig zu und blieb oberhalb 15 Gew.-% HEMA konstant. Zug-, Biege- und Druckfestigkeit zeigten bei einem EGDMA-Gehalt von 2 Gew.-% (in HEMA) ein Maximum. HEMA und EGDMA beschleunigten die Polymerisation, wogegen TCP retardierend wirkte.
    Notes: The effects of the addition of tricalcium phosphate (TCP), hydroxyethyl methacrylate (HEMA), and ethylene glycol dimethacrylate (EGDMA) on the properties of standard surgical Simplex-P radiopaque bone cement have been investigated. The fracture surface after tensile test was studied by scanning electron microscopy. The influence of these components on the temperature rise during polymerization was investigated. It was found that the tensile strength, the bending strength, and the compressive strength decreased with increasing TCP content, whereas the inverse was observed for the Young's modulus. The tensile strength slightly increased with increasing HEMA content and then it levelled off when the HEMA content was higher than 15 wt.-%. It seemed that there were maximum tensile, bending and compressive strengths when 2 wt.-% EGDMA (in HEMA) was added. Polymerization occurred more rapidly when HEMA and EGDMA were added, whereas the inverse result was found with TCP.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052450105
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  • 7
    Electronic Resource
    Electronic Resource
    The relative physical and thermal properties of polyurethane elastomers. Effect of chain extenders derived from dihydroxynaphthalene (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 245 (1997), S. 89-104 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polyurethanelastomere wurden in Gegenwart von zwei Dihydroxynaphthalin(DHN)-Verbindungen und deren bromierter Derivate als Kettenverlängerer hergestellt. Als Polyole wurden Polycaprolactondiol und Polytetramethylenglykol und als Diisocyanat-Komponenten Diphenylmethandiisocyanat (MDI) und Dicyclohexylmethan-4,4′-diisocyanat (HMDI) eingesetzt. Der Einfluß der Struktur der Kettenverlängerer auf die physikalischen und thermischen Eigenschaften der Polyurethane wurde untersucht. Wegen der besseren Phasenmischungswirkung der 1,5-DHN-Segmente haben die damit hergestellten Polyurethane höhere Glasübergangstemperaturen und bessere dynamische Eigenschaften als die Polyurethane auf 2,7-DHN-Basis. Der Einbau von bromierten DHN-Einheiten erschwert die Entflammbarkeit. Durch das große freie Volumen der Bromatome wird jedoch die Rotation der DHN-Einheiten eingeschränkt, was zu Polyurethanen mit verringerten Phasenmischungs- und Kristallisationsgraden führt. Die bromhaltigen Polyurethane zeigen zudem eine Verschlechterung der mechanischen und physikalischen Eigenschaften und eine erhöhte Löslichkeit.
    Notes: Polyurethane elastomers were synthesized based on polyols such as poly(caprolactonediol) and poly(tetramethylene glycol), diisocyanates such as diphenylmethane-4,4′-diisocyanate (MDI) and dicyclohexylmethane-4,4′-diisocyanate (HMDI), and two dihydroxynaphthalenes (DHNs) and their brominated derivatives used as chain extenders. The effects of the chemical structures of the chain extenders on the physical and thermal properties of the polyurethanes were investigated. Because of the higher degree of phase mixing of the 1,5-DHN unit, the 1,5-DHN-based polyurethanes have higher Tg values and higher dynamic properties than 2,7-DHN-based polyurethanes. Introduction of bromine atoms increased the flame retardance. However, the large free volume of bromine atoms restricted the rotation of DHNs, thus, directly decreasing the degree of phase-mixing and crystallinity of the polyurethanes. Introducing bromine atoms also decreased the mechanical and dynamic properties and increased the solubility of the polyurethanes.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052450108
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of polypyrrolepolyurethane cationomer composites (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 245 (1997), S. 139-147 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aus Poly(oxytetramethylen), 4,4′-Bibenzyldiisocyanat, N-Methyldiethanolamin als Kettenverlängerer und Acrylsäure/Polyacrylsäure als Quaternisierungsagens wurden Poly(etherurethan)-Kationomere hergestellt. In aus diesen Kationomeren hergestellten Filmen wurde Pyrrol (15 Gew.-%) in Gegenwart von CuCl2 polymerisiert. Die Filme wurden mittels dynamisch-mechanischer Analyse, Thermogravimetrie und Differentialthermoanalyse charakterisiert. Die elektrische Leitfähigkeit beträgt für den Film ohne Polypyrrol 7.5 · 10-12 Ω-1 cm-1 und mit Polypyrrol 4.5 · 10-6 Ω-1 cm-1.
    Notes: Poly(ether urethane) cationomers based on poly(oxytetramethylene), 4,4′-bibenzyldiisocyanate, N-methyldiethanolamine as chain extender, and acrylic acid/poly(acrylic acid) as quaternization agent were synthesized. Pyrrole (15 wt.%%) was polymerized in films of the ionomer containing CuCl2. The films were characterized by dynamic mechanical analysis, thermogravimetry and differential scanning calorimetry. The electric conductivity of the film without polypyrrole is 7.5 · 10-12 Ω-1 cm-1, while incorporation of polypyrrole increases the conductivity to 4.5 · 10-6 Ω-1 cm-1.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052450112
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis, characterization and polymerization of waxy monomers (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 245 (1997), S. 155-164 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Wachsartige Monomere und Vernetzer wurden aus kommerziellen Wachsen durch Veresterung mit 2-Hydroxyethylmethacrylat, Glycerindimethacrylat oder Glycidylmethacrylat oder durch Funktionalisierung mit 2-Isocyanatoethylmethacrylat synthetisiert. Die erhaltenen opaken Methacrylate mit Schmelzpunkten zwischen 45 und 80°C wurden in Substanz bzw. Toluollösung in Gegenwart von Radikalinitiatoren polymerisiert. Die Polymeren zeichnen sich durch eine breite Molmassenverteilung aus. Im Gegensatz zur Substanzpolymerisation ist der Doppelbindungsumsatz nach der Lösungspolymerisation nahezu vollständig. Aufgrund der hohen Molmasse der Monomeren ist der beobachtete Polymerisationsschrumpf sehr gering. Polymerisate mit Vernetzermonomeren zeigen eine verbesserte mechanische Stabilität.
    Notes: Waxy monomers and crosslinkers, respectively, were synthesized from commercially available waxes by esterification with 2-hydroxyethyl methacrylate, glycerol dimethacrylate, or glycidyl methacrylate or by functionalization with 2-isocyanatoethyl methacrylate. The resulting opaque methacrylates with melting points between 45 and 80°C were polymerized in bulk and in toluene solution in presence of free radical initiators. The obtained polymers were characterized by a broad molecular weight distribution. Opposite to the bulk polymerization, the double bond conversion in solution polymerization is nearly quantitative. The observed volume shrinkage during polymerization is very low due to the high molecular weight of the monomers. Polymerizates containing crosslinking comonomers exhibit improved mechanical stability.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052450114
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  • 10
    Electronic Resource
    Electronic Resource
    Zur Kinetik der stabilisierten Fällungs-polymerisation eines Kationischen Monomeren in wäßrigen Natriumchlorid-Lösungen (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 245 (1997), S. 165-181 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The stabilized free-radical precipitation polymerization of the cationic monomer N-(2-methacryloyloxyethyl)-N,N-dimethylbenzylammonium chloride (MADAMBQ) in aqueous solutions of sodium chloride was studied by reaction calorimetry. Poly(ethylene oxide) was used as stabilizer. The rate of polymerization reaches its maximum immediately after initiation and remains nearly constant up to 50 % conversion followed by a decrease that could be described by a first order kinetics. The particles formed are approximately 1 to 30 μm in diameter and are stable over a period of several months.A model based on the theory of homogeneous particle nucleation is suggested to describe the kinetic course of polymerization, taking into account the rate of polymerization in both phases. With the assumption that the concentration of monomer in the phases is determined by a Nernst distribution law, the kinetics of the early stage of polymerization can be modelled reasonably well.The solution polymerization and the unstabilized precipitation polymerization of MADAMBQ was also studied.
    Notes: Die Kinetik der stabilisierten Fällungspolymerisation des kationischen Monomeren N-(2-Methacryloyloxyethyl)-N,N-dimethylbenzylammoniumchlorid (MADAMBQ) in wäßrigen Natriumchlorid-Lösungen wurde mittels Reaktionskalorimetrie untersucht. Polyethylenoxid höherer Molmasse wurde als Stabilisator eingesetzt. Die Reaktionsgeschwindigkeit ist über einen größeren Umsatzbereich nahezu konstant und fällt anschließend mit dem Umsatz annähernd linear ab. Die Teilchengrößenverteilung der gebildeten Dispersion ist bimodal mit Teilchen von etwa 1 bis 30 μm Durchmesser.Zur Beschreibung des Geschwindigkeitsverlaufs der Fällungspolymerisation wird ein Modell vorgeschlagen, das die Polymerisation in der Wasser- sowie in der Polymerphase berücksichtigt. Die Teilchenbildung soll durch homogene Nukleierung erfolgen. Es wird angenommen, daß die Konzentration des Monomeren in den Phasen durch ein Nernstsches Verteilungsgleichgewicht bestimmt wird. Zu Vergleichszwecken wurde auch die Polymerisation von MADAMBQ in Lösung und als nicht stabilisierte Fällungspolymerisation durchgeführt.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052450115
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  • 11
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    Electronic Resource
    An investigation of the grafting of cellulose powder with acrylamide under a magnetic field (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 246 (1997), S. 1-9 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Cellulosepulver, hergestellt durch Nitrierung von Eichen-Furfural-Lignocellulose, wurde mit Acrylamid radikalisch gepfropft. Die Pfropfreaktion wurde sowohl in Gegenwart eines äußeren Magnetfeldes (0,15-0,35 T) als auch ohne Magnetfeld durchgeführt. Der Einfluß von Monomerkonzentration, Initiatorkonzentration, Polymerisationszeit und temperatur sowie der magnetischen Feldstärke auf den Polymerisationsverlauf wurde untersucht. Es wurde festgestellt, daß der Pfropfumsatz mit zunehmender Feldstärke signifikant ansteigt.
    Notes: Cellulose powder obtained from oak furfural lignocellulose by nitration reaction was grafted with acrylamide using a radical initiation. The grafting reactions were carried out and compared both in presence and in absence of a continuous external magnetic field with the intensity extended between 0.15-0.35 T. The effect of monomer and initiator concentration, time and temperature of reaction and magnetic field intensity onto the grafting process were examined. It was observed that the presence of a magnetic field leads to a significant increase of the graft conversion.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052460101
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  • 12
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    Electronic Resource
    Radical polymerization of poly(butyl acrylate) in the presence of poly(L-lactic acid), 1. Synthesis, characterization and properties of blends (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 246 (1997), S. 49-63 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Poly(L-milchsäure) ist ein biokompatibler, semikristalliner, thermoplastischer Polyester mit ungünstigen mechanischen Eigenschaften. Daher wurde in einem “reactive blending”-Prozeß ein Acrylkautschuk, n-Butylacrylat, mittels einer Suspensionspolymerisation in Wasser auf in einem organischen Lösungsmittel gelöste Poly(L-milchsäure) gepfropft. Die gebildeten Copolymeren konnten isoliert und durch NMR-Spektroskopie und DSC-Messungen charakterisiert werden. Die Untersuchung der mechanischen Eigenschaften ergab keine befriedigenden Ergebnisse, weil die Kautschukphase wahrscheinlich aus viskosen linearen Makromolekülen besteht und daher keine elastischen Eigenschaften besitzt. In weiteren Arbeiten soll der Syntheseweg so modifiziert werden, daß durch den Einbau von Diacrylaten eine zumindest partielle Vernetzung der Kautschukphase erreicht wird.
    Notes: Poly(L-lactic acid) is a biocompatible polyester, semicrystalline, thermoplastic, with low versatility in mechanical properties. To overcome this problem, a reactive blending procedure was performed by grafting an acrylic rubber, n-butyl acrylate, via water suspension polymerization onto poly(L-lactic acid) dissolved in an organic solvent. It was possible to isolate the copolymeric phase formed from the two polymers and characterize it by using NMR and DSC techniques. Mechanical tests on blends gave no satisfactory response, probably because the rubbery phase is composed essentially of viscous linear macromolecules, not able to perform elastic properties. Work is in progress to modify the synthetic pathway to incorporate diacrylates in order to realize a rubbery phase at least partially cross-linked.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052460104
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  • 13
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    Tin-coupled styrene-butadiene rubbers (SBRs). Relationship between coupling type and propertiesBased on a paper presented at the 148th Meeting of the Rubber Division, American Chemical Society, Cleveland, Ohio, 17-20 October 1995. (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 246 (1997), S. 85-96 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Zur Entwicklung von neuen Styrol-Butadien-Kautschuken (SBRs) für Reifenanwendungen sind mehrere Arten von Zinn-Polymer-Bindungen (Styryl-, Butadienyl-, Isoprenyl- and α-Methylstyryl-Zinn) sowohl in linearen als auch in verzweigten Ketten untersucht worden. Die dynamisch-mechanischen Eigenschaften von Vulkanisaten mit Ruß wurden analysiert, um eine Beziehung zwischen den Strukturparametern der Polymeren und den Materialeigenschaften herzustellen. Der Polymer-Füll-stoff-Wechselwirkungsparameter, der durch das Verhältnis von mechanischen und dynamischen Termen definiert ist, wurde zur Charakterisierung der Verbindungen herangezogen. Der Einbau von verschiedenen Zinn-Polymer-Bindungen in lineare und in verzweigte SBR-Ketten bewirkte eine Verbesserung der Hystereseeigenschaf-ten der Vulkanisate und eine Veranderung des Wechselwirkungsparameters.
    Notes: Following the development of new SBRs for tyre applications, several kinds of tin-polymer bonds (styryl-, butadienyl-, isoprenyl- and α-methylstyryltin) have been studied, in both branched and linear chains.Dynamic-mechanical properties of the carbon black vulcanizates have been analyzed to establish a relationship between structural parameters of polymers and compound properties. The filler-polymer interaction parameter, defined by a ratio of mechanical and dynamic terms, has been used for the evaluation of the compounds. The introduction of different types of tin-polymer bonds, in branched and linear chains of the SBRs, implies an improvement in the hysteresis properties of the vulcanizates as well as a modification of the interaction parameter.
    Additional Material: 1 Ill.
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    A novel spin-finishing method for antistatic modification of polyester fiber. Surface reaction onto amine-containing copoly(amide-ethers) blended with polyester fiber (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 246 (1997), S. 109-123 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Copoly (amid-ether) rnit zwei unteschiedlichen Aminfunktionalitäten wurden als antistatische Modifikatoren für Polyethylenterephthalatfasern (PET) eingesetzt. Die tertiären Aminogruppen schmelzegesponnener Copolymerfilamente wurden rnit drei Alkylierungsmitteln umgesetzt, wobei ein Sulfobetain, ein Carbobetain bzw. Ammoniumionen gebildet wurden. Dadurch wurde der scheinbare spezifische Widerstand der Filamente auf größfienordnungsmäßfiig 106 bis 108 Ω/cm verringert. Da sich die quaternisierten Copolymeren beim Blend-Spinnen rnit PET zersetzen, wurden Blendfasern von PET mit einem Copolymeren nach dem Schmelzespinnen einer Quaternisierung oder Vernetzung rnit Alkylierungsmitteln bzw. Epoxyvernetzern unterzogen, was die antistatischen Eigenschaften der Fasern im Vergleich rnit der unbehandelten Faser verbesserte. Insbesondere die mit Epoxiden vernetzten Fasern wiesen antistatische Eigenschaften auf, wie sie mit dieser Modifizierungsmethode bislang nicht erreicht wurden. Die antistatischen Eigenschaften blieben nach dem Fkben erhalten, da sowohl die hydrophilen als auch die ionischen Gruppen auf der Faseroberflache immobilisiert waren. Da Quaternisierung bzw. Vernetzung in einem Arbeitsgang rnit dem Verspinnen und Verstrecken der Fasern innerhalb einer kurzen Reaktionszeit erfolgen, sollte diese “spin-finishing„ genannte Methode konventio- nellen Verfahren bezuglich Kosten und Produktivitat uberlegen sein.
    Notes: Copoly(amide-ethers) containing two types of tertiary amine units were made as antistatic modifiers for poly(ethylene terephthalate) (PET) fibers. The filaments of the copolymers were melt-spun and reacted with three alkylating agents in order to quaternize the tertiary amine into a sulfo-betaine, a carbobetaine, and an ammonium ion. The apparent electric resistivity of the filaments was greatly reduced by this reaction, being in the range of 106 to 108 Ω/cm. However, because these quaternized copolymers incurred decomposition during blend spinning with PET, a blend PET fiber containing one type of copoly(amide-ether) was melt-spun and subjected to quaternization of the amino groups as well as to surface crosslinking with various alkylating and epoxy agents. The quaternized blend fibers obtained showed improved antistatic properties compared with the original blend fiber. Particularly, the fibers crosslinked with epoxy compounds were found to have the best antistatic properties that had ever been attained with this type of modification. The antistatic properties were retained even after dyeing, because both hydrophilic and ionic groups had been effectively immobilized on the surface. Since this quaternization and crosslinking could be conducted on-line with spinning and drawing within a short reaction time, this modification technique is called “spin-finishing method”, which should be superior to the conventional methods in terms of cost performance and productivity.
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    Etching of a low-density polyethylene film by fuming nitric acid (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 249 (1997), S. 33-46 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Filme aus Polyethylen niedriger Dichte (LDPE) wurden mit rauchender Salpetersäure behandelt. Die Oberflächeneigenschaften sowie die Bildung polarer Gruppen wie auf der geätzten Filmoberfläche wurden mit SEM-, IR- und XPS-Methoden analysiert. Die mechanische Festigkeit eines aus dem geätzten LDPE-Film und einem Epoxidharz hergestellten Laminats sowie die Bedruckbarkeit der geätzten Oberflächen wurden untersucht und mit einer unbehandelten Probe verglichen. Die Oberflächenrauhigkeit und die Gegenwart polarer Gruppen erhöhen die mechanische Festigkeit des Laminats aus dem geätzten Film durch mechanische Verankerung und chemischer Wechselwirkungen. Die Oberfläche des behandelten LDPE-Films ist besser bedruckbar als die des unbehandelten Films.
    Notes: Low-density polyethylene (LDPE) films were treated with fuming nitric acid (FNA). The surface characteristics and also the insertion of polar groups like on the etched LDPE film surface were measured by SEM, IR and XPS analyses, respectively. The mechanical performance of a laminate of the etched film with epoxy resin and also the printability of the etched film surface were tested and compared with the unetched sample. The surface roughening and the presence of polar groups enhance the mechanical strength of the laminate of FNA-treated film due to mechanical interlocking and chemical interaction. The printability of the treated film surface is also superior to that of the untreated LDPE film surface.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052490103
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    Celluloseether als Trennschichten hydrophiler Polymermembranen (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 249 (1997), S. 11-32 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: This paper reports on polymer membranes characterized by a surface layer of hydroxyalkyl derivatives of cellulose. Water compatible polymers like hydroxyalkyl derivatives of cellulose are preferably those exhibiting good chemical stability and desired membrane characteristics. Normally, water-compatible polymers used in the coating solutions must be rendered water-insoluble after coating. By adapting crosslinking conditions on separation problems, the membranes are useful for many processes in the fields of biotechnology, food and chemical industry.The membranes presented here possess the advantage of being highly resistant to chemical and biological degradation and, hence, have long lifetimes under many process conditions.
