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  • Polymer and Materials Science  (6,639)
  • 1995-1999  (3,277)
  • 1965-1969  (3,362)
  • 1997  (3,277)
  • 1968  (1,720)
  • 1967  (1,642)
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  • 1995-1999  (3,277)
  • 1965-1969  (3,362)
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  • 1
    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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  • 2
    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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  • 3
    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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  • 4
    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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  • 5
    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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  • 6
    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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  • 7
    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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  • 8
    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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  • 9
    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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  • 10
    Electronic Resource
    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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  • 11
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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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  • 12
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    Electronic Resource
    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 
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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: 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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    URL: http://dx.doi.org/10.1002/apmc.1997.052510106
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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%.
    Additional Material: 8 Ill.
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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.
    Additional Material: 6 Ill.
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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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    URL: http://dx.doi.org/10.1002/apmc.1997.052510107
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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 
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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: No Abstract
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    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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    URL: http://dx.doi.org/10.1002/apmc.1997.052520110
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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 
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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 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 
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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: 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.
    Additional Material: 4 Tab.
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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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    Optical rotatory dispersion of E. coli ribosomes and their constituents (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 1-4 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigations have been made on the optical rotatory dispersion properties of E. coli ribosomes and their constituent RNA and proteins. The results indicate that (1) no conformational changes are involved in the formation of a 70S particle from the 50S and 308 subunits, (2) the E. coli ribosomal proteins are similar to most globular proteins with little α-helix content, and (3) the conformation of RNA and proteins inside the ribosome is very similar to that in the free state.
    Additional Material: 1 Ill.
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    Molecular configuration of amylose and its complexes in aqueous solutions. Part II. Relation between the DP of helical segments of the amylose-iodine complex and the equilibrium concentration of free iodine (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 5-16 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The iodine which is added to an aqueous amylose solution is bound only partly by the amylose while forming the blue complex and partly remains free. The equilibrium normality of the free and the bound iodine at half-saturation of amylose by iodine is designated as [If]v and [Ib]w, respectively. The stability of the poly iodine chain formed within the axis of amylose helices depends on its length, i.e., indirectly on the DP of the amylose helices: the greater this stability, the lower the [If]v value. The amylose molecule consists of helical segments. Such a molecule may behave as a random coil. The average length of the helical segments in freshly prepared amylose-iodine complexes depends on temperature, pH, iodide concentration, the presence of other complex-forming agents, and the DP of the amylose. This latter factor is investigated in the present paper. By the aid of an automatically recording photometrictitrating device the coherent values of [Ib] and [If] were determined. Plotting these values against DPn for mechanochemically degraded as well as for periodateo-xidized amyloses resulted in curves consisting of two linear sections. The break of the curves occurred between DPn 110 and 130. It was concluded that below DPn = 100 the DP of helical segments (= sDPn) is identical to the DPn of the total molecule, i.e., the molecule consists of only a single, relatively stiff helix. Above this limit the molecule contains several helical segments. The DP of these helical segments can be calculated as follows: sDPn = 141.1 - 10.2 × 105[If]v. This equation is considered to be valid for 0.5-0.6 mg. amylose in 100 ml. 0.1N HCl at 20°C., λ = 650 mμ, euuvet diameter 3.4 cm., the feed rate of the iodate-iodide titrating solution (in acid medium resulting in a 5 × 10-3N I2 solution with a molar iodide to iodine ratio of 1.5) is 0.4ml./min. Amylose molecules of, e.g., DPn = 1380 consist of an average of 11.4 segments having a DP of about 120 and consisting of an average of 15-18 helical turns.
    Additional Material: 6 Ill.