    Notes: Es wird die Entwicklung hydrophiler Polymermembranen diskutiert, die nach Beschichtung mit Celluloseethern und anschließender Vernetzung auf den asymmetrischen Trägermembranen interessante Permeations- und Trenneigenschaften bei hervorragenden chemischen Stabilitäten, vor allem beim Membrantrennverfahren der Nanofiltration, aufzeigen. Weiterhin werden Aussagen zu den Gastrenneigenschaften der Celluloseetherkompositmembranen getroffen.Erläutert werden die Permeations- und Trenndaten der Kompositmembranen in Korrelation zur Vernetzung der Celluloseether anhand verschiedener Einflußgrößen, was qualitative und gegebenenfalls quantitative Aussagen zum Vernetzungsmechanismus der Celluloseetherderivate erlaubt. Dabei stehen die Vernetzungstemperatur, der Einfluß der katalysierenden Wasserstoffionen und bedingt die Vernetzungszeit im Vordergrund. Abgerundet werden die Arbeiten durch Ermittlungen rheologischer Daten, die in Zusammenhang zu den Vernetzungsreaktionen und damit zu membranspezifischen Größen stehen.Infolge der hervorragenden chemischen Stabilität der Celluloseether werden Einsatzmöglichkeiten der Kompositmembranen zur Nanofiltration niedermolekularer Verbindungen aus organisch hochbelasteten Systemen beschrieben.
    Additional Material: 30 Ill.
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    Products of polycondensation of 4,4′-biphenyldithiol with some hydrocarbon dihalides (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 13-21 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polysulfide wurden mit hoher Ausbeute durch Hochtemperatur-Lösungspolykondensation von 4,4′-Dimercaptobiphenyl mit ausgewählten aliphatischen und aromatisch-aliphatischen Dihalogenkohlenwasserstoffen hergestellt. Um die optimalen Polykondensationsbedingungen zu bestimmen, wurde der Einfluß folgender Faktoren auf die reduzierte Viskosität und die Ausbeute der Polysulfide ermittelt: Art des organischen Lösungsmittels, Art des Halogenwasserstoff-Akzeptors, Konzentration der organischen Reagenzien, Reaktionstemperatur und -zeit. Die Polykondensation des Dithiols mit Bis(4-chlormethylphenyl)methan wurde als Modellsystem eingehender untersucht. Die Polysulfidstrukturen wurden mittels Elementaranalyse, IR-Spektroskopie und Röntgenstrukturanalyse bestätigt. Aus der thermogravimetrischen Analyse wurden die Zersetzungstemperatur, der Gewichtsverlust bei dieser Temperatur und das Maximum der Zersetzungsgeschwindigkeit erhalten. Weiterhin wurden einige physikalisch-chemische, mechanische und dielektrische Eigenschaften ermittelt. Die beste thermische und chemische Bestandigkeit zeigt das aus dem Dithiol und 4,4′-Bis(chlormethyl)biphenyl hergestellte Polysulfid, was auf dessen vorwiegend aromatische Struktur zuriickgefuhrt werden kann.
    Notes: Polysulfides were synthesized with high yield by high-temperature solution polycondensation of 4,4′-biphenyldithiol with selected aliphatic and aromatic-aliphatic hydrocarbon dihalides. To determine the optimum polycondensation conditions, the influence of the following factors on reduced viscosity and yield was studied: type of organic solvent, type of hydrogen halide acceptor, concentration of reagents, reaction temperature, and reaction time. A thorough examination was carried out only for the polycondensation of dithiol with bis(4-chloromethylphenyl)methane chosen as model system. The structures of the polysulfides were confirmed by elemental analysis, X-ray analysis, and infrared spectroscopy. The temperature of initial decomposition, the percentage of mass loss, and the temperature of the fastest decomposition, process were determined from curves of differential thermal and thermogravimetric analysis. Some physicochemical, mechanical and electrical properties were determined. The highest thermal and chemical resistance has been found for the polysulfide obtained from 4,4′-biphenyldithiol and 4,4′-bis(chloromethyl)biphenyl, probably because of the predominantly aromatic structure.
    Additional Material: 4 Ill.
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    Organic-inorganic hybrid sol-gel materials, 2. Application for dental composites (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 61-72 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Drie organisch-anorganische Hybridmaterialien wurden nach dem Sol-Gel-Verfahren durch kovalenten Einbau von Poly(styrol-co-methylmethacrylat)(Poly(St-co-MMA))-, Polymethylmethacrylat(PMMA)- und Polystyrol(PS)-Struktureinheiten in ein SiO2-Netzwerk hergestellt und als Füllstoffe (bis zu 60 Gew.-%) in Dentalharzen verwendet. Der Einfluß der Füllstoffe auf einige mechanische Eigenschaften der Harze wurde untersucht. Die Härte der gefüllten Dentalharze nahm mit steigendem Füllstoffgehalt zu, wogegen die Biegefestigkeit abnahm. Die Druckfestigkeit der gefüllten Harze war besser als die des ungefüllten Harzes, nahm jedoch mit steigendem Füllstoffgehalt ab.
    Notes: By incorporating poly(methyl methacrylate) (PMMA), polystyrene (PS), and poly(styrene-co-methyl methacrylate) (poly(St-co-MMA)) structure units covalently into the SiO2 glass network via a sol-gel approach, three organic-inorganic hybrid materials (PMMA-SiO2, PS - SiO2, and poly(St-co-MMA) - SiO2) have been prepared. The three hybrid sol-gel materials were used as filler (up to 60 wt.-%) for dental composite resins. The effect of the three filler materials on several mechanical properties of the dental composite resins was investigated. The hardness of the filled dental composites increased with increasing filler content, whereas the bending strength decreased. The compressive strength of the composites was improved, compared with the unfilled resin, but decreased with inreasing filler content.
    Additional Material: 6 Ill.
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    Adsorption of BTX compounds from aqueous solutions by water-insoluble starch (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 107-116 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Adsorption von Benzol, Toluol und p-Xylol (BTX) aus wäßrigen Lösungen mittels hochvernetzter kationischer Stärke mit tertiären Amingruppen wurde untersucht. Der endotherme Adsorptionsvorgang ist vom Anfangs-pH-Wert und der Anfangskonzentration abhängig und kann mit einer Langmuir-Isotherme beschrieben werden.Die Adsorptionswärme (Δ) bei pH 4 beträgt für Benzol, Toluol und Xylol 29,45 kJ mol-1, 34,41 kJ mol-1 bzw. 35,58 kJ mol-1, bei pH 10 30,17 kJ mol-1, 35.56 kJ mol-1 bzw. 39,39 kJ mol-1. Die adsorbierte Menge nimmt in der Reihenfolge Benzol 〉 Toluol 〉 Xylol ab.
    Notes: The removal of benzene, toluene and p-xylene (BTX) compounds from aqueous solutions with highly crosslinked cationic starch containing tertiary amine groups was investigated. The adsorption process has found to be initial pH- and initial concentration-dependent, endothermic, and follows the Langmuir isothermal adsorption.The heats of adsorption (ΔH) at initial pH = 4 of benzene, toluene and p-xylene compounds are 29.45 kJ mol-1, 34.41 kJ mol-1, and 35.58 kJ mol-1, respectively, those at initial pH = 10 are 30.17 kJ mol-1, 35.56 kJ mol-1, and 39.39 kJ mol-1, respectively. The order of the amount of adsorbed BTX compounds on the adsorbent is benzene 〉 toluene 〉 p-xylene.
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    Thermogravimetric and ESR studies of polymer/metal precursors for high-temperature superconductors (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 157-170 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Bi-Sr-Ca-Cu-Komplexverbindungen von Polymethacrylsäure (PMAA) und Kresolnovolaken, die als Precursoren für Hochtemperatursupraleiter (HTSL) eingesetzt werden, sowie deren Cu-Komplexsalze wurden ESR-spektroskopisch und thermogravimetrisch untersucht. In den PMAA-Proben wurden drei verschiedene Cu2+-Spezies nachgewiesen: i) Cu2+-Paare, ii) isolierte Cu2+-Ionen und iii) Cu2+-Cluster. Bei niedrigem Cu-Gehalt der Proben bilden die Cu2+-Paar-Bindungen den Hauptanteil, bei hohem Cu-Gehalt überwiegen die Clusterbindungen. In den Novolakproben wurden nur isolierte Cu2+-Ionen und Cu2+-Cluster nachgewiesen. Die Einführung der Cu-Ionen erniedrigt die thermische Stabilität der Polymeren, der thermische Abbau erfolgt stufenweise. In den PMAA-Proben wird die erste Abbaustufe bei ≈ 220°C durch die Cu2+-Paar-Komplexe verursacht.
    Notes: Bi-Sr-Ca-Cu complexes of poly(methacrylic acid) (PMAA) and cresol novolac, which are precursors for high-temperature superconductors (HTSC) and Cu complexes of those polymers were investigated by ESR spectroscopy and thermogravimetry. In the PMAA samples three different kinds of Cu2+ species were detected: i) Cu2+ pairs, ii) isolated Cu2+ ions and iii) Cu2+ clusters. While Cu2+ pairs are the main species at low Cu concentrations, clusters become dominant at high Cu contents. In the novolac samples Cu2+ was only detected in isolated sites and clusters. The introduction of Cu ions lowered the thermal stability of the polymers and led to a stepwise decomposition. In the PMAA samples the first decomposition step at ≈ 220°C is caused by the Cu2+ pair complexes.
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    Polymerization of 1,3-butadiene with neodymium chloride/2-ethylhexanolate/triethylaluminium catalyst systemIPCL communication No. 325. (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 193-205 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Neodymchlorid-2-ethylhexanolate mit der allgemeinen Formel NdCl3 · nL wurden durch eine Liganden-Austauschreaktion zwischen Neodymchloridisopropanolat (I) und 2-Ethylhexanol (EH) hergestellt. Die Hexanolate NdCl3 · 1,5 EH (II) und NdCl3 · 2,5 EH (III) wurden durch Elementaranalyse und Gravimetrie charakterisiert. Die katalytische Aktivität der Hexanolate bei der Homopolymerisation von 1,3-Butadien in Gegenwart von Triethylaluminium wurde untersucht. Die Verbindung III zeigte eine höhere Aktivität als die Verbindung II. Höhere Katalysator- und Cokatalysatorkonzentrationen sowie eine höhere Temperatur steigerten den Umsatz, wogegen die Viskosität der Produkte abnahm. Mit zunehmender Reaktionszeit erhöhten sich sowohl der Umsatz als auch die Viskosität. Die cis-1,4-Konformation wurde durch die Variation von Temperatur und Cokatalysatorkonzentration beeinflußt. Der gesamte Anteil der cis-1,4-Stuktur lag jedoch in allen Fällen über 99%, während die Produkte nur einen sehr geringen Vinyl-Anteil von 〈1% enthielten. Die Zugabe einer elektronenspendenden Verbindung verringerte den cis- 1,4-Gehalt aber auf 87%.
    Notes: Neodymium chloride 2-ethylhexanolates of the general formula NdCl3 · nL were prepared by ligand exchange reaction between neodymium chloride ispropanolate (I) and 2-ethylhexanol (EH). These hexanolates, NdCl3 · 1.5 EH (II) and NdCl3 · 2.5 EH (III), were characterized by elemental analysis and gravimetry. The catalytic activity of these hexanolates in combination with triethyl aluminium in the homopolymerization of 1,3-butadiene was studied, and the activity was found to be higher with III than II. The conversions increased with increasing the catalyst and co-catalyst concentrations and the temperature, whereas the intrinsic viscosity decreased. The conversions and the intrinsic viscosity decreased. The conversions and the intrinsic viscosity increased with reaction time. The cis-1,4 structure was influenced by variation in temperature and co-catalyst concentration, however, the total cis-1,4 structure was always more than 99% with very low vinyl content (〉1%). Addition of an external electron donor decreased the cis-1,4 content to 87%.
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    The effects of desolvation methods of the recrystallized MgCl2-alcohol adduct on catalyst characteristics and the bulk density of polyethylene (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 253 (1997), S. 17-25 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: MgCl2-Träger für einen Ethylenpolymerisationskatalysator wurden mit Hilfe der Rekristallationsmethode hergestellt, wobei Methanol als Lösungsmittel diente. Der Einfluß verschiedener Lösungsmethoden des rekristallisierten MgCl2-Alkohol-Adduktes auf die morphologischen Charakteristika der Katalysatoren wurde untersucht. Die Lösungsmethode beeinflußt die Eigenschaften der Katalysatoren beträchtlich. Die dargestellten Katalysatoren wiesen unterschiedliche Ti/Mg-Verhältnisse auf, sowohl was die Oberfläche als auch die gesamten Katalysator-Partikel betrifft. Betrachtet man die Ti-Verteilung und Aktivitätsprofile, dann erweisen sich nicht nur die Polymerisationsbedingungen, sondern auch die Ti-Verteilung auf dem Katalysator als wichtige Faktoren, welche die Dichte der Polymeren beeinflussen.
    Notes: The MgCl2 supports for an ethylene polymerization catalyst were prepared by the recrystallization method using methanol as a solvent. The effects of different desolvation methods of the recrystallized MgCl2-alcohol adduct on the morphological characteristics of the catalysts were examined. The desolvation method greatly affects the characteristics of the catalyst. The prepared catalysts had different Ti/Mg ratios with respect to both surface content and entire catalyst particles. Considering Ti distribution and activity profiles, not only the polymerization conditions but also the Ti distribution on the catalyst appear to be an important factor which affects the bulk density of the polymers.
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    Synthesis of aromatic poly(ether ketone)s with ferrocene units in the main chain (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 253 (1997), S. 89-97 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aromatische Poly(etherketon)e mit Ferrocen-Einheiten in der Hauptkette wurden durch direkte Polykondensation von 1,1′-Ferrocendicarbonsäure mit Diphenylether oder 1,4-Diphenoxybenzol hergestellt. Als Katalysatoren wurden Trifluormethansulfonsäure, Methansulfonsäure/P2O5 (Eatons Reagens) oder Trifluormethansulfonsäure/P2O5 verwendet. Polykondensationen bei Raumtemperatur für 24 h ergaben Poly(arylenetherketon)e mit Grenzviskositäten bis zu 40 mL g-1. Die Monoacylierung von Diphenylether mit Ferrocencarbonsäure wurde im Hinblick auf die Effektivität von Eatons Reagens als Katalysator und Lösungsmittel eingehender untersucht.
    Notes: Aromatic poly(ether ketone)s with ferrocene units in the main chain were prepared by direct polycondensation of 1,1′-ferrocenedicarboxylic acid with diphenyl ether or 1,4-diphenoxybenzene using various catalysts such as trifluoromethanesulfonic acid (triflic acid), a combination of methanesulfonic acid/P2O5 (Eaton's reagent) or a combination of triflic acid/P2O5. Polycondensations at room temperature for 24 h gave poly(arylene ether ketone)s with inherent viscosities up to 40 mL g-1. Monoacylation of diphenyl ether with ferrocenecarboxylic acid was studied in detail in order to show the efficiency of polymer formation employing Eaton's reagent as catalyst and solvent.
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    Mechanical and structural characteristics of phenolphthalein poly(ether sulfone)/ultra-high molecular weight polyethylene blends (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 73-80 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die mechanischen und strukturellen Eigenschaften von Blends aus Phenolphthalein-Polyethersulfon und ultrahochmolekularem Polyethylen (UHMWPE) wurden anhand von Zug- und Biegeversuchen, Raster- und Transmissionselektronenmikroskopie untersucht. Die Zugabe einer geringen Menge UHMWPE (2 Gew.-%) führt zu einer Verstärkung der PES-C-Matrix. Höhere UHMWPE-Konzentrationen verschlechtern die mechanischen Eigenschaften. Die Strukturuntersuchungen zeigen, daß die Blends im gesamten Zusammensetzungsbereich mehrphasig sind. Bei geringen UHMWPE-Konzentrationen ist die UHMWPE-Phase gleichmäßig verteilt und entlang der Fließrichtung orientiert, was mit der starken Grenzflächenadhäsion zur Verbesserung des mechanischen Verhaltens beiträgt. Mit steigender UHMWPE-Konzentration nimmt die Domänengröß der UHMWPE-Phase zu.
    Notes: Mechanical and structural properties of blends of phenolphthalein poly(ether sulfone) (PES-C) with ultra-high molecular weight polyethylene (UHMWPE) were investigated using tensile and bending testing, scanning electron microscopy and transition electron microscopy. The incorporation of minor amounts of UHMWPE (2 wt.-%) into PES-C has a reinforcement effect. With higher concentrations of UHMWPE, the mechanical properties decrease gradually. Structural studies demonstrated that the blends are multiphasic in the whole composition range. The minor UHMWPE, dispersed uniformly and oriented along the flow direction, as well as the strong interfacial adhesion contribute to the increase of the mechanical performance of the blends. The domain size of the UHMWPE phase was found to increase with the increase of its concentration.
    Additional Material: 6 Ill.
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    Redox copolymer with N-bromosulfonamide groups for the decomposition of cyanide ions in dilute aqueous solutions (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 117-130 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein Redoxcopolymeres, ein makroporöses Poly(Styrol-co-Divinylbenzol) (S/DVB)-Harz mit N-Bromsulfonamidgruppen, wurde angewandt, um Cyanide aus wäßrigen Lösungen zu entfernen. Dieses Harz enthält aktives Brom in den funktionellen Gruppen (1.86 mmol g-1, 3.72 meq g-1) und weist Oxidationseigenschaften auf. Es wurde sowohl in statischen als auch in dynamischen Systemen für die Oxidation von Cyanidionen zu nichttoxischen Verbindungen angewandt. Die Reaktionen wurden in wäßrigen Lösungen mit 26-2600 mg L-1 CN- bei unterschiedlichen pH-Werten durchgeführt. Die Ergebnisse zeigten, daß dieses Harz die Cyanide leicht zu Cyanaten oxidiert, die ca. 1000 mal weniger toxisch sind. Bei Kontakt mit dem Harz fiel die Cyanidkonzentration in den Lösungen unter 0.05 mg L-1 CN-. Die —SO2NBrNa-Gruppen gingen dabei in —SO2NH2-Gruppen über. Diese konnten wiederum mit Natriumhypochlorit- und Natriumbromid-Lösungen reaktiviert werden. Es wurde auch eine Alternative zu der Cyanidionenoxidation mit N-Bromsulfonamid-Harz untersucht, indem ein analoges N-Chlorsulfonamid-Harz in Gengenwart von katalytischen Mengen von Bromiden angewandt wurde.
    Notes: A redox copolymer, macroporous poly(styrene-co-divinylbenzene) (S/DVB) resin having N-bromosulfonamide groups, was used for removal of cyanide ions from aqueous solutions. This resin contains active bromine in functional groups (1.86 mmol g-1, i. e. 3.72 meq g-1) and shows oxidative properties. It was employed in static and flow system for oxidation of cyanide ions to non-toxic compounds. The reactions were carried out in aqueous media containing 26-2600 mg L-1 CN- at different pH values. The data showed that the resin having active bromine easily oxidized cyanides, forming cyanates being 1000-times less toxic than cyanides. In contact with the resin the concentration of cyanides in tested solutions dropped below 0.05 mg L-1 CN-. During the oxidation processes the —SO2NBrNa groups transform to —SO2NH2 groups. They can be reactivated by use of sodium hypochlorite and bromide solutions. As an alternative to oxidation of cyanides by N-bromosulfonamide resin, the oxidation of these ions by N-chlorosulfonamide resin with addition of a small amount of bromides was examined.
    Additional Material: 3 Ill.
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    Mitteilungen/Announcements (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 207-208 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: No Abstract
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052510118
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    Hydrolytic and thermal stability of novel polyurethane elastomers (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 252 (1997), S. 33-43 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Novel Polyester glycols with alkyl side groups were used for the improvement of thermal stability and hydrolytic stability of polyester urethane elastomers. The novel polyester glycols used are poly( β -methyl- δ -valerolactone)glycol (PMVL), poly(3-methyl pentamethylene adipate) glycol (PMPA), poly(nonamethylene-co-2-methyl octamcthylene carbonate) gycol (PNCO). A mixture of PNCO and poly(dimethyl siloxane)gycol (PNCO/PDMS) was also used. Polyurethane network elastomers were prepared from 4,4′-diphenylmethane diisocyanate (or 2,4-tolylene diisocyanate), and a mixture of 1,4-butane diol and trimethylol propane by a prepolymer method. Mechanical properties, Tg, thermal stability, and hydrolytic stability were measured. Morphology were also measured by means of polarizing microscopy, dynamic viscoelastometer, and ESR. The properties of novel polyurethane elastomers have good mechanical properties comparable to those of the general purpose polyester urethanes, and better thermal and hydrolytic stability than PTMG-based polyurethane. These polyurethane elastomers were exposed in out door during 2 year in Nagasaki, JAPAN. The novel polyurethane clastomers held alomost constant values for gel fraction, swelling ratio, relative modulus during 12 months, while poly(oxytetramethylene oxide)-based polyurethane as a control decreased the these values. Relationship of degradation behaviors with chemical structure and morphology were discussed.
    Additional Material: 9 Ill.
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    Oxidizability of lactams and lactam-based polyamidesDedicated to Dr Jan Šebenda on the occasion of his 70th birthday (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 252 (1997), S. 139-151 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the chain oxidation of N-alkylamides with molecular oxygen, propagation is the ratedetermining step under conditions when the oxidation rate is independent of oxygen pressure. The oxidizability of lactams and lactam-based polyamides correlates with the energy of the formation of N-alkylamide radical by abstraction of hydrogen from the methylene group adjacent to nitrogen. While for lactams this energy depends on the number of carbons in the lactam ring, for N-alkylamides and polylactams such dependence is not observed.
    Additional Material: 1 Tab.
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    Use of EPR to image nitroxyl radicals in hals stabilized polymers (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 252 (1997), S. 179-193 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An X-band EPR-Imaging apparatus which allowed us to determine the distribution of nitroxyl radicals within solid samples of polymeric materials containing hindered amine stabilizers, is described. It is shown that EPR Imaging represents a powerful tool for investigating the growth and decay of nitroxyls formed in polymers irradiated under air for long periods. Since the variations of the radical concentration can be monitored both in time and in the space, this technique provides valuable information not easily attainable by means of other methods.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052520113
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    Photo-oxidation mechanisms of poly(2,6-dimethyl-1,4-phenylene oxide). (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 252 (1997), S. 237-256 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A re-examination of the photo-oxidation mechanism of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) at both long and short irradiation wavelengths under accelerated conditions is reported. The formation rate of poly-2,6-dimethylphenoxy (PDMP) radicals, have been observed by esr spectroscopy, while benzylic-type radicals have been detected by spin trapping experiments using nitrosodurene under UV irradiation conditions. The changes of FTIR spectra obtained under accelerated photo-oxidative conditions show the formation of primary oxidation products such as aromatic aldehydes and quinones. The direct formation of radical cations and superoxide anions by a photo-induced electron-transfer reaction is suggested under our conditions. In addition, some results on the of photo-oxidation PPO/PS blends as a function of polystyrene tacticity are also reported. In the case of syndiotactic polystyrene the blend photostability shows some differences in comparison with the blend containing atactic polystyrene. This effect has been ascribed to the absence of excimers in syndiotactic polystyrene which are not revealed by fluorescence measurements. Finally, the chemical modification of PPO with bromine gave a bromomethylated PPO with different amounts of CH2 Br groups, which has been used for further substitution reactions with alkoxy sodium salts of 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and 4-hydroxy-1,2,2,6,6-pentamethylpiperidine (PMPP). The accelerated photo-oxidation of a modified copolymer PPO-PMPP containing a 60% PMPP moieties as side groups and its blends with pure PPO has been followed by FTIR and esr spectroscopies. Some comparisons with a commercially available hindered amine light stabilizers (HALS) and a modified copolymer PPO-PMPP are also reported under the same photo-oxidative conditions.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052520116
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    Zähigkeit und Relaxationsverhalten von Polymethylmethacrylat, Polystyrol und Polycarbonat (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 253 (1997), S. 27-49 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: For innovative applications of plastics, which take advantage of special properties of polymeric materials, comprehensive understanding on strengthening and toughening mechanisms is required. The temperature-dependent mechanical behaviour of PMMA, PS and PC under dynamic loading conditions were investigated by means of an instrumented Charpy impact tester. The elastic-plastic fracture mechanics parameters, the energy-determined J-integral, and the deformation-determined crack opening displacement, δ, enable to do structure-related quantification of micromechanical processes. The J-integral values showed a maximum, resulting from an energy-dissipative process. The maximum values for PMMA occurred at 50°C and for PC at 40°C , which is related to the secondary(β) relaxation as evaluated from the frequency dependence of the mechanical loss factor. The 0-relaxation initiated shear deformation mechanisms, which led to a local increase of toughness. In polycarbonate, toughness is strongly increased due to a stress-induced shear flow process at temperatures higher than -25°C. Correlations between morphology and toughness can be derived with the help of optical investigations of stable crack propagation on fracture surfaces.
    Notes: Innovative Kunststoffanwendungen, die die speziellen Eigenschaften polymerer Werkstoffe gezielt ausnutzen, erfordern vertiefte Kenntnisse über festigkeits- und zähigkeitsbestimmende Mechanismen. Das sich in Abhängigkeit von der Temperatur ändernde Werkstoffverhalten von PMMA, PS und PC wurde bei dynamischer Beanspruchung mittels instrumentierter Kerbschlagbiegeprüfung bestimmt. Mit der verformungsbestimmten Rißöffnungsverschiebung δ und dem energiebestimmten J-Integral stehen Kenngrößen der Fließbruchmechanik zur Verfügung, die eine strukturbezogene Quantifizierung der temperaturabhängigen mikromechanischen Prozesse erlauben. Die J-Integralwerte zeigen für PMMA bei 50°C und für PC bei -60°C ein durch einen energiedissipativen Prozeß verursachtes Maximum. Dieses Maximum steht, wie sich aus der Interpretation der Frequenzabhängigkeit des mechanischen Verlustfaktors ergibt, mit der Neben(β)-Relaxation in Beziehung. Dabei initiiert die β-Relaxation Scherdeformationsmechanismen, die ihrerseits die lokale Zähigkeitserhöhung bewirken. Ab -25°C führt für PC ein spannungsinduzierter Scherfließprozeß zu einer erheblichen Zähigkeitssteigerung. Durch die Einbeziehung lichtmikroskopischer Untersuchungen des stabilen Rißfortschritts auf der Bruchfläche können Morphologie-Zähigkeits-Korrelationen abgeleitet werden.
    Additional Material: 16 Ill.
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    Thermostable block copolymers, 2Part 1 cf. 16.. Preparation and characterization of soluble blockcopolyimides (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 253 (1997), S. 71-88 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Eine Reihe von Polyamidimid-Polyimid-Blockcopolymeren (PAI-PI-BCPs) wurde durch Polykondensation von PAI-Blöcken mit Amino-Endgruppen und PI-Blöcken mit Anhydrid-Endgruppen hergestellt. Zur Synthese der Blöcke mit Molekulargewichten im Bereich von ca. 2000 bis 15000 wurden nur technisch leicht zugängliche Monomere, wie Trimellitsäureanhydridchlorid, Benzophenontetracarbonsäuredianhydrid, 4,4′-Diaminodiphenylmethan, 2,4-Toluylendiamin und 4,4′-Diaminodiphenylsulfon eingesetzt. Dabei zeigte sich, daß durch den blockartigen Aufbau die Löslichkeit-und damit die Verarbeitbarkeit-im Vergleich zu den reinen, unlöslichen Polyimiden wesentlich verbessert werden konnte, bei nahezu gleichbleibender Thermostabilität. So wurden BCPs mit guten mechanischen Eigenschaften, Thermostabilitäten bis ca. 480°C (Thermogravimetrie, 5% Gewichtsverlust) und guten Löslichkeiten in Dimethylacetamid und anderen polaren aprotischen Lösungsmitteln erhalten.
    Notes: New poly(amide-imide)-poly(imide) block copolymers (PAI-PI-BCPs) were prepared by polycondensation of amino-terminated PAI-blocks with anhydride-terminated PI-blocks. For the syntheses of the blocks with molecular weights from 2000 to 15000 only commercially available monomers were used, e.g. trimellitic acid anhydride chloride, benzophenone tetracarboxylic acid dianhydride, 4,4′-diaminodiphenylmethane, 2,4-toluenediamine and 4,4′-diaminodiphenylsulfone. The BCPs were shown to have better solubility compared to the pure, insoluble PIs with only minor decrease of the thermostability. Thus, BCPs with good mechanical properties, thermostabilities up to 480°C (thermogravimetric analysis, 5% weight loss) and good solubility in dimethylacetamide and other polar aprotic solvents were obtained.
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    Block and graft copolymers with polysiloxane and poly(N-acyliminoethylene) sequences (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 253 (1997), S. 139-149 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Eine Reihe von Polysiloxan/Poly(N-acetyliminoethylen)-(PSiO/PNAI)-Block- und -Pfropfcopolymeren wurde durch Polymerisation von 2-Methyl-2-oxazolin (MeOZO) mit funktionellen Polysiloxan-Prepolymeren als Initiatoren synthetisiert. Die Copolymeren wurden mit IR- und 1H NMR-Spektroskopie sowie Elementaranalyse, Differentialkalorimetrie und Thermogravimetrie charakterisiert. Der Einbau sowohl von hydrophoben als auch von hydrophilen Sequenzen verleiht den Polymeren amphiphile Eigenschaften. Ihre Eigenschaften in Lösung und als Feststoffe lassen die Produkte für Anwendungen als nichtionische Emulgatoren, Oberflächenmodifikatoren, Gele, usw. geeignet erscheinen.
    Notes: A series of polysiloxane/poly(N-acetyliminoethylene) (PSiO/PNAI) block and graft copolymers were synthesized by the initiation of 2-methyl-2-oxazoline (Me-OZO) polymerization with functional polysiloxane prepolymers. The copolymerization products were characterized by IR- and 1H NMR spectroscopy, elemental analysis, DSC and thermogravimetry. The insertion of both hydrophobic and hydrophilic sequences in the macromolecular structure induces a behavior characteristic of amphiphilic compounds. Their solution and solid state behavior evidenced peculiarities which make them able to act as nonionic emulsifiers, surface modifiers, gels, etc.
    Additional Material: 4 Ill.
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    The state of water in styrene-grafted and sulfonated poly(vinylidene fluoride) membranes (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 253 (1997), S. 151-167 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Zustand von Wasser in Protonenaustausch-Membranen, hergestellt durch Pfropfen von Styrol auf Polyvinylidenfluorid-Filme (PVDF-g-PS) mittels Elektronenstrahlen und anschließendes Sulfonieren (PVDF-g-PSSA), wurde mittels Differentialkalorimetrie (DSC), Raman-Spektroskopie und Rontgen-Diffraktion (SAXS) ermittelt. Die Raman-Untersuchungen zeigten, daß einzelne Wassermolekule durch hydrophobe Wechselwirkungen an die Polymerketten gebunden sind. Die DSC-Untersuchungen zeigten, daß Wasser in den Membranen in drei verschiedenen Umgebungen vorliegt: nicht gefrierendes ionisch gebundenes Wasser, gefrierendes freies Wasser und gefrierendes gebundenes Wasser. Die Menge an nicht gefrierendem Wasser betragt unabhangig vom Pfropfungsgrad etwa 10 H2O/SO3H (mol/mol). Die Menge an gefrierendem Wasser ist stark vom Pfropfungsgrad abhangig. Oberhalb eines Pfropfungsgrades von 50% werden Werte von 40 H20/S03H (mol/mol) erreicht. Die Leitfahigkeit von nur nicht gefrierendes Wasser enthaltenden Membranen ist gering, d. h., das ionisch gebundene Wasser kann nicht allein die fur den Transport von Protonen und Wasser notwendigen Kanale bilden. Die SAXS Untersuchungen zeigten, daß Wasser/Sulfonsaure-Cluster in Membranen aus hydratisiertem PVDF-g-PSSA mit einem Bragg-Abstand von 25 Å gebildet werden. Diese Cluster formen die Kanale fur den Ionentransport und die Leitfähigkeit.
    Notes: The state of water in proton exchange membranes prepared by pre-irradiation (electron beam, 100 kGy) grafting of styrene onto poly(vinylidene fluoride) films (PVDF-g-PS), followed by sulfonation (PVDF-g-PSSA), has been studied with thermal analysis, Raman spectroscopy and small angle X-ray diffraction (SAXS). Raman spectra show that, in addition to free liquid water in the membranes, single water molecules are weakly bound to the polymer backbone. Thermal analysis shows that there are three types of water molecules in the membrane; non-freezable water associated with the ionic sites, freezable free water, and freezable bound water. The amount of non-freezable water is around 10 H2O/SO3H (mol/mol), and is independent of the degree of grafting (d.o.g.). The amount of freezable water is strongly dependent on the d.o.g. as long as the grafting has not penetrated the whole of the film, and reaches a value of around 40 H2O/SO3H (mol/mol) above a d.o.g. of 50%. The conductivity of membranes containing only the non-freezable water is low, i. e. the ionically bound water alone does not form the domains necessary for proton and water transport. SAXS measurements show that water/sulfonic acid clusters in hydrated PVDF-g-PSSA membranes with a Bragg distance of 25 Å are formed; these form the ion conducting channels in the membrane.
    Additional Material: 9 Ill.
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    MITTEILUNGEN/ANNOUNCEMENTS (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 253 (1997), S. 211-211 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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    Tensile and flexural behavior of polypropene sheets with different crystallinities of surface layer (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 253 (1997), S. 201-210 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Zug- und Biegemoduli von preßgeformten Polypropen-Probekörpern mit unterschiedlichen Oberflächenkristallinitäten wurden basierend auf der Annahme eines Schicht-Verbund-Modells untersucht. Es zeigte sich, daß die Spannungs-Dehnungs-Kurven der Zugversuche und die Werte der Biegeablenkung im wesentlichen von der Oberfächenkristallinität abhängen, jedoch erwiesen sich die Bruchspannungen als von der Oberflächenkristallinität unabhängig. Es wird angenommen, daß das beobachtete Zug- und Biegeverhalten der Proben auf der Grundlage eines Schicht-Verbund-Modells, bei dem eine massive, starre Platte zwischen zwei weichen Schichten eingebettet ist, charakterisiert werden kann.
    Notes: The tensile and flexural moduli of the compression-molded sheets of polypropene with different surface layer crystallinity were investigated based on a layered composite model. It was found that the tensile stress-strain curve and flexural deflection depended largely on the surface layer crystallinity, but the ultimate strain-at-break values were independent of the surface layer crystallinity. It is suggested that the tensile and flexural behavior can be characterized using a layered composite model in which a bulk plate was sandwiched between two surface layers.
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    The role of charge transfer complexes in the photodegradation of polyolefins (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 252 (1997), S. 45-54 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Addition of HALS-stabilisers, the cut-off wavelength of the light source, the temperature and the oxygen pressure have an influence on the UV-degradation mechanism of polyolefins. All these parameters influences the conversion of oxygen into polymeric carbonyls. The results are explained assuming that the initiation of the UV-degradation of pololefins is due to substrate-oxygen charge transfer complexes (CTCs).
    Additional Material: 10 Ill.
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    Fracture behavior of exposed HDPE specimens with an embrittled layer due to UV-exposure (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 252 (1997), S. 69-88 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The applicability of fracture mechanics was studied on UV-exposed HDPE Charpy specimens. The failure distribution of the stress at failure measured in three-points bending tests showed a bifurcation in failure processes. At high stresses yielding occurs, resulting in large strain at failures. At lower stresses crack propagation causes low strain at failures. Due to the bifurcation in failure processes the ductile-brittle transition temperature of exposed specimens is hard to determine.Specimens notched after exposure showed a decrease in the critical stress intensity values. The effective notch depth of exposed specimens was found to be larger than the thickness of the oxidized layer measured by FT-IR and density measurements.
    Additional Material: 21 Ill.
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    Deactivation processes of 2-hydroxyphenyl-1,3,5-triazines  -  polymeric and monomeric UV absorbers of the benzotriazole and triazine class (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 252 (1997), S. 119-138 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the 2-hydroxyphenyl-1,3,5-triazines, the intramolecular hydrogen bond is stronger than in the corresponding 2-hydroxyphenylbenzotriazoles. Compounds with only one aryl group in the 2-hydroxyphenyl-1,3,5-triazine series show proton-transferred fluorescence with large Stokes shift and high quantum yield. No such fluorescence is observed, in contrast, for compunds with three aryi groups bearing no electrondonating groups on the aryl moieties. When the hydrogen atom of the intramolecular hydrogen bond is replaced by CH3, the respective derivative shows fluorescence with a normal Stokes shift.Various copolymers of MA-TIN 1 (2-[2-hydroxy-3-tert.-butyl-5-(O-[2-hydroxy-3-(2-methylpropenoyloxy)propyl]-2-carbonyloxyethyl)phenyl]benzotriazole), and MA-TZ 1 (2,4-Bis(2,4-dimethyl-phenyl)-6-[2-hydroxy-4-(2-hydroxy-3-[2-methylpropenoyloxy])propoxyphenyl]-1,3,5-triazine) with styrene, methyl methacrylate, and methacrylic acid have been synthesized by radical polymerization. The absorption spectra in the longwavelength UV region appear unchanged compared to those of the monomeric UV absorbers indicating that the stabilizer chromophores are conserved intact in the polymer. Both the monomeric and the polymeric stabilizers exhibit a strongly Stokesshifted, temperature-dependent, low-quantum-yield, proton-transferred fluorescence. This may be taken as evidence that the intramolecular hydrogen bond, which is essential for the photostability of this type of UV absorber, remains intact also in the copolymers. Activation energies of the radiationless deactivation process can be evaluated from the temperature dependence of this fluorescence. These energies lie between 4 and 5 kJ/mol for most of the benzotriazole and triazine stabilizers investigated.Fluorescence-decay measurements with crystalline MA-TIN 1 at different temperatures reveal a close correspondence of the temperature dependence between decay times and relative quantum yields. The radiationless process is thence concluded to originate from the proton-transferred level S1'. The decay time at room temperature is estimated at 70 ps, close to the value for crystalline TIN P (2-(2-hydroxy-5-methylphenyl)benzotriazole). The proton-transferred fluorescence of MA-TIN 1 exhibits a biexponential decay profile whereas solid TIN P, in contrast, displays only one single lifetime.