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    Wechselstrompolarographische kriterien der nucleinsäuredenaturierung (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 61-68 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electrochemical possibilities for investigation of nucleic acids with high molecular weight are restricted to the determination of the adsorption behavior. According to our experience the alternating current polarography (Breyer-polarography) is mainly appropriate for the characterization of changes in the secondary structure of DNA. The Breyer-polarogram shows the alternating current of the dropping electrode in dependence on their potential which varied from 0-2 v. negative against the normal calomel electrode (NCE). By addition of native DNA to the supporting electrolyte (buffer solution) the current drops down in the range of adsorption between 0 and 1 v. At 1.16 v. against NCE the desorption takes place together with the formation of a rounded desorption peak. The investigation was carried out in phosphate buffer solution 0.1m with 0.075m NaCl or in a phosphate buffer 0.18m with 0.03m NaCl. In the pH range above pH 8 NaOH was added to realize the higher pH values. A calf thymus DNA sample having a mean molecular weight of about 18 million was used. The concentration of DNA was 5 × 10-3-1 × 10-1 wt.-%. The polarographic measurements were performed with an a.c./d.c.-polarograph “GWP 564” from Akademiewerkstätten für Forschungsbedarf der Deutschen Akademie der Wissenschaften zu Berlin (DAW). The denaturation of the double helix causes a sharp desorption peak at negative potentials of the alternating current polarogram. This new criterion for the helix-coil transition is due to formation of unpaired bases. These nearly free bases undergo a specific adsorption and the desorption takes place within a narrow potential range. Nevertheless, at present time an electron transfer to particular bases cannot be excluded at special conditions. The increase of the sharp peak permits to estimate: (a) the melting curve of the double helix in agreement with spectroscopic measurements; (b) the photolysis of the double helix; (c) the strand separation in acid and alkaline solution. In the alkaline range the sharp peak increases and reaches its maximum at pH 〉 12. In the acid range, however, no sharp peak is observed and the rounded desorption peak decreases. Therefore, the best way of following the conformation changes is to measure the current difference between the curves of the solutions with and without DNA at electrocapillary-zero-potential. On the classical d.c.-polarogram one can measure small current steps only, which may be caused mainly by capacity changes. Moreover, the scission of the molecule by ultrasonic action can be followed. In this case the rounded peak of DNA increases but the sharp peak does not appear. Similar alternating current polarograms are obtained with poly-A in the native state, because helical and unordered regions coexist in the same molecule. The very rapid indication of these structure changes allows one to carry out kinetic measurements at a fixed potential with this method.
    Additional Material: 5 Ill.
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    Frictional coefficients of multisubunit structures. I. Theory (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 135-148 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The theory of Kirkwood for the translational frictional coefficients of structures composed of subunits has been generalized in two ways in order to consider aggregates of nonidentical subunits. One of these generalizations fails when the sizes of subunits are too disparate; the other, derived from a surface shell distribution of frictional elements, is effective over the whole range of relative sizes. It is shown that, in the limit of a continuous surface distribution, a shell model reproduces Stoke's law for a sphere. Comparison is made between the frictional coefficients of spheres, ellipsoids, and rods modeled by finite numbers of subunits and by continuous shells of frictional elements, and those calculated from other theories. Agreement is generally good, though the shell model for prolate ellipsoids of revolution deviates by a few per cent from the Perrin value.
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    Application of matrix rank analysis to the optical rotatory dispersion of TMV RNA (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 589-613 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The method of matrix rank analysis has been applied to a large body of experimental data to determine and identify the minimum number of independent spectral components that, were contained within it. The optical rotatory dispersion of TMV RNA was measured in the wavelength region 230-350 mμ, for a wide range of temperatures and ionic strengths. Over the whole range of conditions considered, the observed optical rotatory dispersion spectra were found to be a superposition of two basic spectra only. Evidence is put forward relating these spectra to the single-strand and double-strand helical forms of the molecule. A model is proposed to explain the observed spectral changes in terms of an equilibrium between these two conformations, which leads to a direct calculation of the percentage composition of the double strand at any of the conditions considered. This equilibrium, while simple in general description, appears multi-state and complex in detail. This method of analysis is both powerful and of wide applicability, since it is independent of the source of the data.
    Additional Material: 15 Ill.
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    Transient distributions arising from initially sharp boundaries in the ultracentrifugePresented at a meeting of the Physical Biochemistry Group, British Biophysical Society, King's College, London, Jan. 4, 1967. (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 663-672 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An infinite series solution to the Mason-Weaver equation is presented for the case in which a synthetic boundary is formed originally between solution and solvent. Digital computations based on this series, and confirmed independently, have been made for a range of parameters. For given conditions, the maximum rate of change of concentration at the meniscus and the time at which it occurs can be easily estimated by means of the curves presented. In equilibrium experiments which commence with formation of a sharp boundary, this enables the fringes to be identified with certainty.