    Additional Material: 9 Ill.
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    Chemical stability of some poly(amide imide) type polymers (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 245 (1997), S. 105-112 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Saure- und Alkalibestandigkeit einiger heterozyklischer Poly(amidimid)e wurde mit der von strukturahnlichen Polyimiden und Poly(amidimid)en ohne heterozyklische Gruppen verglichen. Alle untersuchten Polymeren erwiesen sich in saurem Medium als sehr stabil. Der Einbau zusatzlicher Heterozyklen wie 1,3,4- Oxadiazol oder Phenylchinoxalin in die Polymerkette eines Poly(amidimid)s fiihrte zu einer erheblichen Verbesserung der Alkalistabilitat. Polyamide mit Imid-Ringen in der Seitenkette sind bestandiger gegen Hydrolyse als Polyamide mit Imid-Grup-pen in der Hauptkette.
    Notes: The stability of some heterocyclic poly(amide imide)s in acidic and alkaline medium was compared to the structurally related polyimide and poly(amide imide)s without other heterocyclic groups. All the polymers have high stability in acidic medium. The introduction of additional heterocycles such as 1,3,4-0xadiazole or phenylquinoxaline into the macromolecular chain of a poly(amide imide) increases substantially the resistance to alkaline medium. Polyamides containing imide rings only in the side chain are more stable to hydrolysis than related polyamide having imide units in the main chain.
    Additional Material: 4 Ill.
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    Synthesis and modification of a trifunctional epoxy resin with amino-terminated poly(dimethylsiloxane)s for semiconductor encapsulation (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 245 (1997), S. 125-137 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein trifunktionelles Hochleistungs-Epoxidharz auf Basis des Triglycidylethers von Tris(4-hydroxyphenyl)methane (TETM) wurde durch Kondensation von 4-Hydroxybenzaldehyd mit Phenol and anschließender Epoxidierung mit Epichlorhydrin hergestellt. Zur Strukturaufklärung wurde das Produkt mittels IR- und NMR-Spektroskopie sowie Masenspektrometrie untersucht. Durch Modifizierung mit einem aminoterminierten Poly(dimethylsiloxan) wurde die Eigenspannung des mit einem Phenolnovolak vernetzten TETM für die Anwendung als Verkapselung elektronischer Bauteile herabgesetzt. Durch das in der TETM-Matrix frei verteilte Silikonelastomere konnte die Spannung des vernetzten Epoxidharzes deutlich reduziert werden, indem der thermische Ausdehnungskoeffizient und der Elastizitätsmodul des Materials verringert wurden, während die Glasübergangstemperatur kaum abnahm.
    Notes: A high-performance trifunctional epoxy resin based on the triglycidyl ether of tris (4-hydroxyphenyl)-methane (TETM) was synthesized by the condensation of 4-hydroxybenzaldehyde with phenol followed by epoxidation with epichlorohydrin. The structure of TETM was confirmed by mass spectra, infrared and nuclear magnetic resonance spectroscopy. Amino-terminated poly(dimethylsiloxane)s were used to reduce the stress of the trifunctional epoxy resin cured with phenolic novolac resin for electronic encapsulation application. The dispersed silicone rubbers effectively reduce the stress of cured epoxy resins by reducing the coefficient of thermal expansion and flexural modulus while the glass transition temperature was hardly depressed.
    Additional Material: 6 Ill.
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    Cationic polymerization using allyl sulfonium salt. 3. Allyl sulfonium salt/ascorbate redox coupleFor parts 1 and 2 cf.8 and 9, respectively. (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 245 (1997), S. 149-154 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die kationische Polymerisation von Cyclohexenoxid wurde durch Reduktion eines Allylsulfoniumsalzes in Gegenwart von Ascorbyl-6-hexadecanoat und Kupfer(II)-benzoat ausgelöst. Für die Initiation wird eine Redoxreaktion diskutiert, in der die Kupferverbindung als Elektronenüberträger dient.
    Notes: The cationic polymerization of cyclohexene oxide was initiated by reduction of allyl sulfonium salt in the presence of ascorbyl-6 hexadecanoate and copper (II) benzoate. A redox reaction in which the copper compound serving as an electron carrier for the initiation step was proposed.
    Additional Material: 3 Ill.
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    Specialty polymeric membranes, 7. Pervaporation separation of benzene/cyclohexane mixtures with nylon 6-graft-poly(oxyethylene) membranes (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 245 (1997), S. 193-202 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Neuartige Membranmaterialien für die Auftrennung von Benzol/Cyclohexan-Gemischen wurden durch die Pfropfung von Nylon 6 mit Oligooxyethylenen wie Diethylenglykol, Poly(ethylenglykol) 200 (PEG200) und Polyethylenglykol 400 (PEG400) synthetisiert. Membranen aus derartig modifiziertem Nylon 6 zeigten eine Permselektivität gegenüber Benzol, wobei einige der Membranen ausschließlich für Benzol permeabel waren.
    Notes: Novel membrane materials for pervaporation separation of benzene/cyclohexane mixtures were prepared by the introduction of oligo(oxyethylene)s, such as diethylene glycol, poly(ethylene glycol) 200 (PEG200) and poly(ethylene glycol) 400 (PEG400) onto Nylon 6. The polymeric membranes from modified Nylon 6 thus prepared showed permselectivity toward benzene. Some membranes exclusively permeated benzene from benzene/cyclohexane mixture.
    Additional Material: 3 Ill.
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    Mitteilungen/Announcements (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 245 (1997), S. 211-212 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052450119
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    Allylic polymers from resin acids (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 246 (1997), S. 11-22 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Durch Diels-Alder Reaktion von aus Kolophonium gewonnenen Säuren mit Diallylmaleat wurde ein ungesättigtes Produkt erhalten, welches sowohl als Monomeres als auch als Vernetzer für Allylpolymere verwendet werden kann. Das Monomere und daraus hergestellte Polymere wurden mit üblichen chemischen und physikalischen Methoden charakterisiert. Die Polymeren haben eine lineare Struktur, möglicherweise einhergehend mit intramolekularer Zyklisierung bei niedrigen Molekulargewichten, oder eine dreidimensionale Struktur bei hohen Umsätzen. Sie sind einigermaßen thermostabil.
    Notes: An unsaturated adduct has been synthesized by the Diels-Alder reaction between resin acids and diallyl maleate. The obtained polymerizable product can be used both as monomer in the formation of allyl polymers and crosslinking agent. The monomer and its polymers were investigated by usual physical and chemical methods. The synthesized polymers present a linear structure, possibly associated with intramolecular cyclization at low molecular weights, or a three-dimensional structure at high conversions. They are fairly thermostable substances with carboxylic groups in the polymer chain.
    Additional Material: 4 Ill.
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    Application of molecularly imprinted polymer as a drug retaining matrix (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 246 (1997), S. 65-69 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: 2-Hydroxyethylmethacrylat wurde mit Ethylenglycol-dimethacrylate in Gegenwart von Hydrocortison als Modellsubstanz mit Gamma-Strahlen copolymerisiert, wobei ein “molecular imprinted polymer” (MIP) erhalten wurde. Das Hydrocortison wurde mit Chloroform extrahiert und anschließend aus Methanol wieder absorbiert. Nach 30 Tagen Lagerung in einer Methanol/Wasser-Mischung (3:1 v/v) waren noch 96% des Hydrocortisons in der Matrix eingelagert. Im Vergleich zu Hydrocortison wird Testosteron nur in geringer Menge absorbiert.
    Notes: Copolymerization by gamma irradiation of 2-hydroxyethyl methacrylate with ethylene glycol dimethacrylate in the presence of hydrocortisone as model drug gave a molecular imprinted polymer (MIP). The hydrocortisone was removed from the matrix with chloroform and incorporated again from methanol solution. Release data show that 96% of the incorporated drug is retained after 30 days storage in a methanol/water (3 : 1 v/v) mixture. In comparison with hydrocortisone, only a small quantity of testosterone is absorbed by the matrix.
    Additional Material: 2 Tab.
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    Surface modification and bonding of poly(p-phenylene sulfide) (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 246 (1997), S. 97-107 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wird gezeigt, daß es sowohl durch Oxidation, z.B. mittels Essigsäure/Wasserstoffperoxid oder Chromschwefelsäure, als auch durch Plasmabehandlung möglich ist, auf Poly(p-phenylensulfid) (PPS)-Oberflächen polare Gruppen einzuführen. Die änderungen and den PPS-Oberflächen wurden mit FTIR-Spektroskopie, Röntgen-Photoelektronenspektroskopie und Kontaktwinkelmessungen verifiziert. Die verbesserte Adhäsion der behandelten Oberflächen wurde mit Hilfe von Zug-Scher-Messungen nach dem Verkleben mit Acrylatklebstoffen quantitativ erfaßt. Die Untersuchung der Oberflächen mittels AFM (Atomic Force Microscopy) zeigt, daß die verbesserte Adhäsion auch durch eine größere Oberflächenrauhigkeit als Folge der Oberflächenbehandlung erreicht wird. Dieser Effekt ist besonders deutlich bei Proben, die mit Chromschwefelsäure behandelt wurden.
    Notes: It is demonstrated that both chemical oxidation, e.g. by using acetic acid/hydrogen peroxide or chromosulfuric acid, and plasma treatment of poly(p-phenylene sulfide) (PPS) surfaces introduce polar groups. The changes of the surface chemistry are detected by FTIR spectroscopy, X-ray photoelectron spectroscopy, and contact angle measurements. The increased polarity is partially responsible for better adhesion as verified by lap shear measurements using acrylic adhesive. Another important contribution to the improved adhesion originates from increased surface roughness after surface modification as measured by atomic force microscopy. This effect is very pronounced for PPS surfaces treated with chromosulfuric acid.
    Additional Material: 4 Ill.
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    Die chemische Beständigkeit eines Steinschutzstoffes auf Polyurethanbasis in der künstlichen Bewitterung (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 246 (1997), S. 169-181 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The durability of a polyurethane-based coating material, used as protecting agent on Sander Sandstone, is investigated after different periods of artificial weathering in an environment simulation chamber (VENUS) by means of surface-sensitive methods (ESCA, infrared spectroscopy) and gel permeation chromatography. Only the outermost 4 millimeters showed decay on the polyurethane-chemistry level.
    Notes: Die Dauerhaftigkeit eines Steinschutzstoffes auf Polyurethanbasis im Sander Schilfsandstein gegenüber chemischen Angriffen wurde nach verschieden langen Bewitterungszeiten in einer Versuchsanlage zur naturnahen Umweltsimulation untersucht. Dabei wurden sowohl die Gelpermeationschromatographie (GPC) als auch oberflächensensible Analysenmethoden (XPS und PAS-FTIR) zur Untersuchung der Polyurethan-Mikroschicht im Stein eingesetzt. Nur im Bereich der ersten vier Millimeter Gesteinstiefe konnten bewitterungsbedingte chemische Veränderungen des Polymeren festgestellt werden.
    Additional Material: 8 Ill.
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    Charakterisierung von vernetzten Polymeren, 9a. Verfolgung der Nachvernetzung von Poly(styrol-co-divinylbenzol) zu feinporigen Adsorberpolymeren (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 246 (1997), S. 137-168 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The post-crosslinking of chloromethylated poly(styrene-co-divinylbenzene) to highly crosslinked, porous adsorbent polymers has been studied over a wide range of reaction temperature (50-80°C) and reaction time (up to 24.5 h). The crosslinked materials were characterized by nitrogen adsorption/desorption, mercury porosimetry, determination of the chlorine content, swelling measurements, pyrolysis gas chromatography, and Fourier transform infrared spectroscopy.Surface area, pore size distribution, pore volume, chlorine content, swelling degree, selected peak ratios in the pyrograms and in the FTIR spectrograms are shown to be clear functions of the post-crosslinking time. Therefore the post-crosslinking process can be monitored by physical as well as by chemical characterization methods.Moreover, information on the chemical homogeneity or inhomogeneity of the chloromethylated copolymers and the porous adsorbent polymers can be derived from the swelling and pyrolysis gas chromatographic results. Application of different solvents in the swelling experiments enables the construction of swelling diagrams. Based on these swelling diagrams, the anomalous swelling behaviour of adsorbent polymers during the post-crosslinking can be explained.The surface area and pore volume strongly increase with progressing post-crosslinking, and well-defined correlations between sample texture, pyrolysis and FTIR data are found. In general, changes of physical properties can be attributed to the chemical modification of the material due to the post-crosslinking.
    Notes: Die Nachvernetzung von chlormethyliertem Poly(styrol-co-divinylbenzol) zu hochvernetzten porösen Adsorberpolymeren wurde über einen weiten Temperatur-(50-80°C) und Reaktionszeitbereich (bis zu 24,5 h) untersucht. Die vernetzten Materialien wurden durch Stickstoffadsorption/Desorption, Quecksilberporosimetrie, Bestimmung des Chlorgehalts, Quellungsmessungen, Pyrolyse-Gaschromatographie und Fourier-Transform-Infrarotspektroskopie charakterisiert.Die Oberfläche, die Porengrößenverteilung, das Porenvolumen, der Chlorgehalt, ausgewählte Peakverhältnisse in den Pyrogrammen und den FTIR-Spektrogrammen sind eindeutige Funktionen der Nachvernetzungszeit. Der Nachvernetzungsprozeß kann somit sowohl mit physikalischen als auch mit chemischen Charakterisierungsmethoden verfolgt werden. Darüber hinaus ermöglichen Quellungsmessungen und pyrolysegaschromatographische Untersuchungen Aussagen zur Homogenität und Inhomogenität der chlormethylierten Copolymeren und porösen Adsorberpolymeren.Der Einsatz verschiedener Lösungsmittel bei der Quellung erlaubt die Konstruktion von Quellungsdiagrammen, anhand derer das anomale Quellungsverhalten der Adsorberpolymeren während der Nachvernetzung erklärt werden kann.Im Verlauf der Nachvernetzung werden die Oberfläche und das Porenvolumen stark vergrößert und eindeutige Korrelationen zwischen der Probentextur und den Pyrolyse- und FTIR-Daten gefunden. Die Veränderung der physikalischen Eigenschaften im Verlauf der Vernetzung kann generell auf die chemische Modifikation des Materials zurückgeführt werden.
    Additional Material: 14 Ill.
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    The influence of flame retardant structure on UV stabilization approaches in polypropylene (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 247 (1997), S. 61-72 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: UV stabilization of polymer systems containing brominated flame retardants has proven to be a difficult technical challenge. Generation of acidic products during processing or exposure can cause a catastrophic deactivation of the Hindered Amine Light Stabilizer (HALS). An understanding of the mechanism for bromine generation from aliphatic and aromatic based flame retardants has lead to formulation approaches based on flame retardant structure. In formulations containing aromatic brominated flame retardants, combinations of UV absorbèrs and a new class of siloxane HALS provide the highest level of UV stabilization to date. Alternatively, bicomponent fiber spinning technology can also provide outstanding UV resistance at significantly lower levels of stabilizers than that used in the monocomponent formulation approach.
    Additional Material: 11 Ill.
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    Oxidation kinetics of poly(4-methylpentene) (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 247 (1997), S. 73-89 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermal oxidation (in air between 70 and 150°C) of unstabilised camples of poly(4-methylpentene) (PMP) were studied by infrared spectrometry and by gravimetry. The behaviour was compared to PP exposed in the same conditions.The thermal oxidation was found to exhibit two well differentiated kinetic regimes both for PP as for PMP. The first regime predominates at temperature higher than 90°C. It is characterized by an activation energy of the pseudo induction period of about 100 kJ mol-1. The induction period of mass gain is about 1,8 time shorter than the induction period of carbonyl gain. These characteristics, and the fact that induction periods are of the same order for both polymers, are consistent with a «close loop mechanistic» scheme with unimolecular POOH decomposition. The advantages of this hypothesis compared to other proposed hypothesis (bimolecular POOH decomposition, heterogeneous oxidation...) are discussed. The main theoretical difficulty is that of explaining why the unimolecular process predominates, whereas POOH are obviously hydrogen bonded, even at very low conversions of the oxidation process. This point remains to be explained.The second kinetic regime predominates at temperature lower than 90°C. It is characterized by a considerably lower activation energy. We have examined many hypothesis to explain the existence of a transition at that temperature (where neither PMP nor PP display a physical transition). A first hypothesis is that unimolecular POOH decomposition is replaced by a bimolecular one, which can explain a decrease of the apparent activation energy of about 50%. The bimolecular initiation creates pairs of radicals (POO·+ PO·). It can be imagined that a part of them desactivate mutually by termination after rearrangement of PO· by β scission. In this case, the transition at 90°C could be also a result of the temperature induced change in molecular mobility. Above 90°C, the radicals would diffuse almost freely out of the cage. In contrast, below 90°C, termination would become competitive with diffusion. A supplementary research is needed to fully elucidate the cause of this transition at 90°C.The eventuality of the existence of spatial heterogeneity of the oxidation process has been discussed. It is well known that oxidation is heterogeneous at the morphological scale, but there is no evidence of heterogeneity at smaller scale, where the chemical kinetic would not be applicable.
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    Thermal degradation of polystyrene in different environments (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 247 (1997), S. 179-195 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Several aspects of the thermal degradation of polystyrene are highlighted in this communication. The factors involved in determining the ratio of volatile to tar fraction products in the degradation of the pure polymer are examined, leading to the conclusion that the initial melt viscosity plays an important role in determining the balance between intra- and intermolecular transfer. The effect on the degradation of polystyrene of the presence of a second polymer is discussed. For polystyrene-polybutadiene and polystyrene-polyisoprene blends, stabilisation is observed, which is attributed to radical scavenging. The thermal degradation behaviour of polystyrene in the presence of oxygen has been investigated, with and without an antioxidant additive. Products have been characterised for oxidative conditions and the kinetics of degradation have been studied.
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    Controlled degradation in tailor-made macromolecules elaboration. Controlled chain-cleavages of polydienes by oxidation and by metathesis (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 247 (1997), S. 197-211 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A chain cleavage reaction allowing the transformation of high molecular weight polymers in well-defined oligomers can be considered as a step in a synthetic scheme. The control of oligomers with respect to their average molecular weights, their molecular weights distributions and their chain-end microstructures implies the control of the cleavage reaction with respect to its yield, its regiospecificity and its chemiospecificity. Among several examples of efficient uses of this principle for the preparation of liquid oligomers from unsaturated polymers, attention is focused (I) on controlled oxidative degradation of rubber and (II) on metathetical controlled degradation of 1,4-polydienes and polyakenamers. (I.a) The mechanism of the phenylhydrazine accelerated oxidation of rubber in the latex phase is described according to accurate structural studies on molecular model molecules. (I.b) The epoxidation of rubber and periodic acid cleavages of epoxides in the latex phase are interpretated referring to the influence of the biphasic medium. The results are in agreement with interfacial blocky epoxidation by the water-soluble reagent and interfacial arrangement of the epoxidized block to be cleaved. Finally the metathetical degradations resulting from back-bitting cyclisation and cross metathesis with acyclic alkenes are presented as preparative methods to get (II.a) well-defined cyclic oligomers and (II.b) telechclic oligomers (i.e. terminally functionalized oligomers).