    Additional Material: 6 Ill.
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    Experimental thermodynamics of the helix-random coil transition. I. Influence of polymer concentration and solvent composition in the PBG-DCA-EDC system (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 649-662 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The course of the reversible helix formation of poly(γ-benzyl L-glutamate) (PBG) dissolved in a mixture of dichloroacetic acid (DCA) and 1,2-dichloroethane (EDC) was followed by measuring the heat capacity and the optical rotation of the system through the transition region. The results of these measurements indicate that the transition enthalpy ΔH the transition temperature Tc, and the Zimm-Bragg parameter σ depend considerably on the PBG concentration as well as on the composition of the solvent. For the standard state of infinite dilution, however, a linear extrapolation of the measured ΔH if values results in a standard value ΔH° = 950 cal./mole, independent of the solvent composition. The results of the calorimetric measurements are discussed in relationship to changes in optical rotation. Some peculiarities in the measured thermodynamic and optical properties in solutions with relatively high content of dichloroacetic acid are reported.
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    General method for calculating helical parameters of polymer chains from bond lengths, bond angles, and internal-rotation angles (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 673-679 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Helical conformations of infinite polymer chains may be described by the helical parameters, d and θ (the translation along the helix axis and the angle of rotation about the axis per repeat unit), pi (the distance of the ith atom from the axis), dij, and dij (the translation along the axis and the angle of rotation, respectively, on passing from the ith atom to the jth). A general method has been worked out for calculating all those helical parameters from the bond lengths, bond angles, and internal-rotation angles. The positions of the main chain and side chain atoms with respect to the axis may also be calculated. All the equations are applicable to any helical polymer chain and are readily programmed for electronic computers. A method is also presented for calculating the partial derivatives of helical parameters with respect to molecular parameters.
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    Volume changes accompanying collagen denaturation (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 685-689 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A dilatometric technique is employed to measure the volume changes occurring on denaturation of collagen solutions and tendons. Partial specific volumes of tropocollagen are calculated to be 0.686 ml./g. in water and 0.689 ml/g in 0.1M citrate buffer. From data on non-aqueous solutions, it is estimated that most of the volume change arises from changes in polymer configuration rather than from changes in solvation.
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    Numerical solutions of the Lamm equation. III. Velocity centrifugation (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 697-713 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have generated solutions to the Lamm equation to examine the effects of concentration dependence on velocity experiments. Two forms of c dependence are considered: s/s0 = 1 - kc and s/s0 = (1 + kc)-1. Features of these solutions are discussed. The magnitude of the errors resulting from the usual procedure of measuring the rate of movement of schlieren maxima or of the position at which the concentration is one half the plateau value have been examined. These errors are usually negligible after sufficient centrifugation time. The errors in using the half-plateau concentration are less than those using the movement of the peak. We have also examined a technique due to Fujita for determining D from boundary spreading when s/s0 = (1+kc)-1. This method is satisfactory when s/s0 is actually of this form, or under certain limitations when s/s0 = (1 + kc)-1. Creeth has shown that under certain conditions the concentration gradient, curve remains virtually unchanged in shape after separating from the meniscus. When this occurs it is possible to estimate s/D from the data. The condition for such a steady state is that kc0 be sufficiently large. Numerical confirmation of this method is presented in the final section.
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    Variation in the intensity of scattered light by solutions of DNA subjected to an electric field (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 723-726 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preliminary experiments have been carried out which measure the variation in the intensity of the light scattered by DNA solutions under the influence of an electric field. Data have been collected on the length of DNA molecules, their electric polarizability, and their dispersion behavior.
    Additional Material: 3 Ill.