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    Chemiluminescence in thermal oxidation of ABS (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 247 (1997), S. 255-268 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two concepts in the chemiluminescence research-the heterogeneous model and the kinetic approach-are discussed. The analysis of published data obtained by a highly sensitive photon-counting system reveals the contradictory nature of the heterogeneous model and proves its inconsistency. On the other hand, the kinetic approach has been successfully applied to evaluation of thermal oxidation in a variety of systems, ABS compositions in particular. Emulsion grade ABS were found to be essentially less stable than ionic mass polymerization products. Among the antioxidants studied, Santonox R is clearly more efficient than Irganox 1076. In emulsion grades the superiority of Santonox R to Irganox 1076 is reflected primarily in larger induction period, while in ionic resin it is mostly due to smaller oxidation rate constant values. The introduction of UV stabilizers by themselves has no influence on durability in either ionic or emulsion resins. Similarly to systems without UV stabilizers, Santonox R is more efficient than Irganox 1076 in mixtures with UV stabilizers as well. The comparative study of various ABS-coloring agent compositions by chemiluminescence and DSC reveals much greater sensitivity of the former. While DSC lets one make only a trivial conclusion that the introduction of an antioxidant improves stability, chemiluminescence shows the differences in durability as large as 3 to 4 times for the samples DSC fails to distinguish. In addition, chemiluminescence furnishes a significant insight on the factors affecting stability. The DSC thermal oxidative stability data can be related to resistance to oxidation during processing, whereas the chemiluminescence results are expected to be useful in predicting materials' lifetime at service temperatures.
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    Mechanical properties of poly(propylene) filled with calcium carbonate of various shape (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 248 (1997), S. 73-83 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Mit Alkyldihydrogenphosphaten behandeltes Calciumcarbonat unterschiedlicher Teilchenform (sphärisch, kubisch, Nadeln) wurde als Füllstoff für Polypropylen (PP) verwendet. Der Einfluß der Kettenlänge der Alkylgruppe auf mechanische Eigenschaften (Zugdehnung, Zugfestigkeit, Schlagzugfestigkeit, Streckspannung) und die Adhäsion zwischen der PP-Matrix und den verschiedenen CaCO3-Teilchen wurde untersucht, ebenso der Einfluß der Teilchenform auf den Speichermodul des mit unbehandeltem CaCO3 gefüllten und verstreckten PP.Zugdehnung, Schlagzugfestigkeit und Adhäsion des mit kubischem bzw. nadelförmigem CaCO3 gefüllten PP nehmen mit steigender Kettenlänge der Phosphat-Alkylgruppe zu, während das mit sphärischem CaCO3 gefüllte PP keine einheitliche Tendenz zeigt.Die relativen Moduli Edc/Edr (Edc - Speichermodul der verstreckten Komposite; Edr - Speichermodul der ungefüllten verstreckten PP-Matrix) der verstreckten PP/CaCO3-Komposite lassen sich mit einer modifizierten Halpin-Tsai-Gleichung beschreiben, in der die Faktoren (i) Orientierung der Polymermatrix, (ii) Einfluß des Füllstoffes (Gehalt, Modul, Kantenverhältnis) und (iii) Hohlraumvolumen an der Grenzfläche Polymer-Füllstoff enthalten sind.
    Notes: Calcium carbonate of various particle shape (CaCO3, sphere, cube, needle) treated with alkyl dihydrogen phosphate ester (APEN, CnH2n+1OPO(OH)2, n = 1, 4, 8, 10, 12) and poly(propylene) (PP) were mixed on a two roll mill. The effect of carbon number of APEN on the mechanical properties (tensile elongation, tensile strength, impact strength, yield stress) and adhesion between PP matrix and various CaCO3 particles and the effect of CaCO3 shape on the storage modulus of elongated PP/CaCO3 has been investigated.The tensile elongation, impact strength and adhesion of PP-CaCO3 interface increased with carbon number of APEN (n ≦ 10) for needle and cube type, but the dependence of tensile properties on APEN carbon number is not clearly recognized for the sphere type.The relative storage moduli of elongated PP/CaCO3, Edc/Edr Edc - modulus of elongated PP/CaCO3 (untreated); Edr - modulus of elongated PP matrix could sufficiently be described with a modified Halpin-Tsai equation, which contains the factors of (i) polymer matrix orientation, (ii) particle effect (content, modulus, aspect ratio), and (iii) void volume at polymer-filler particle interface.
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    Permeability of CO2 through chitosan membrane swollen by water vapor in feed gas (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 248 (1997), S. 85-94 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In der vorliegenden Studie wurde die Permeation und Separation von Kohlendioxid durch eine wassergequollene Chitosanmembran untersucht. Die Chitosanmembran wurde durch in einem Trägergas enthaltenen Wasserdampf gequollen und zeigte nach dieser Behandlung eine hohe Gaspermeabilität. Bei Raumtemperatur durchdrang vorzugsweise Kohlendioxid die gequollene Chitosanmembran mit einer Permeabilität von 2,5·10-8 cm3 (STP) cm(s cm2 cmHg)-1 und einem CO2/N2 Trennfaktor von 70.Diese Trennleistung für Kohlendioxid wird durch die basischen Eigenschaften der Aminogruppen den Chitosanmolekülen hervorgerufen.Die Membranherstellungsbedingungen, wie zum Beispiel die Essigsäurekonzentration der Gießlösung, beeinflußten die Permeationsgeschwindigkeit. Der Einfluß der Arbeitstemperatur wurde ebenfalls untersucht. Um die Trennleistung der Membran zu erhöhen, wurden verschiedene Methoden der Membranbehandlung und Arbeitsbedingungen untersucht.
    Notes: The permeation and separation of carbon dioxide through a water-swollen chitosan membrane was studied. A chitosan membrane was swollen by water vapor contained in a feed gas and, thus treated, exhibited a large gas permeability. Carbon dioxide preferentially permeated through the swollen chitosan membrane with a permeability of 2.5·10-8 cm3 (STP) cm(s cm2 cmHg)-1 and a CO2/N2 separation factor of 70 at room temperature. This separation performance for CO2 resulted from the basic properties of the chitosan amino groups. The membrane preparation conditions, such as acetic acid concentration of the casting solution, affected the membrane permeation rate. The effect of the operation temperature was also measured. To increase the separation performance of the membrane, several methods of membrane treatment and operation were evaluated.
    Additional Material: 6 Ill.
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    Modifizierung von Faseroberflächen durch die permanente Fixierung supramolekularer Komponenten, Teil 1: GrundlagenAuszug aus der eingereichten Dissertation von U. Denter, Universität Duisburg 1997. (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 248 (1997), S. 153-163 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: A new conception for modification of textile surfaces by permanent fixation of supramolecular components is explained. The principle of selective complexation is illustrated. Cyclodextrins, aza crown ethers, calixarenes, cyclotriveratrylenes and fullerenes are mainly suggested as suitable ligands for that procedure. The chemical structure and the complexation behaviour of the substances are described. Some surface properties which may be obtained with the ligands are especially emphasized.
    Notes: Ein neues Konzept zur Modifizierung von Faseroberflächen durch permanente Fixierung supramolekularer Verbindungen wird vorgestellt, und das Prinzip der selektiven Komplexierung wird erklärt. Als für die Behandlung grundsätzlich geeignete Liganden werden insbesondere Cyclodextrine, Azakronenether, Calixarene, Cyclotriveratrylene und Fullerene hinsichtlich ihrer chemischen Struktur sowie ihrer komplexierenden Eigenschaften beschrieben. Einige erreichbare Oberflächeneffekte werden hervorgehoben.
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    New preparation method of poly(amide-imide)s using direct polycondensation with thionyl chloride and their characterization (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 248 (1997), S. 105-122 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein neues, wirtschftliches Verfahren zur Herstellung hochmolekularer Poly(amidimid)e (PAIs) basiert auf der direkten Polykondensation von Trimellitsäureanhydrid(TMA) oder Diimid-Disäuren (DIDAs) mit aromatischen Diaminen in Gegenwart von äquimolaren Mengen an Thionylchlorid in N-Methylpyrrolidon bei relativ niedrigen Temperaturen. Die Polyamidierung von Diimid-Disäuren und Diaminen zu Kopf-Kopf-Polymeren (H-PAIs) ist temperaturempfindlich und verläuft rasch; die Reaktionsdauer von 1 h war für die vollständige Umsetzung ausreichend. Der höchste Wert für die inhärente Viskosität ηinh wurde mit 72 mL g-1 bei Polymerisation bei Raumtemperatur erzielt. Durch die Polykondensation von TMA mit Diaminen und anschließende Imidisierung nach verschiedenen Methoden, wie die azeotrope Dehydrierung bzw. die Festphasenimidisierung von Polyamsäuren oder der Einsatz von Triphenylphosphit als Cokondensationsagens, wurden ebenfalls einige statistisch aufgebaute Polymere (R-PAJs) hergestellt. Von den Imidisierungsmethoden ergab die Festphasenimidisierung von Polyamsäuren mit inhärenten Viskositäten ηinh von 58-85 mL g-1 zufriedenstellende Ergebnisse. Imidisierungsgrade und Molekulargewichte wurden im wesentlichen von der Lösungsmittelmenge sowie der Imidisierungstemperatur und -zeit bestimmt. Sowohl H-PAI als auch R-PAI zeigten gute mechanische Eigenschaften, je nach Ausgangsmonomeren lagen die Zugfestigkeiten im Bereich 118-131 MPa und die Glasübergangstemperaturen im Bereich von 263-299°C. Die Schmelzviskositäten der PAIs bewegten sich zwischen 7,4·103 und 4,5·103 Pa s für H-PAI bzw. R-PAI und sind mit dem Wert fur konventionelles PAI, Torlon® 4000T, von 5,6·103 Pa s vergleichbar.
    Notes: A study for the development of a new, economical manufacturing process for high-molecular-weight poly(amide-imide) (PAI) was performed via direct polycondensation of trimellitic acid anhydride (TMA) or diimide diacids (DIDAs) with aromatic diamines using an equimolar amount of thionyl chloride in NMP at relatively low temperatures. The polyamidation of DIDAs and diamines for head-to-head polymers (H-PAIs) was sensitive to the reaction temperature and proceeded very quickly, 1 h was sufficient to complete the reaction. The highest value of inherent viscosity, ηinh, of 72 mL g-1 was obtained by polymerization at room temperature. Also several randomly sequenced polymers (R-PAIs) were prepared by polycondensation from TMA and diamines, followed by imidization with various methods, such as using TPP as a co-condensing agent, azeotropic dehydration of polyamic acid (PAA) and solid-state imidization from PAA. Solid state imidization from polyamic acids at 235°C gave satisfactory results with an inherent viscosity 58-85 mL g-1. Solvent content, imidization temperature and time were major controlling factors for the degree of imidization as well as for the molecular weight. Both H-PAI and R-PAI showed good mechanical properties with tensile strength of 118-131 MPa and Tg ranged between 263-299°C depending on the nature of monomers. The melt viscosity of the PAIs ranged between 7.4 · 103 and 4.5 · 103 Pa s for H-PAI and R-PAI respectively. These values are comparable to that of conventional PAI, Torlon® 4000T of 5.6 · 103 Pa s.
    Additional Material: 3 Ill.
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    MITTEILUNGEN/ANNOUNCEMENTS (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 248 (1997), S. 217-217 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052480114
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    Carbon fibre oxidation, textural and surface changes (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 248 (1997), S. 201-215 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In dieser Arbeit werden die durch Oxidation mit Salpetersäure hervorgerufenen Veränderungen der spezifischen Oberfläche, Porosität, Oberflächenfunktionalität und der Faserdimensionen handelsüblicher Kohlenstoffasern untersucht. SEM-Untersuchungen ergaben keine Veränderungen, jedoch konnten durch Kryptonadsorptionsmessungen erhöhte spezifische Oberflächen-und Mikroporositätswerte nachgewiesen werden.Die oxidative Behandlung beeinträchtigt die Faserlänge und verringert, wenn auch nur geringfügig, den Faserdurchmesser und die Festigkeit, wie aus Messungen des Elastizitätsmoduls hervorgeht.Die durch volumetrische Messungen und XPS durchgeführte Funktionalitätsanalyse zeigt eine erhöhte Gesamtoberflächenazidität aufgrund einer Zunahme der Carboxygruppen. Längere Behandlung der Fasern vermindert den Gehalt an Hydroxygruppen an der Faseroberfläche.
    Notes: This work reports on the variations in specific surface, porosity, surface functionality and dimension of commercial carbon fibre subjected to oxidative treatment with nitric acid. Scanning electron microscopy (SEM) observation did not reveal any topographic changes on the fibres, although crypton adsorption evidences increases in specific surface and microporosity.Oxidative treatment has an effect on fibre length, although it also slightly reduces the fibre diameter and the fibre strength, as measured in terms of the elastic modulus.Functional analysis by means of volumetric measurements and X-ray photoelectron spectroscopy (XPS) reveals an increase in the overall fibre surface acidity through carboxy group increase. Prolonged treatment gradually removes hydroxy groups from the fibre surface.
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    Influence of emulsifier and initiator concentration on the copolymerization of 1,4-divinylbenzene with comonomers of different solubility in water (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 246 (1997), S. 183-201 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß der Konzentration von Natriumdodecylsulfat und von 2,2′-Azoisobutyronitril auf die vernetzende Emulsionscopolymerisation von 1,4-Divinylbenzol mit hydrophobem Cyclohexylmethacrylat und mit hydrophilem Methylacrylat wurde untersucht. Um festzustellen, welche Rolle die Diffusion von Monomeren bei der Copolymerisation spielt, wurden die Emulsionen durch gemeinsame und getrennte Solubilisierung hergestellt. Der Monomerumsatz wurde bestimmt. Die erhaltenen Microgele wurden bezüglich Molmasse, Teilchendurchmesser und Grenzviskositätszahl charakterisiert. Beim übergang von einer normalen zu einer mizellaren Emulsion war der Umsatz maximal. Mit dem hydrophoben Comonomeren bildete sich bei Verringerung der Emulgatormenge zunehmend unlösliches Koagulat aus polymerisierten Monomertröpfchen. Mit höherer Emulgatorkonzentrationen entstand zunehmend unlösliches Agglomerat durch Reaktion von Mikrogelteilchen miteinander.
    Notes: The influence of the concentration of sodium dodecylsulfate and 2,2′-azoisobutyronitrile on the crosslinking emulsion copolymerization of 1,4-divinylbenzene with hydrophobic cyclohexyl methacrylate and with hydrophilic methyl acrylate was studied. The emulsions were prepared by joint and by separate solubilization to study diffusion effects. Monomer conversion was measured and the microgels were characterized by molar mass, particle size diameter and intrinsic viscosity. The monomer conversion was maximal in the transition from a normal to a micellar emulsion. With the hydrophobic comonomer increasingly insoluble coagulates from polymerized monomer droplets were formed on decreasing the emulsifier concentration. Toward higher emulsifier concentration increasingly insoluble agglomerates were formed by reactions between microgels.
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    Effect of accelerated exposure conditions on the photodegradation of BPA polycarbonate/ABS blends (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 247 (1997), S. 1-18 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A BPA polycarbonate/ABS blend containing 2% TiO2 was exposed to xenon are irradiation under SAE J 1885 conditions (quartz/borosilicate filters). “CRD” conditions (borosilicate/borosilicate filters), and ASTM D4459-86 conditions (borosilicate/soda lime filters). The results are consistent with the conclusion that polycarbonate dominates the photochemistry of polycarbonate/ABS blends under SAE J1885 and CRD xenon are exposure conditions. Exposure under ASTM D4459-86 conditions produced results similar to CRD conditions with some additional contribution attributable to the ABS component. The “activation spectrum” of PC/ABS blends under CRD conditions closely resembled the sum of the activation spectra of ABS and PC determined under similar conditions. The well-known change in mechanism that occurs when polycarbonate is exposed to light with wavelengths 〈 300 nm was manifested by increased rates of yellowing, surface erosion. and loss of gloss under SAE J 1885 conditions. Because of the mechanism change, testing under quartz/borosilicate filtered xenon are exposure cannot be considered to be appropriate for polycarbonate-containing formulations.
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    Degradation of ultra high molecular weight polyethylene in vivo (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 247 (1997), S. 31-43 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mechanical and thermal oxidation of UHMWPE used in the preparation of prosthetic implants is studied and the mechanisms of degradation are reported. Oxidation of new and retrieved prosthetic implants are studied by IR microscopy and clear evidence of oxidation in vivo is shown.
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    Mechanical and morphological properties of stabilized and non-stabilized HDPE films versus exposure time (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 247 (1997), S. 91-110 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Non UV-stabilized and UV-stabilized (a UV-absorber) HDPE films were photo-oxidized in a Xenotest. The concentration of carbonyl and the UV-stabilizer, the molecular weight, the crystallinity and the density were studied versus exposure time. Furthermore, the mechanical behaviour was studied at different strain rates by tensile testing.The number of chain scissions was found equal to the number of carbonyl groups. The density of the film increased from 950 to 970 kg/m3 and the crystallinity from 70 to 82%. The increase in density is explained by the increase in crystallinity and by oxygen uptake.The rate at which carbonyl groups are formed, was found to accelerate with exposure time. This acceleration finally resulted in profiles, which could be measured by FT-IR and verified by computer simulations.After 14 days of exposure the specimen failed in a brittle manner. An activation volume was calculated and found to decrease. It is thought that a change in molecular mobility is responsible for the lower strain at yield values. The change in molecular mobility can also explain the increase in Young's modulus with the strain rate and exposure time. The Takayanagi and the Halpin/Tsai models were used to describe the increase of modulus of elasticity.
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    Applicability and limitations of current lifetime prediction models for thermoplastics pipes under internal pressure (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 247 (1997), S. 131-145 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Engineering thermoplastics, in particular polyolefins such as special grades of poly(ethylene), are gaining importance in pipe applications such as gas and water supply systems. To ensure proper performance of such pipes over the required lifetime, polymer physics and mechanics concepts are needed to adequately account for the effects of time, temperature, and environmental conditions as well as the occurrence of pipe defects and imperfections on relevant polymer properties and pipe performance. This article provides a critical overview of the scientific background of current methodologies to describe the long-term behavior of thermoplastic pressure pipes. In particular, the merits and limitations of two different approaches-namely, the standard extrapolation method (SEM) described in ISO/TR 9080 and the linear elastic fracture mechanics (LEFM) approach-are compared. Special attention is given to effects associated with material ageing and degradation.
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    Polymers degradable under environmental conditions through end-modification of poly(α-methylstyrene) derivatives (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 247 (1997), S. 163-178 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: To induce degradabilities in polymers in response to environmental conditions, the end-modification reactions of poly(α-methylstyrene) derivatives were carried out. When diphenylphosphine chloride was used as a modifier for the living end of para-substituted PMS, the coupling efficiency was ca. 50%. 2-Phenylallyl halide derivatives such as 2-phenylallyl bromide, 2-(4-tolyl)allyl bromide, and α-trifluoromethylstyrene were found to be suitable end-modification agents. For example, ω-2-phenylallyl PMS was prepared with almost quantitative functionality by the reaction of the living PMS with 2-phenylallyl bromide. In a similar way, ω-3,3-difluoro-2-phenylallyl and ω-2-(4-tolyl)allyl PMS derivatives were synthesized. Based on thermogravimetric analysis, onset of the degradation temperature of the end-modified PMS derivatives decreased in the following order: ω-hydrogen- 〉 ω-3,3-difluoro-2-phenylallyl- 〉 ω-2-phenylallyl- 〉 ω-2-(4-tolyl)allyl-PMS. Actually, the onset temperature of ω-2-(4-tolyl)allyl-PMS derivatives was 50°C lower than that of ω-H-PMS derivatives. These results indicate that the active species is produced effectively at the end unsaturated bond, which initiates the depolymerization of the polymer at rather low temperatures. Ionic degradation of these polymers was also investigated using butyllithium as an anionic initiator and methanesulfonic acid as a cationic initiator. Tendencies similar to the thermal degradation were observed. Therefore, it is concluded that a 2-phenylallyl substituent at the end of the PMS chain induces effective degradation through several mechanisms such as radical, anionic and cationic depolymerization reactions.
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    Complexity of the hydrolytic degradation of aliphatic polyesters (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 247 (1997), S. 239-253 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Aliphatic polyesters are more or less hydrolytically degradable, depending on their chemical, configurational and morphological structures. Hydrolysis can be either homogeneous or heterogeneous, depending on many structural and environmental factors. The present understanding of this hydrolytic degradation is recalled. The importance of diffusion-reaction phenomena is discussed on the basis of the behaviors of polyesters derived from α-hydroxy acids, namely lactic and glycolic acids and attempts are made to extend the understanding to other members of the aliphatic polyester family. The main results of some recent investigations of the effects on poly(lactic acid) polymers of basic additives and of initiators such as stannous octoate and zinc metal, which are now industrially used, are presented.
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    Reactions and kinetic modelling of silicone-carbon resins (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 248 (1997), S. 1-21 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Berechnung der mittleren Molekulargewichte einer idealen, nichtlinearen, stufenweise ablaufenden Polymerisation von Comonomeren mit mehreen reaktiven Zentren im B-Zustand vor der Gelierung wird beschrieben. Ein kinetisches Modell wird angewendet, um den Verlauf der Polymerisation unter Berücksichtigung der Massenverhältnisse der möglichen, unterschiedlich substituierten Verbindungen zu simulieren. Die Molekulargewichte werden entweder durch Anwenden der Miller-Macosko-Methode oder durch Lösen der Diffentialgelicheungen für die Polymerisation von Verbindungen mit niedrigem Molekulargewicht erhalten. Die Näherung wird angewendet auf die mit Platin katalysierte Hydrosilylierung von methylsubstituiertem Cyclosiloxan mit Dicyclopentadien zu einem Hochleistungs-Silikon-Kohlenstoff-Harz. Die Näherung ergibt die Konzentrationen und Molekulargewichte der verschiedenen, zu jedem beliebigen Zeitpunkt der Reaktion vorhandenen Verbindungen. Unterschiedliche Arten der Monomeraddition können ebenfalls simuliert werden.
    Notes: This paper aims to calculate the average properties of ideal non-linear stepwise polymerization of comonomers containing multiple reacting sites at the B-stage prior to gelation. A kinetic model is used to simulate the polymerization process taking into account the mass balances of differently substituted species possible. The molecular weights are obtained either by the use of the Miller-Macosko method or by solving the differential equations for the polymerization of low-molecular-weight species. The approach is applied to the Pt-catalyzed hydrosilation reaction between methyl-substituted cyclosiloxane and dicyclopentadiene which produces a high-performance silicone-carbon. resin. The approach gives the concentrations of various species present at any given time and the molecular weights. Different modes of monomer addition can also be simulated.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052480101
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    Preparation and characterization of copolymers from methyl methacrylate and cardanyl methacrylate (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 248 (1997), S. 95-104 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Copolymere aus Methylmethacrylat (MMA) und Cardanylmethacrylat (CMA) wurden synthetisiert, charakterisiert und hinsichtlich ihre physikomechanischen Eigenschaften untersucht. Die mit Benzoylperoxid initiierte Copolymerisation wurde mit unterschiedlichen Anteilen von CMA(0,02-0,01 mol/mol) im Reaktionsansatz bei 80°C durchgeführt. Die Strukturen der Copolymeren wurden mit FTIR- und 1H-NMR-Spektroskopie charakterisiert. Die thermische Stabilität der Copolymeren wurde mit dynamischer Thermogravimetrie bestimmt. Es zeigte sich, daß die thermische Stabilität der Polymeren durch den Einbau von CMA in die MMA-Hauptketten verbessert wird.
    Notes: Copolymers of methyl methacrylate (MMA) and cardanyl methacrylate (CMA) were synthesized, characterized and their physico-mechanical properties were investigated. The benzoyl peroxide-initiated copolymerization was carried out by using different mole fractions of CMA (0.02-0.10) in the initial feed at 80°C. Structural characterization of copolymers was done using FTIR and 1H NMR spectroscopic techniques. The thermal stability of the copolymers was evaluated using dynamic thermogravimetry. Incorporation of CMA in the MMA backbone leads to an improvement in thermal stability.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052480106
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    Study on the kinetics of interfacial polycondensation for polyarylate (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 248 (1997), S. 123-137 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Kinetik der Polyarylastynthese durch Grenzflächenpolykondensation von Bisphenol A mit Tere-/Isophthalsäuredichlorid wurde durch UV-spektrometrische Verfolgung der Bisphenolatkonzentration in der wäßrigen Phase untersucht. Der Reaktionsmechanismus besteht aus drei Schritten, von denen der dritte Schritt geschwindigkeitsbestimmend ist: 1. Transport von Bisphenolat in der wäßrigen Phase; 2. Transfer von Bisphenolat durch die Grenzschicht und Transport in der organischen Phase; 3. Reaktion von Bisphenolat mit Säuredichlorid in der organischen Phase. Der Einfluß der Konzentration der Reaktanden in der wäßrigen bzw. organischen Phase und der Menge des Phasentransferkatalysators auf den Verlauf der Grenzflächenpolykondensation wurde untersucht.
    Notes: For the synthesis of polyarylate by interfacial polycondensation of bisphenol A with terephthaloyl/isophthaloyl dichloride, the kinetic mechanism was studied through the detection of the concentration of bisphenolate in the aqueous phase by UV spectrometry. The mechanism consists of three steps: 1. the transportation of bisphenolate in the aqueous phase, 2. the transfer of bisphenolate through the interface followed by its transportation in the organic phase, 3. the reaction of bisphenolate with the phthaloylic dichloride in the organic phase. The reaction of bisphenolate with the phthaloylic dichloride in the organic phase is the rate-determining step. The influence of the concentration in either the aqueous phase or the organic phase and of the quantity of the phase transfer agent on interfacial polycondensation were studied.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052480108
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    Preparation and properties of composites of kevlar-nomex copolymer and boehmite (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 248 (1997), S. 139-151 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein neuartiges organisch-anorganisches Hybridmaterial wurde durch den Einbau des Minerals Böhmit mittels eines Sol-Gel-Prozesses in ein Kevlar-Nomex-Copolymeres hergestellt. Durch Reaktion eines Gemisches aus m- und p-Phenylendiamin mit Terephthaloylchlorid und anschließender Umsetzung mit Aminophenyltrimethoxysilan wurden Poly(phenylenterephthalamid)-Ketten mit Aminophenyltri-methoxysilan-Endgruppen synthetisiert. In dieser Polymermatrix wurde die Hydrolyse der Alkoxygruppen einer Lösung von Aluminium-sec-butanolat in Butanol durchgeführt. Dadurch wurde ein chemisch an die Aramid-Ketten gebundenes anorganisches Netzwerk aufgebaut. Aus den hergestellten Hybridmaterialien mit unterschiedlichen Böhmit-Gehalten in der Aramidmatrix wurden Filme gegossen. Die Filme aus Hybridmaterial mit bis zu 15 Gew.-% Böhmit waren transparent gelb, während bei 20 und mehr Gew.-% Böhmit opake Filme erhalten wurden. Die mechanischen Eigenschaften dieser Filme wurden untersucht. Zugfestigkeit, Zugmodul, Härte und maximale Bruchdehnung nahmen mit steigendem Böhmitgehalt zunächst zu, vemngerten sich jedoch bei weiterer Erhöhung des Mineralanteils wieder. Der Zugmodul des Hybridmaterials bei 25°C lag zwischen 3,0 und 4,5 GPa. Die Materialien hielten einer maximalen Zugspannung von 252 MPa stand und zeigten Zersetzungstemperaturen von etwa 450°C. Die rnit DMTA ermittelten Werte für den Speichemodul lagen im Bereich 7,6-18,9 GPa. Das tan δ-Signal verbreiterte sich mit zunehmendem Böhmitanteil und ging bei hohen Böhmitgehalten in eine Schulter über. Die Signalpositionen des Verlustfaktors wurden infolge der zunehmenden sterischen Einschränkung der Segmentbewegungen rnit steigendem anorganischen Anteil zu höheren Temperaturen verschoben.
    Notes: A new organic-inorganic hybrid material was prepared by incorporating boehmite into a Kevlar-Nomex copolymer via a sol-gel process. Poly(phenylene-terephthalamide) chains having aminophenyltrimethoxysilane end groups were prepared by reacting a mixture of m-and p-phenylenediamine with terephthaloyl chloride, followed by end-capping with aminophenyltrimethoxysilane. The hydrolysis of the alkoxy groups of an aluminium sec-butoxide solution in butanol was carried out in the polymer matrix, thus creating an inorganic network structure combined chemically with the aramid chains. Hybrid materials containing different proportions of boehmite in aramid were thus produced and films were cast by solvent evaporation technique. These films with up to 15 wt.-% of boehmite were yellow and transparent, whereas the films with 20 wt.-% or more contents of boehmite were opaque. Mechanical properties of these films were analyzed. The values of tensile strength, initial modulus, toughness and maximum strain at rupture were initially found to increase and then decrease with further addition of boehmite. The tensile modulus of the hybrid material was found to be in the range of 3.0-4.5 GPa at 25°C. These ceramers were found to withstand maximum tensile stress of the order of 252 MPa, and the thermal decomposition temperature was around 450°C. The storage modulus as measured using DMTA was in the range of 7.6-18.9 GPa. The tan δ peak which in general became broader with increasing boehmite content showed a shoulder for composites containing large amounts of boehmite. The position of the peaks shifted towards high temperature with the increase in the inorganic contents showing hindrance in motion with increasing boehmite contents.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052480109
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    Crystallization behavior of poly(propylene)/polyamide 1010 blends using poly(propylene)-graft-glycidyl methacrylate as compatibilizer (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 248 (1997), S. 189-200 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Blends aus Polyamid 1010 (PA 1010) und Polypropylen(PP) wurden mit oder ohne Zusatz von Polypropylen-Glycidylmethacrylat-Pfropfcopolymeren (PP-g-GMA) untersucht. Der Einfluß dieses Verträglichkeitsvermittlers auf die thermischen Eigenschaften und das Kristallisationsverhalten der Blends wurde mit Differentialkalorimetrie und Weitwinkel-Röntgenbeugung ermittelt. Die Ergebnisse zeigen, daß die Kristallisation von PA 1010 durch PP-g-GMA merklich beeinflußt wird. PP/PA 1010 (75/25)-Blends mit höheren PP-g-GMA-Gehalten weisen eine konkurrierende Kristallisation der Phasen bei der Kristallisationstemperatur des Polypropylens auf. Die Kinetik der isothermen Kristallisation wurde untersucht, um den Einfluß der Verträglichkeitsvermittlung auf die Keimbildung und den Mechanismus des Keimwachstums zu beurteilen. In PP/PA 1010 (25/75)-Blends wurde trotz hoher PP-g-GMA-Gehalte keine konkurrierende Kristallisation beobachtet.
    Notes: Polyamide 1010/poly(propylene) (PA1010/PP) blends were investigated with and without the addition of poly(propylene)-graft-glycidyl methacrylate (PP-g-GMA). The effect of the compatibilizer on the thermal properties and crystallization behavior was determined by differential scanning calorimetry and wide-angle X-ray diffraction. From the results it is found that the crystallization of PA 1010 is significantly affected by the presence of PP-g-GMA. PP/PA 1010 (75/25) blends containing higher amounts of PP-g-GMA show concurrent crystallization at the crystallization temperature of PP. Isothermal crystallization kinetics also were performed in order to investigate the influence of the compatibilized process on the nucleation and growth mechanism. In the PP/PA 1010 (25/75) blends, concurrent crystallization behavior was not observed, even though the amount of PP-g-GMA was high.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052480112
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    Mechanical properties-structure relationships of crosslinked blends based on LDPE/HDPE waste (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 249 (1997), S. 47-57 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aus Abfällen von Polyethylen niedriger Dichte (LDPE) und Polyethylen hoher Dichte (HDPE) mit unterschiedlichen Abbaugraden wurden Blends hergestelt und deren strukturelle, mechanische und rheologische Eigenschaften untersucht. Durch die Zumischung von 2 Gew.-% Dicumylperoxid konnte sowohl die Zugfestigkeit als auch die Bruchdehnung der Proben verbessert werden, ohne daß sich die Schmelzelastizität der LDPE- bzw. HDPE-Abfälle und deren Blends gegenüber nichtmodifiziertem Material merkbar verringerte. Außerdem wurde durch DSC-Messungen eine verbesserte Kompatibilität zwischen LDPE und HDPE festgestellt.
    Notes: Low-density polyethylene (LDPE) waste was blended with high-density polyethylene (HDPE) waste of different degrees of degradation. Structural, mechanical and rheological properties of these blends were investigated. It was found that 2 wt.-% of dicumyl peroxide improves simultaneously the tensile strength and elongation at break without serious decrease of the melt elasticity of separate PE wastes and their binary blends in comparison with unmodified PE. It was shown by DSC analyses that modification of the blends leads to better compatibility between LDPE and HDPE.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052490104
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    Polymerization of butadiene and isoprene with the NdCl3 · 3TBP-TIBA catalyst system (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 249 (1997), S. 59-77 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Polymerisation von Isopren und Butadien mit dem NdCl3 · 3TBP-TIBA-Katalysatorsystem (TBP: Tributylphosphat, TIBA: Triisobutylaluminium) wurde mit einer sehr exakten experimentellen Technik detailliert untersucht. Die Einflüsse der Ausgangsmonomerenkonzentration, der Polymerisationstemperatur und der Katalysator- und Cokatalysatorkonzentrationen auf den Umsatz, die mittlere Molmasse, die Molmassenverteilung und die Mikrostruktur der Polymeren werden diskutiert und unter Berücksichtigung der durch Neodym-Atome mit endständigen Monomereinheiten der Polymerkette gebildeten Allyl-Komplexe erklärt. Die Untersuchungen ergaben für die Monomeren eine Reaktion erster Ordnung. Die berechnete Aktivierungsenergie (25.58 kJ mol-1) ist niedriger als für klassische Ziegler-Natta-Katalysatoren und zeigt die höhere katalytische Aktivität des eingesetzten NdCl3 · 3TBP-TIBA-Katalysatorsystems. Die Ergebnisse von GPC-Messungen weisen auf zwei mögliche aktive Zentren hin, von denen jenes mit Aluminium eine höhere Stabilität aufweist und die Umwandlung von “anti”-Allyl-Gruppen in “syn”-Allyl-Gruppen begünstigt. Der Gehalt der Polymeren an 1,4-cis-Einheiten wird hauptsächlich von der TIBA-Konzentration bestimmt. Der Katalysator geht jedoch keine übertragungsreaktionen ein, wie dies bei TIBA der Fall ist. Die Umsätze sind für Butadien aufgrund der ausgeprägteren Tendenz zur Bildung von Allyl-Komplexen mit Neodym-Atomen höher als für Isopren.
    Notes: The isoprene and butadiene polymerization processes with the NdCl3 · 3TBP-TIBA catalyst system (TBP: tributylphosphate, TIBA: triisobutylaluminium) are studied in detail using an original and very accurate experimental technique. The influences of the initial monomer concentration, the polymerization temperature and the catalyst and cocatalyst concentrations on the conversion, the average molar masses, the polydispersity and the microstructure of the polymers are discussed and explained considering the allylic complexes formed between the neodymium atom and the last monomer unit in the macromolecular chain. A first-order reaction with respect to the monomer was obtained. The calculated value of the activation energy (25.58 kJ mol-1) is lower than for classical Ziegler-Natta catalysts, thus demonstrating the higher catalytic activity of the NdCl3 · 3TBP-TIBA catalyst system used. Two types of active centers are possible, as confirmed by GPC data. One of them, which includes aluminium, is more stable and favors the transformation from “anti” allylic units to “syn” allylic units. Thus, the 1,4-cis unit content of the prepared polymers is mainly determined by the TIBA concentration. The catalyst does not react by transfer reactions as TIBA does. The obtained conversions are always higher for butadiene than for isoprene due to a higher tendency of the former to complexate with the neodymium atom and forming allylic complexes.
    Additional Material: 14 Ill.
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    Heat-shrinkable films based on polyolefin waste (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 249 (1997), S. 151-162 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polyethylen-Abfälle (LDPE, HDPE sowie Blends aus beiden) wurden energiereicher Gammastrahlung aus einer 60Co-Quelle ausgesetzt. Durch die so induzierte Vernetzung des Polyethylens konnte das Material zu Schrumpffolien verarbeitet werden. Die Zugfestigkeit der Proben konnte durch Erhöhung der Strahlendosis bis auf 20 Mrad entscheidend verbessert werden, wobei gleichzeitig auch die Bruchdehnung des meist zersetzten PE-Abfalls erhöht wurde. Außerdem wurde die Kompatibilität zwischen LDPE- und HDPE-Abfall verbessert. Alle untersuchten PE-Proben zeigten einen Memoryeffekt, nachdem das Material bei 130°C zu Folien gezogen, unter Spannung gekühlt und anschließend spannungslos erwärmt wurde. Das Ausmaß der Schrumpfung war abhängig vom Abbaugrad des eingesetzten PE-Abfalls und von der Strahlendosis.
    Notes: Polyethylene wastes (low-density polyethylene, high-density polyethylene and their binary blends) were subjected to high-energy radiation, using a 60Co gamma radiation source. The crosslinked materials thus obtained were processed to heatshrinkable films. Tensile strength could be sharply improved by increasing the dose up to 20 Mrad, simultaneously increasing the elongation at break of the most degraded PE waste. An increase of the degree of compatibility of LDPE and HDPE waste was also observed. All samples examined exhibit a “memory effect” after drawing at 130°C and cooling under tension followed by further heating under relaxed conditions. The value of shrinkage depended on the degree of degradation of the PE waste and on the irradiation dose.
    Additional Material: 6 Ill.