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    Topography of nucleic acid helices in solutions. II. Structure of the double-stranded rA-rU, rI-rC, acid rA, and the triple-stranded rA-rU2 and rA-rI2 helices (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 727-747 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Information concerning the structures of rA-rU, rA-rU2 rI-rC, rA-rI2, and acid rA helices in solutions is reported. Through the use of diquaternary ammonium salts of the general structure, \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm R}_1 {\rm R}_2 {\rm R}_3 \mathop {\rm N}\limits^ + ({\rm CH}_2 )n\mathop {\rm N}\limits^ + {\rm R}_1 {\rm R}_2 {\rm R}_3 \cdot 2{\rm Br}^ - $\end{document} (I), it is shown that (1) the distances between adjacent negatively charged oxygen atoms on the helix increases in the following order rA-rI2 〈 rI-rC 〈 rA-rU ≤ rA-rU2; (2) the density of the helices increases in the order. rA-rI2 〈 rA-rU 〈 rA-rU2 〈 rI-rC; (3) there is a large hydrophobia site in rA-rI2 and possibly also in rA-rU, rA-rU2, and rI-rC helices; (4) the results of the interactions between the salts of type I and the helices may be formulated in semi-quantitative terms by the use of two parameters, α, and β which are shown to be related to the charge separation and the density of the helices, respectively; (5) the studies in solutions compare favorably with the x-ray studies on the fibers; and (6) the acid rA helix differs significantly from the other helices by the fact that the electrostatic interstrand interactions between the negatively charged oxygen atom of a phosphate group and the positively charged 10-amino group of adenine contribute significantly to the stabilization of the helix, and thus it is found that the presence of the salts, I, leads to a significant destabilization of the acid rA helix.
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    Noncomplementarity in base sequences between the cohesive ends of coliphages 186 and λ and the formation of interlocked rings between the two DNA's (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 953-966 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The half molecules of 186 DNA have been isolated by the Hg(II)-Cs2SO4 density gradient centrifugal ion technique. The buoyant densities of the two halves in CsCI at 25°C. are 1.713 and 1.709 g./cm.3, corresponding to GC contents of 54% and 50%, respectively. Similarly, 5-bromouracil labeled λ DNA halves were separated. The isolation of the four DNA halves made it possible to test for homology in base sequences between the cohesive ends of λ and those of 186. There was no indication of any significant homology in base sequences between the cohesive ends of the two DNA's, as indicated by the absence of a band with intermediate buoyant density in CsCI when either half of 186 DNA was annealed with either half of 5-bromouracil labeled λ DNA and then centrifuged. The lack of cohesion between the two DNA's made it possible to demonstrate unequivocally the formation of interlocked rings (catenanes) between the two DNA's. The existence of a dimeric catenane is evidenced by the formation of a species of intermediate buoyant density when 5-bromouracil labeled λ DNA is cyclized in the presence of cyclic 186 DNA of a relatively high concentration. The molecular weight of one DNA relative to the other can be calculated from the position of the dimeric catenane in a density gradient by using the method of Baldwin. The result was in complete agreement with our previous measurements from the sedimentation coefficients and by electron microscopy. The probability of dimeric catenane formation when one DNA is cyclized in the presence of another DNA is discussed. The experimental results agree with the theoretical expectation.
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    Masthead (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967) 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/bip.1967.360050901
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    Conformational analysis of poly-N-methyl-L-alanine (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 815-820 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sterically allowed forms of the poly-N-methyl-L-alanine chain were found by calculation of conformational energies as a function of the rotation angles of its chain bonds. The lowest energy form seems to be a right-handed, approximately threefold helix.
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    X-Ray diffraction of oriented amylose fibers. II. Structure of V amyloses (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 837-845 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oriented amylose fibers in the V form were prepared and subjected to x-ray analysis. Unit cells and the probable space group of P212121 were determined for the V anhydrous and V hydrate forms of amylose; the analysis confirms previous predictions of these structures based on x-ray powder patterns. Chain folding in V amyloses is discussed in view of crystallographic evidence and folding experiments conducted with space-filling models. Reported also is evidence for amylose helices having diameters intermediate between 13.0 and 13.7 A.
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    Conformational aspects of polypeptides. XXIV. Conformational energies of poly-N-methyl-L-alanine chainsFor previous paper in this series, see Goodman and Falxa. (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 809-814 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational energies of the poly-N-methyl-L-alanine chain have been calculated as a function of the rotational angles of its skeletal bonds, taking into account torsional potentials, van der Waals repulsions, and London attractions. Four pronounced minima in the energy were found; the relative magnitudes of the energies at these minima suggest that the preferred conformation of this chain is either a right-handed, approximately threefold helix, or a slightly distorted, left-handed α-helix. Inclusion of an estimate of the dipolar contribution to the total conformational energy does not significantly affect this conclusion.