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    Simulation of the hydrolytic polymerization of ∊-caprolactam with bifunctional regulatorsResearch supported by Laboratory of Polymer and Molecular Engineering. Fudan University, P.R. China (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 250 (1997), S. 1-14 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein Modell zur Simulierung der Kinetik der hydrolytischen Polymerisation von ∊-Caprolactam mit bifunktionellen Molekulargewichtsreglern wird vorgeschlagen, um charakteristische Daten wie die Konzentrationen von Caprolactam, Endgruppen, ∊-Aminocapronsäre und cyclischem Dimeren sowie Umsatz, zahlen- und gewichtsmittlere Molekulargewichte und die Uneinheitlichkeit zu analysieren. Die anhand dieses Modells berechneten Werte stimmen gut mit den experimentellen Ergebnissen überein. Es wurde festgestellt, daß bei Verwendung bifunktioneller Säure als Regler mit zunehmender Reglerkonzentration die Uneinheitlichkeit abnimmt, während sich mit monofunktioneller Säure als Regler die Uneinheitlichkeit mit steigender Reglerkonzentration asymptotisch einem Wert von 2 nähert.
    Notes: A simulation model dealing with the kinetic behavior of the hydrolytic polymerization of ∊-caprolactam with bifunctional regulators has been proposed to analyse such characteristic data of the polymerization as the concentrations of caprolactam. endgroups, ∊-aminocaproic acid, cyclic dimer, and as well as conversion, number- and weight-average molecular weights, and polydispersity index. The calculated values based upon the model were found to be quite compatible with the observed values. It is found that the presence of more bifunctional acid leads to a lower equilibrium value of polydispersity index, unlike the case of monofunctional acid where the polydispersity index asymptotically reaches a value of 2, regardless of the amount of monofunctional acid initially added.
    Additional Material: 5 Ill.
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    Makrogelierung von Polyacrylsäuredispersionen durch Vernetzung (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 250 (1997), S. 67-83 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The reaction of poly(acrylic acid) dispersions with diglycidyl ether or dicarboxylic dichlorides as crosslinking agents leads to the formation of macrogels without shrinking of the original dispersions. The particles of the dispersion are stabilized by block copolymers and are about 100 nm in diameter. Micrographs of scanning electron microscopy of the freeze-dried gel show a three-dimensional network structure formed by the particles. The kinetics of the crosslinking reaction was studied by differential scanning calorimetry. A model is presented considering a partition equilibrium of the crosslinking agent between the disperse and the continuous phase and the influence of mass transport of the crosslinking molecules in the interior of the particle. By means of dynamic rheology it was shown that the macrogels obtained are the result of chemical crosslinking reactions between the particles. Frequency-dependent measurements of the dynamic modulus during the crosslinking reaction showed that the network formation is a reaction-controlled cluster-cluster aggregation process. Dynamic light scattering experiments indicate a dominating cluster fraction with sizes of about 1 to 2 l m just before the gel point. The evolution of clusters is described by a simple model based on a stochastic method. Catalytically active materials can be prepared by anchoring metal colloids within the polymer particle network.
    Notes: Mit Blockcopolymeren stabilisierte Polyacrylsäuredispersionen mit ca. 100 nm großen Partikeln führen bei Reaktion mit Diglycidylethern oder Disäuredichloriden als Vernetzer ohne Schrumpfung zur Bildung von Makrogelen. Rasterelektronenmikroskopische Aufnahmen zeigen das Vorliegen einer aus den Partikeln aufgebauten dreidimensionalen Netzwerkstruktur. Die Kinetik der Vernetzungsreaktion wurde mit Hilfe der Differential-Scanning-Kalorimetrie untersucht. Das aufgestellte Modell berücksichtigt ein Verteilungsgleichgewicht des Vernetzers zwischen disperser und kontinuierlicher Phase und geht von einem Stofftransportprozeß der Vernetzermoleküle in das Partikelinnere aus. Mit Hilfe dynamisch-rheologischer Messungen wurde gezeigt, daß das Gel ein kovalent vernetztes Gebilde darstellt. Frequenzabhängige Messungen der dynamischen Moduln während der Reaktion führten zu dem Schluß, daß sich das Partikelnetzwerk infolge einer reaktionskontrollierten Cluster-Cluster-Aggregation bildet. Mit Hilfe der dynamischen Lichtstreuung wurde festgestellt, daß kurz vor dem Gelpunkt eine Fraktion mit Clustergrößen um 1 bis 2 μm dominiert. Die zeitliche Entwicklung dieser Gebilde von Reaktionsbeginn an wurde mit Hilfe eines einfachen Modells auf Basis der stochastischen Methode beschrieben. Die Verankerung eines Palladium-Kolloids in dem Partikelnetzwerk führte zu einem katalytisch aktiven Material.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052500105
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    Two-component diacrylate networks from liquid-crystalline and non-liquid-crystalline monomers I. Synthesis of the monomers, phase behaviour of the binary monomer mixtures, network formation (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 250 (1997), S. 105-117 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aus Bisacrylaten wurden durch photoinduzierte Vernetzung in der isotropen Phase zweikomponentige Netzwerke synthetisiert. Bei allen Systemen wurde als eine Komponente ein Bisacrylat verwendet, das eine flüssigkristalline Phase bilden kann, und als zweite Komponente ein Bisacrylat, das dazu nicht in der Lage ist. Die isotrope Komponente wurde hinsichtlich ihrer Größe, Geometrie und Polarität variiert. Für alle Systeme wurden mittels einer Wärmeflußkalorimetrie (DSC) Phasendiagramme der Monomermischungen erstellt. Das Phasenverhalten der Systeme zeigt eine Abhängigkeit vom Schmelzpunkt und der chemischen Struktur der isotropen Zweitkomponente. Die Vernetzungstemperatur wurde so gewählt, dafß die Vernetzung in der isotropen Phase 10 °C über der Phasenllbergangstemperatur erfolgte. Die Reaktionskinetik wurde aus den Photopolymerisationsenthalpien mittels eines für photochemische Vernetzungen modifizierten DSC-Gerätes untersucht. Die Zeitabhängigkeit des Umsatzes und der Gesamtumsatz an Acrylatbindungen wurden aus den DSC-Kurven ermittelt. Der Gesamtumsatz hängt nicht von der Reaktionstemperatur und der Struktur der Monomeren ab und liegt je nach Zusammensetzung füralle Systeme zwischen 53 und 71%. Die Zeitabhängigkeit des Umsatzes hingegen wird von der Struktur des nicht flüssigkristallinen Comonomeren beeinflufßt.
    Notes: Two-component networks of diacrylate monomers were synthesized by photoinduced polymerization in the isotropic phase. In all systems one component was a liquid-crystalline diacrylate, whereas the second component was a non-liquid-crystalline diacrylate, which was varied in size, geometry and polarity. The phase behaviour of the monomer mixtures has been analysed by differential scanning calorimetry (DSC). It is influenced by the melting point and the structure of the non-liquid-crystalline component. All samples were cross-linked in the isotropic phase 10°C above the phase transition temperature and a modified differential scanning calorimeter was used to investigate the enthalpies of photopolymerization. The final value and the time dependence of the conversion of acrylate double bonds were calculated from the DSC curves. The final degree of conversion of the acrylate double bonds was between 53 and 71% for all samples, whereas no significant dependence of the degree of conversion on the chemical structure of the monomers or the reaction temperature has been found. In contrast, the time dependence of the conversion was influenced by the chemical structure of the non-liquid-crystalline component.
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    Synthèse d'une résine antistatique par introduction de sites ioniques dans le système Epikote 1001®-Euredur 423® (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 253 (1997), S. 111-130 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: This work is an attempt to provide antistatic properties to a commercial epoxy resin made up with Epikote 1001® and Euredur 423®. In this aim, two compounds were selected which could be chemically bonded to the resin network: (2,3-epoxypropyl)-trimethylammonium chloride which contains an epoxy group and the ammonium chloride group for the antistatic properties and also tetrabutylammonium 2-aminoethanesulfonate which contains an amino group and the tetrabutylammonium sulfonate group. Different formulations of the resin were prepared with both compounds, their viscosity and their resistivity were measured. Antistatic properties were obtained with the highest contents of epoxy compound. On the contrary no antistatic properties could be observed with the amino compound. Hardness and adherence tests have given suitable results for the antistatic formulations.
    Notes: Le but de cette étude est d'apporter des propriétés antistatiques durables à la résine époxy obtenue à partir d'Epikote 1001® et d'Euredur 423®. Deux composés pouvant se lier chimiquement à la résine ont été choisis: le chlorure de (2,3-époxypropyl)triméthylammonium qui contient un groupe époxy comme l'Epikote 1001® et un groupement chlorure d'ammonium pour les propriétés antistatiques et le 2-aminoéthanesulfonate de tétrabutylammonium qui contient un groupement amine comme l'Euredur 423® et le groupement sulfonate. Différentes formulations de la résine ont été préparées avec ces deux composés. Leur viscosité et leur résistivité ont été mesurées. Des propriétés antistatiques ont été observées avec des échantillons à taux élevé de composé époxyde. Par contre, le composé à groupement amine n'a montré aucune propriété antistatique. Des tests de dureté et d'adhérence se sont révèlés intéressants pour les formulations présentant des propriétés antistatiques.
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    Compared properties of aromatic polyamides containing silicon in the main chain (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 253 (1997), S. 169-182 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Zwei Reihen aromatischer Polyamide mit Silicium und Phenylchinoxalin- oder Hexafluorisopropyliden-Gruppen wurden hergestellt und ihre Eigenschaften mit denen verwandter Polymerer verglichen. Die Polymeren sind leicht löslich in polaren amidischen Lösungsmitteln wie N-Methyl-2-pyrrolidinon und Dimethylformamid sowie in Tetrahydrofuran. Aus diesen Lösungen können dünne, transparente Filme gegossen werden. Die gewichts- und zahlenmittleren Molekulargewichte der Polyamide liegen im Bereich 10000-40000 bzw. 3000-6000, die Uneinheitlichkeiten im Bereich 3-10. Die Glasübergangstemperaturen liegen zwischen 236°C und 275°C, die Zersetzungstemperaturen oberhalb von 400°C. Die Dielektrizitätskonstanten der Polymerfilme sind niedrig (3.26-3.68), die mechanischen Eigenschaften gut (Zugfestigkeit 74-100 MPa, Zugmodul 180-386 MPa) und mit denen anderer „high performance“-Dielektrika vergleichbar.
    Notes: Two series of aromatic polyamides incorporating silicon together with phenylquinoxaline or with hexafluoroisopropylidene groups have been synthesized and their properties have been characterized and compared with those of related polymers. These polymers are easily soluble in polar amidic solvents such as N-methyl-2-pyrrolidinone and dimethylformamide, and in tetrahydrofuran, and can be cast into thin, transparent films from solution. The polyamides have weight- and number-average molecular weights in the range of 10 000-40 000 and 3 000-6 000, respectively, and polydispersities in the range of 3-10. They show glass transition temperatures in the range of 236°C-275°C and decomposition temperatures above 400°C. The polymer films have low dielectric constants in the range of 3.26-3.68, and good mechanical properties (tensile strength 74-100 MPa, tensile modulus 180-386 MPa), thus being comparable with other high performance dielectrics.
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    Biological degradation of cellulose acetate films: Effect of plasticizer (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 253 (1997), S. 193-200 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Bioabbau von weichgemachtem Celluloseacetat (PCA) wurde durch Kompostierung mit einem standardisierten kommunalen Feststoffabfall (ED 73) untersucht. Der relative prozentuale Gewichtsverlust der Proben wurde gemessen und der aerobe Bioabbau in einem kontrollierten aeroben Kompostiersystem ermittelt, mit dem das durch den mikrobiologischen Metabolismus gebildete CO2 aufgefangen wurde. Infrarotspektren (FTIR), mechanische Eigenschaften und Molekulargewicht zersetzter PCA-Filme zeigen, daß die Fraktionen mit niedrigerem Molekulargewicht (wie z.B. Weichmacher und niedriger substituierte Fraktionen von PCA) bevorzugt abgebaut und aus dem PCA entfernt werden.
    Notes: Biodegradation of plasticized cellulose acetate (PCA) was established with a standard municipal solid waste (ED 73). The relative percent weight loss of the specimen was measured, and the aerobic biodegradation was evaluated in a controlled aerobic composting system that was designed to capture CO2 produced by microbiological metabolism. Infrared spectra (FTIR), mechanical properties and molecular weight of degraded PCA films indicate that the lower molecular weight fractions, such as plasticizer and lower substituted fractions of PCA, are biodegraded and removed preferentially from the PCA.
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    NON-COVALENT INTERACTIONS IN HOST-GUEST COMPLEXES WITH FLUORINATED PHENYL COMPOUNDS (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 305-310 
    Details
    ISSN: 0894-3230
    Keywords: non-covalent interactions ; host-guest complexes ; fluorinated phenyl compounds ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Complexation constants with the macrocyclic azoniacyclophane CP44 and phenyl guest compounds with at least four fluorine atoms or alternatively protons at the ring were obtained by NMR shift titrations in water. The fluorinated compounds show free energies of complexation which are smaller by ΔΔG=3·4-7·7 kJ mol-1 in comparison with the protonated compounds. The NMR shifts induced upon 100% complexation (CIS values) were obtained simultaneously from non-linear least-squares fitting and indicate intra-cavity inclusion in all cases. The CIS values agree roughly with screening constants calculated from aromatic ring current and linear electric field effects, the latter resulting from the permanent charges at the host compound. Molecular mechanics calculations (CHARMm) indicate that intracavity inclusion is possible with all compounds with negligible strain induced (〈1 kJ mol-1) in the macrocycle upon complexation. In contrast, α-cyclodextrin can accommodate fluorinated phenyl compounds only at the rim of the cavity without larger strain. Preliminary data with α-cyclodextrin, obtained by competitive UV-visible titration with methyl orange, indicate again a smaller association free energy (ΔΔG=1·-7 kJ mol-1) for pentafluorphenol compared with normal phenol as guest. © 1997 John Wiley & Sons, Ltd.
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    CHARACTERIZATION OF THREE-DIMENSIONALLY EXTENDED HYDROPHOBIC CAVITIES. DIFFERENCE IN MOLECULAR RECOGNITION ABILITY BETWEEN STEROID AND OCTOPUS CYCLOPHANES (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 351-357 
    Details
    ISSN: 0894-3230
    Keywords: hydrophobic cavity characterization ; cyclophanes ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The guest-binding behavior of two different cyclophane hosts, each being capable of providing a three-dimensionally extended hydrophobic cavity toward aromatic guests, was examined in aqueous media: a steroid cyclophane bearing four rigid cholate moieties and an octopus cyclophane having four flexible double-chain segments. Even though the binding constant for 2,7-dihydroxynaphthalene with the steroid cyclophane was comparable to that with the octopus cyclophane, the guest binding modes were very different from each other, as confirmed by 1H NMR spectroscopy. That is, the steroid cyclophane incorporates the guest into its rigid macrocyclic cavity with axial geometry whereas the octopus cyclophane provides a three-dimensional space created by the macrocyclic skeleton and the flexible hydrocarbon chains so that the long axis of the guest becomes more or less perpendicular to the molecular axis of the host upon complexation. Temperature-dependent molecular recognition by these hosts toward 8-anilinonaphthalene-1-sulfonate was examined by means of fluorescence spectroscopy. Characteristic differences in the guest-binding mode between these hosts were sensitively reflected in the thermodynamic entropy change on host-guest complexation and the temperature-dependent microscopic viscosity experienced by the guest at the binding site. © 1997 John Wiley & Sons, Ltd.
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    π-π INTERACTIONS IN SELF-ASSEMBLY (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 254-272 
    Details
    ISSN: 0894-3230
    Keywords: π-π interactions ; self-assembly ; catenanes ; cyclophanes ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The recent surge of interest in the control of molecular organization in both the solution state (i.e. self-assembly) and the solid state (i.e. crystal engineering) has led researchers to recognize increasingly the importance of weak non-covalent interactions. The design and synthesis of an efficient molecular construction set are dependent upon a very close interplay between x-ray crystallography and synthetic chemistry. π-π Stacking interactions between π-donors, such as hydroquinone, resorcinol or dioxynaphthalene residues, and π-accepting ring systems, such as bipyridinium or π-extended viologen units, can govern the self-assembly of a variety of complexes and interlocked molecular compounds in both the solid and solution states. Non-covalent bonding interactions (i.e. π-π interactions) can be considered as information vectors: they define and rule the self-assembly processes that lead to the formation of the desired molecular and supramolecular architectures, and thereafter they still govern the dynamic processes occurring within the self-assembled structures and superstructures. The manner in which such molecules and supermolecules can contribute to an understanding of non-covalent interactions at both structural and superstructural levels is described, with reference to numerous examples of self-assembly processes in synthesis, of dynamic processes in the solution state, and of the packing of molecules and molecular complexes in the solid state. © 1997 John Wiley & Sons, Ltd.
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    REDOX-SWITCHED AMPHIPHILES: OXIDIZED FERROCENE DERIVATIVES FORM STABLE VESICLES WHEN EITHER ONE OR TWO ALKYL TAILS ARE PRESENT (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 323-334 
    Details
    ISSN: 0894-3230
    Keywords: redox-switched amphiphiles ; ferrocene derivatives ; vesicles ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: ---Thirty ferrocene derivatives were prepared and their ability to form vesicles in aqueous solution when oxidized was assessed. The compounds included alkyl ferrocenylmethyl ether derivatives of the form C10H9FeCH2OR in which R=octyl, dodecyl, tetradecyl, hexadecyl, octadecyl and eicosanyl. One single-tailed amine derivative, C10H9FeCH2NR2, R=octadecyl, was studied. Alkylferrocene derivatives had the form C10H9FeR in which R=butyl, decyl, tetradecyl, hexadecyl, octadecyl, eicosanyl and docosanyl. Sixteen symmetrical 1,1′-disubstituted ferrocenes were also studied. Three ethers were of the form C10H8Fe-1,1′-(CH2OR),2, R=tetradecyl, hexadecyl and octadecyl. Four corresponding dialkyl derivatives of the form C10H8Fe-1,1′-R2, R=decyl, tetradecyl, hexadecyl and octadecyl, were assessed. Finally, a range of 1,1′-disubstituted ferrocene derivatives were analyzed. These all had the form C10H8Fe-1,1′-(COR)2, for which R has the following identities: octyl, tridecyl, pentadecyl and heptadecyl (ketones); heptadecyloxy, 3-cholesteryl and 3-cholestanyl (esters); and two amides, R=NHC18H37 and N(C18H37)2. The alkyl and ether derivatives could be readily oxidized and formed vesicular aggregates upon sonication. The ketones, esters and amides could be oxidized but the ferricenium derivatives did not form stable aggregates. An interesting observation is that the aggregates formed were vesicular whether the ferrocene derivative had one or two alkyl tails. © 1997 John Wiley & Sons, Ltd.
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    CATION-π INTERACTIONS IN CALIX[n]ARENE AND RELATED SYSTEMS (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 273-285 
    Details
    ISSN: 0894-3230
    Keywords: cation-π interactions ; calix[n]arenes ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Non-covalent intermolecular forces have been recognized as a very important part of molecular interactions in complex biological systems. The fundamental functions of living matter such as transcription of genetic information in DNA, spatial arrangement of protein molecules, enzymatic functions or immunity system response are enabled owing to the presence of weak non-covalent forces based on hydrogen bonding interactions, van der Waals interactions, electrostatic interactions, hydrophobic effects, etc. Recently, among them so-called "cation-π" interactions have been proved to contribute to the overall binding process in various artificial or biological systems. Calix[n]arenes have emerged as an important family of molecules with promising applications in many branches of chemistry. Because of their suitable molecular preorganization with aromatic units being "concentrated' in a relatively small space, calix[n]arenes represent interesting compounds exhibiting an enhanced ability for cation-π interactions. The importance of such forces in calix[n]arene chemistry is demonstrated here on several recent examples. © 1997 John Wiley & Sons, Ltd.
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    HYDROPHOBIC INTERACTIONS IN AQUEOUS SOLUTIONS: THEIR OPERATION IN LIVING SYSTEMS (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 335-342 
    Details
    ISSN: 0894-3230
    Keywords: hydrophobic interactions ; aqueous solutions ; living systems ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: ---Evidence is provided for the enormous role of hydrophobic interactions in aqueous solutions. It is concluded that complementary functions of hydrophilic and of hydrophobic species are in continuous operation and that these are a conditio sine qua non for the existence of the liquid. With regard to the supermolecular aggregations, hydrophobic interactions are operative on the highest hierarchic levels of the system organization, i.e. at the interface and at the holes around dissolved hydrophobic species. It is further emphasized that water is essential both for the unity and for the differentiation of each living organism. With regard to its role for the differentiation of the body, the hydrophobic interactions are of paramount importance, notably those provided by amphipathic solutes. The cell membrane is considered to be the result of interactions between the highest hierarchic levels of intracellular and extracellular water. The hydrophobic double layer provides the barriers for the separation of intracellular and extracellular water and at the same time the connections for recognition and for exchange of information between them. The DNA structures obtain conservative boundary conditions for their surrounding water systems which do not freeze at -60 °C. These water systems are dynamically superior to all other parts of the water system of the organism. It is suggested that more knowledge about the abilities of liquid water can be obtained by giving appropriate attention to its properties within the living body. © 1997 John Wiley & Sons, Ltd.
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    INTRINSIC (GAS-PHASE) BASICITIES AND STABILITY OFCHARGE-TRANSFER COMPLEXES IN SOLUTION (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 343-346 
    Details
    ISSN: 0894-3230
    Keywords: charge-transfer complexes ; intrinsic (gas-phase) basicities ; stability ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: ---The standard Gibbs energy changes for the formation of 1:1 charge-transfer complexes between molecular iodine and several bases in solution at 25·0 °C [ΔG0l2(soln)] were determined experimentally. The bases were 2,2,2-trifluoro- ethylamine, cyclopropylamine and 1,1,3,3-tetramethylguanidine. These [ΔG0l2(soln)] values, determined in n-heptane, and also that for the formation of the 1:1 complex between 2,2,2-trifluoroethanethiol and molecular iodine in dichloromethane, were found to follow with excellent precision the correlation equations linking ΔG0l2(soln) and the intrinsic (gas-phase) basicities of N(sp3), N(sp2) and S(sp3) bases. These findings strongly support previous conclusions regarding the relationship between gas-phase and solution reactivity data. © 1997 John Wiley & Sons, Ltd.
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    NON-AQUEOUS TITRATIONS AS A TOOL IN THE STUDY OF MOLECULAR RECOGNITION PHENOMENA. USES IN DISTINGUISHING HYDROGEN BONDING FROM PROTON TRANSFER, THE MEASUREMENT OF COMPLEX INDUCED pKa SHIFTS, AND THE ABILITY TO DISTINGUISH THE CATALYTIC ROLES OF GENERAL ACIDS AND BASES (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 396-404 
    Details
    ISSN: 0894-3230
    Keywords: molecular recognition ; non-aqueous titration ; hydrogen bonding ; proton transfer ; pKa shifts ; acid-base catalysis ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Whenever hydrogen bonding is involved in molecular recognition, the possibility of a proton transfer from the donor to the acceptor arises. In most cases the pKa of the donor is far enough above the pKa of the conjugate acid of the acceptor for it to be clear that no proton transfer will occur. However, as the difference between the donor and acceptor pKas decreases, it can become difficult to predict whether a proton transfer will occur. Since most hydrogen bond-driven molecular recognition is studied in low dielectric solvents, non-aqueous titrations can be used to measure the pKas and therefore predict proton transfers. In this paper three studies which involved non-aqueous titrations are summarized. The first deals with distinguishing simple proton transfer from host-guest complex formation. The second involves measuring pKa shifts upon host-guest complex formation. The last is a study of the catalysis of a phosphoryl transfer. In all three scenarios the non-aqueous titration method gave results which would have been difficult to obtain by other means, and which proved crucial for a complete understanding of the molecular recognition process. © 1997 John Wiley & Sons, Ltd.
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    THEORETICAL STUDIES OF THE SUPRAMOLECULAR SYNTHON BENZENE · · · HEXAFLUOROBENZENE (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 347-350 
    Details
    ISSN: 0894-3230
    Keywords: benzene · · · hexafluorobenzene ; supramolecular synthon ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The benzene · · · hexafluorobenzene stacking interaction was evaluated at several levels of theory. At the MP2/6-31G** level, it is estimated that the interaction is stabilizing by approximately 3.7 kcal mol-1. Lower levels of theory perform poorly on this system. This is a fairly strong non-covalent interaction, suggesting this motif may be a valuable supramolecular synthon. © 1997 John Wiley & Sons, Ltd.
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    HYDROGEN BONDING. 42. CHARACTERIZATION OF REVERSED-PHASE HIGH-PERFORMANCE LIQUID CHROMATOGRAPHIC C18 STATIONARY PHASES (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 358-368 
    Details
    ISSN: 0894-3230
    Keywords: hydrogen bonding ; RP-HPLC C18 stationary phases ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The linear free energy equationlogk′ = c + rR2 + sπ2H + a∑α2H + b∑β2 + vVxwas applied to the capacity factors for various sets of solutes on C18 stationary phases with aqueous methanol and acetonitrile eluents. Here, k′ are the capacity factors for a series of solutes with a given C18 phase and a given eluent, and R2, π2H, ∑α2H, ∑β2, Vx are parameters or descriptors of the solutes as follows: R2 is an excess molar refraction, π2H is the solute polarizability/dipolarity, ∑α2H and ∑β2 are the solute hydrogen-bond acidity and basicity and Vx is the solute volume. It is shown that although the regression coefficients r, s, a, b and v vary widely within the C18 column and mobile phase used, the ratios r/v, s/v, a/v and b/v are remarkably constant. Thus, for the retention of 25 series of solutes on six different C18 columns with 30-90% aqueous methanol as the eluent, all the 25 LFER equations can be combined into one general equation:logk′ = c + v(0.13 R2 - 0.32 π2H - 0.22 ∑α2H - 0.90 ∑β2O + 1.00 Vx)where only c and v vary from system to system. For 11 other phases for which data are available, the ratios v/A and (v + c)/A are constant, where A is the quantity of stationary phase per unit surface area. Similar results were found with C18 phases and aqueous acetonitrile as eluents. Although a first examination of equations based on the first equation above suggests that various C18 phases behave differently, for example the v coefficient, that is related to the observed hydrophobicity of a stationary phase relative to the mobile phase, varies considerably from phase to phase with the same eluent, a detailed analysis led to the conclusion that all the C18 phases examined have roughly the same hydrophobicity, when the v coefficients are corrected for the quantity of stationary phase per unit surface area. It is suggested that these corrected v coefficients, v/A and (v + c)/A, can be regarded as the ‘intrinsic’ phase hydrophobicity. © 1997 John Wiley & Sons, Ltd.
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    MECHANISMS FOR CHIRAL RECOGNITION BY CYCLODEXTRINS (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 286-291 
    Details
    ISSN: 0894-3230
    Keywords: chiral recognition ; cyclodextrins ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: ---The mechanisms for chiral recognition by cyclodextrins (CDxs) are discussed. Examples of host-guest systems where the "lock-and-key mechanism" and the "three-point rule" are applicable are cited and discussed. Most results reported so far suggest that the ability of native CDxs and chemically modified CDxs to discriminate between enantiomers of guests having a central chirality is low in aqueous solutions. Small ΔΔG values for enantioselective complexation of CDxs with amino acids seem to be due to unpredictably small changes in the structures of the complexes of the guest enantiomers. Therefore, it is very difficult to prove the participation of hydrogen bonding in chiral recognition through the "three-point rule" in these systems. The use of the Coulomb interaction and the coordinate bonds as point interactions is discussed. CDxs might be good hosts to recognize axial chirality or helicity of guests. Hydrogen bonding in water is assumed in the recognition of the helicity of bilirubin. Very large ΔΔG values have been reported for the chiral recognition of the binaphthyl derivatives. Such a system seems to be a suitable model system to study the mechanism of chiral recognition by CDxs. © 1997 John Wiley & Sons, Ltd.
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    REACTION OF ARYLIMODIMAGNESIUM WITH AROMATIC BIFUNCTIONAL NITRILES: COMPETITION AND/OR COOPERATION OF FUNCTIONAL GROUPS AFFECTED BY ELECTRON-ACCEPTING ABILITY AND LOCATION (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 242-252 
    Details
    ISSN: 0894-3230
    Keywords: aryliminodimagnesium ; condensation with NO2 and CO groups ; addition to CN group ; single electron transfer efficiency ; σ-complexation ability ; inter- and intramolecular competition ; bifunctional substrates ; positional effect of functional groups ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: ---The reactions of aryliminodimagnesium [ArN(MgBr)2, IDMg] with p′-substituted p-cyanobenzophenones, 1-cyano-9-fluorenone, o-, m- and p-dicyanobenzenes and o-, m- and p-nitrobenzonitriles were examined, and the relative yields of products were referred to the previous results of electron spin resonance studies. The products of condensation with carbonyl and nitro groups and of addition to cyano groups were formed. From the variations of the yields caused by the molar ratio of the magnesium reagent versus substrates and by the substituents of both reactants, the preferred groups were determined. The groups of p- and m-substrates are consistent with the position of highest density of free electrons in the anion radicals, whereas those of the o-substrates are inconsistent. The consistency indicates competition of functional groups reflecting the relative ability of single electron acceptance from the reagent, whereas the inconsistency is ascribed to cooperation of neighbouring groups for σ-complexation with the Mg atom of the reagent. The categories of competition and cooperation are discussed in relation to fundamental features and general governing factors proposed for the IDMg reactions of monofunctional substrates. © 1997 John Wiley & Sons, Ltd.
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    INFLUENCE OF ISOTOPIC SUBSTITUTION ON STRENGTH OF HYDROGEN BONDS OF COMMON ORGANIC GROUPS (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 383-395 
    Details
    ISSN: 0894-3230
    Keywords: hydrogen bond strength ; organic groups ; isotopic substitution ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Although the electronic contribution to the strength of a H-bond is unaffected by isotopic substitution, the heavier mass of deuterium compared with protium lowers some of the vibrational frequencies in the complex. The binding energy of the complex, which includes zero-point and thermal vibrational energies, can thus be altered by several tenths of a kcal mol-1 by H/D substitution. Ab initio calculations are used to analyze this phenomenon in a number of common organic functional groups that are prone to form H-bonds: hydroxyl, carboxyl and amide, both self-complexing as homodimers and with water molecules as partners. It is found that any site of D-substitution increases the complexation energy; however, the bridging sites show a stronger preference for D over H than do the non-bridging, or terminal, sites. Hence D-bonding can be considered to be stronger than H-bonding in these functional groups. Of the groups considered, the energetic preference for D over H is greater in the hydroxyl group, so deuterium would be expected to gravitate toward solvent water molecules in isotopic scrambling experiments. The increments in H-bonding energy resulting from each site of substitution are addititve in cases of multiple substitution. © 1997 John Wiley & Sons, Ltd.
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  • 95
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    EDITORIAL: NON-COVALENT INTERACTIONS (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 253-253 
    Details
    ISSN: 0894-3230
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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    QUANTIFICATION OF NON-COVALENT INTERACTIONS ON THE BASIS OF THE THERMODYNAMIC HYDROGEN BOND PARAMETERS (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 405-413 
    Details
    ISSN: 0894-3230
    Keywords: non-covalent interactions ; thermodynamic hydrogen bond parameter ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: ---This paper describes how empirical free energy and/or enthalpy values for hydrogen binding strength are derived from thousands of corresponding measurements between H-bond donors and acceptors, mostly in carbon tetrachloride, and how they can be used to construct common scales or factor values (increments) also for other reactions involving electron donor and acceptor ability of functions. The corresponding databases and programs (HYBOT) allow one to predict thermodynamic values for experimentally unknown equilibria, including also ionophore complexes with crown ethers or cryptands. Applications in QSAR involve the prediction of lipophilicity from any structure on the basis of only two variables, e.g. 234 systems are described this way with a correlation coefficient r=0·96. Similarly, permeabilities and some biological properties such as narcotic activities of chemicals and anti-HIV-1 activity of some porphyrins are evaluated. © 1997 John Wiley & Sons, Ltd.
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    INCLUSION COMPLEXATION OF CYCLOBIS(PARAQUAT-p-PHENYLENE) AND RELATED CYCLOPHANE DERIVATIVES WITH SUBSTITUTED AROMATICS: COOPERATIVE NON-COVALENT CAVITY AND EXTERNAL INTERACTIONS (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 369-382 
    Details
    ISSN: 0894-3230
    Keywords: inclusion complexation ; cyclobis (paraquat-p-phenylene) ; cyclophanes ; substituted aromatics ; cooperative non-covalent cavity ; external interactions ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: ---The cooperative nature of non-covalent interactions which give rise to inclusion complexes involving cyclobis(paraquat-p-phenylene), 14+, and related cyclophane derivatives, 24+-44+, with substituted 1,4-phenyl and 4,4′-biphenyl guests has been studied by spectroscopic techniques and ab initio and semiempirical molecular orbital methods. Inclusion complex formation and stability are primarily determined by the combination of two main interaction modes involving aromatic stacking of the guest within the cyclophane cavity and external interactions between guest side arms and the exterior of the cyclophane. A balance between cavity and external forces results in supramolecular association and is shown to change depending upon the functionality and substitution of the guest. Cavity binding was probed using 1,4-phenyl and 4,4′-biphenyl guests, where for the 1,4-phenyl guests the primary basis for energy stabilization with 14+ is found to be short-range stabilizing electrostatic forces complemented by small amounts of polarizability and charge-transfer. In contrast, the cavity binding between substituted 4,4′-biphenyl guests and 14+ is determined by almost equal contributions of polarizability and electrostatics. The effect of solvent is shown to have only a small effect on the computed geometry of 14+ complexes, but its impact upon binding energies is substantial. The first solvation shell of the cyclophanes is computationally approximated by 12 acetonitriles and satisfies the requirements of the 16 relatively acidic protons on the bipyridinium groups. Good correlations between the computed (with solv ation) and experimental 14+ binding energies are found. The degree of linear correlation improves substantially when the comparison between computed and experimentally observed binding energies is restricted to structurally similar (number of aromatic rings, number of substituents and position of substitution) molecular guests. Furthermore, computed molecular properties, such as polarizability, maximum hardness, softness and electronegativity of the isolated guests, correlate well with 14+ binding energies based upon the same requirement of guest similarity. The non-covalent forces associated with the external cyclophane interactions were studied with guest molecules built from symmetrical 1,4-extensions of hydroquinone composed of aliphatic or ethyleneoxy side arms. In particular, side arm length and functionality, and the position and type of heteroatoms along the chain, were systematically varied to define the external interactions between the guest side arms and different host cyclophanes. Specifically, the ethyleneoxy linkages are shown to provide a large chelate and cooperative effect which direct the binding with 14+. In order to probe further the special geometric and electronic character of 14+, we have synthesized and tested a new supramolecular host, 24+, similar to 14+ but where a pentacycloundecane unit replaces one of the xylyl groups. Both experimental and computed data on the new host emphasize the ideal geometry and electronic nature of the 14+ molecular receptor for aromatic guests. The inclusion complexes discussed in this paper are important not only because they, or similar entities, are the main components of many rotaxanes, catenanes and other switchable molecules, but because the intermolecular interactions involved, such as electrostatics, polarizability and charge-transfer, are ubiquitous in supramolecular chemistry. The information reported on the specific interactions involving the 14+-44+ molecular receptors with substituted aromatic guests can also be extended by analogy to many systems of broad interest. © 1997 John Wiley & Sons, Ltd.
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  • 98
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    REACTIONS OF LITHIUM WITH BENZALDEHYDE IN SOLUTION (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 233-241 
    Details
    ISSN: 0894-3230
    Keywords: surface effects ; radical anions ; benzoyl radical ; coupling of radicals ; surface catalysis ; electron transfer ; reactions in the double laye ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Benzaldehyde in THF reacts with lithium metal to give the expected reduction product, benzyl alcohol, plus benzoin and benzyl as minor products. The kinetics of the overall reaction as well as the partial rate coefficients of the several steps have been determined under various reaction conditions. It was found that adsorption on the surface and electron transfer from the lithium to benzaldehyde are the slow steps. The experimental results show interesting surface effects, and evidence for significant radical intermediates, which were characterized by their epr spectra and trapping experiments, results useful to gain insight into the mechanisms of these and other related reactions. © 1997 John Wiley & Sons, Ltd.
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    MOLECULAR DYNAMICS STUDY OF THE COMPLEXATION OF LUMINESCENT CATIONS BY ENCAPSULATING LIGANDS WITH BIPYRIDINE UNITS (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 292-304 
    Details
    ISSN: 0894-3230
    Keywords: calixarenes ; bipyridine ; lanthanides ; luminescence ; preorganization ; solvent effect ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: ---Based on MD simulations, the structures of Eu3+ and EuCl3 complexes of bipyridine-substituted calixarenes in different environments (in vacuo and in acetonitrile and water solutions) were modelled. The data account for the differences in their luminescence properties. The role of the calixarene platform, preorganization of the ligands, and an explicit account of counterions in different environments are analysed. © 1997 John Wiley & Sons, Ltd.
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  • 100
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    ENANTIOSELECTIVE BINDING IN GAS CHROMATOGRAPHY:A COMPUTATIONAL STUDY OF CHIRAL SELECTION BYPERMETHYL-β-CYCLODEXTRIN (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 311-322 
    Details
    ISSN: 0894-3230
    Keywords: enantioselective binding ; gas chromatography ; chiral selection ; permethyl-β-cyclodextrin ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: ---Stochastic molecular dynamics simulations were used to determine the enantiomer retention orders of moderately polar analytes binding to permethylated β-cyclodextrin, a popular chiral stationary phase used in gas chromatography. It is found that averaging over multiple trajectories, each of which are lengthy, is required to faithfully reproduce experiment. From the simulations we find the major binding domain to be the interior of the macrocycle rather than the exterior with most analytes having a preference for associating to the primary rim rather than to the secondary rim. It is also found that the intermolecular forces responsible for holding the complexes together are the short range dispersion forces, and that the enantiodifferentiating forces of the competing diastereomeric complexes are dominated by the van der Waals contributions to the intermolecular energy. © 1997 John Wiley & Sons, Ltd.
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