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    Molecular configuration of amylose and its complexes in aqueous solutions. Part III. Investigation of the DP distribution of helical segments in amylose-iodine complexes (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 17-26 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The equilibrium normality [If] of free iodine in amylose-iodine complex formation is a function of the length of the polyiodine chains. This length depends on the DP of helical segments of amylose (sDPn). Values of [If] and of the concentration of the bound iodine [Ib] were determined by the continuous photometric titration with automatic recording. Plots of [Ib] versus [If] give an integral distribution curve. Since the relation between [If] and sDPn is known, the graphic differentiation of the [Ib] versus [lf] curve furnishes the differential distribution curve, representing the mass distribution of the helical segments according to their DP. The peak of this curve is characteristic of the percentage and DP of those helical segments, which occur in the largest amount. On the basis of the differential distribution curve the polymolecularity of the investigated sample may be judged. The titration of amylose samples degraded by various methods gives different distribution curves. Titrating mixtures of samples with widely differing average DP values results in differential curves having more than one maximum.
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    Structure and optical activity of the DNA-aminoacridine complex (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 79-94 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electronic absorption and circular dichroism spectra of the DNA-acridine orange complex have been measured over a range of ionic strength, pH, and DNA phosphate to dye (P/D) ratios. Three circular dichroism bands associated with the long wavelength absorption band of acridine orange are induced on complex formation with DNA. Two of the dichroism bands, due mainly to dimeric dye molecules, are favored by low ionic strength, low pH (3.2), and a low P/D ratio (∼3), while the third, deriving primarily from monomeric dye, is optimum at high ionic strength, neutral pH, and a larger P/D ratio (9). The data suggest that monomeric acridine orange binds to DNA in the form of a left-handed helical array with four dye molecules per turn, while the bound dimer has a skewed sandwich conformation which is itself dissymmetric. The stereochemical relations between the bound monomer dye and the DNA are consistent with a modified intercalation model for the DNA-acridine complex.
    Additional Material: 7 Ill.
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    α-Helix formation by solvent-solvent interaction (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 69-77 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The degree of helicity θ of a series of homologous polypeptides as a function of solvent composition was investigated. The polypeptides studied were: poly-N5-(3-hydroxypropyl)-L-glutamine (PHPG) as well as the corresponding 2-hydroxyethyl and 4-hydoxybutyl derivatives (PHKG and PHBG, respectively). PHPG, which is nonhelical in formic acid, attains helicity on addition of relatively small amounts of formates, formamide, and urea to its solution in formic acid. This demonstrates that the high acidity of pure formic acid is largely responsible for its helix-breaking power-probably through protonation of the peptide bonds. In formic acid-water mixtures all three polymers show a maximum in degree of helicity at a mole fraction of about 0.3 formic acid. This is interpreted as being due to interaction between the two helix-breaking solvents, which results in the formation of an inactive molecular species. It is shown that solvent-induced transitions with helicity maxima are predicted by the Bixon-Lifson treatment when applied to this system.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1967.360050108
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    Molecular configuration of amylose and its complexes in aqueous solutions. Part IV. Determination of DP of amylose by measuring the concentration of free iodine in solution of amylose-iodine complex (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 27-41 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In aqueous solutions of the amylase-iodine complex the concentration of free iodine [If]v after reaching equilibrium (or closely approximating it) is determined by the following factors: temperature, pH, concentration of iodide ions and amylose, and DP of amylose. In the present paper the role of temperature, amylose concentration, and DP has been investigated. At half-saturation of amylose by iodine, the reciprocal value of free iodine defines the equilibrium constant: 1/[If]v = K. The relation between [If]v, in normality and temperature is the following: 5 + log [If]v = -(2.132/T) + 8.52, for DPn = 1290, 0.4 mg. amylose in 100 ml. 0.1N HCl. The value of the energy of activation Ea between 2 and 52°C. is 9.72 kcal./mole. The influence of amylose concentration [Am] on photometrically determined [If]v, at 20°C, in the range of 0.1-1.2 mg./100 ml. 0.1 N HCl for DPn = 1290 is: 5 + log [If]v = 0.209 - 0.047 log [Am]. At [Am] = 0.6 mg. amylose/ 100 ml. 0.1 N HCl and 20°C, the value of [If]v depends on DPn as follows: 5 + log [If]v = 0.085 = + 0.222 log (104/DPn). These above equations are summarized by the relation: [If]v = exp {16.865 - (Ea/RT)}[Am]0.047(104/DPn)0.222 ×10-5 Considering that the determination of [If]v by automatic photometric titration can be performed quickly and with appropriate reproducibility, this method is convenient for a rapid empirical and approximate determination of DP of amylose on a microscale. The iodine-binding capacity [IBC] as well as the value of λmax, have been also investigated as functions of DPn, by photometric and by amperometric titration.
    Additional Material: 6 Ill.
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    Dielectric properties and oxygenation of hemoglobin (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 879-886 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dielectric properties of human and horse hemoglobin were studied at frequencies ranging from 20 kc./sec. to 7 Mc./sec. The relative errors in the measurements were usually less than 10-3 even for mildly conducting solutions (10-3M KCl). The experimental setup allowed us variation and measurement of the degree of oxygenation of the protein and to determine its dielectric parameters. Our main conclusion is that it was not possible to find any variation of the dielectric increment for hemoglobin oxygenation levels of 25, 50, 75, and 100%, approximately. This result is at variance with some previous reports. We cannot give the reason for this discrepancy but discuss some possible explanations. The specific dielectric increment, Δεs/c, of human hemoglobin was shown to be significantly smaller than that of horse hemoglobin (0.28 against 0.32). This physical property is lowered with increasing ionic strength I: Δεs/c = 0.28 and 0.20 for I = 10-4 and 10-3, respectively (human protein).
    Additional Material: 3 Ill.
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    Transient electric birefringence studies of T2 bacteriophage and T2 ghost (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 415-430 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The transient electric birefringence behavior of bacteriophage T2 and the T2 ghost or protein coal was studied. The field free relaxation measurements show both the intact virus and its ghost to have two rotary diffusion coefficients. These coefficients have values of 555 ± 54 and 111 ± 22 sec.-1 for the intact virus and 688 ± 89 and 161 ± 29 sec.-l for the ghost. The equivalent ellipsoids for the fast and slow relaxation coefficients were obtained by use of Perrin's equation and were related to the bacteriophage structure in terms of a possible extension of the tail fibers or an enlargement of the head structure. The saturation of the specific birefringence of the phage and the ghost when compared with the specific birefringence of the free nucleic acid gave an average optical orientation of 10 to 18% of the nucleic acid parallel to the main axis of the phage. The analysis of the birefringence versus applied field strength in the Kerr region gave the following values for the anisotropy of the polarixability. αe,33 - αe,11 and intrinsic dipole, μ, of both phage and ghost : for T2 phage αe,33 - αe,11 = 5.0 × 10-14 cm.3 and μ = 64,400 Debyes; for T2 ghost αe,33 - αe,11 = 7.9 × 10-14cm.3 and μ = 57,200 Debyes. The high intrinsic dipole for phage and ghost is interpreted as to be associated with the mechanisms of the virus for attachment, to the host cell wall.
    Additional Material: 8 Ill.
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    Masthead (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968) 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Hydration of polyacids (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 431-440 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The hydration of several polyacids has been investigated with special attention to the effects of neighboring charged groups and hydrophobic groups on the hydration regions. The molar volume change due to the structural change of water by the hydration was obtained by the method of refractivity measurement. The polyacids employed were poly(acrylic acid), poly(methacrylic acid), poly(L-glutamic acid), and a copolymer of maleic acid and vinyl acetate. The measurement of the refractive index was performed for the solutions of these polymers neutralized to varying degrees by tetrabutyl-ammonium hydroxide and sodium hydroxide. The results confirm the characteristics of the previous model of the hydration of polyelectrolytes, that is, the cooperative action of neighboring charged groups induce the second hydration region in addition to the intrinsic hydration region. The stiff structure of water in these regions restricts the mobility of counterions forced to enter into these regions by the strong electrostatic potential of polyions. The results indicate also that hydrophobic groups induce an additional hydration region around their neighboring charged groups. Small but negative volume changes were observed for conformational changes of poly(L-glutamic acid) and poly(methacrylic acid) induced by the neutralization of carboxyl groups.
    Additional Material: 6 Ill.
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    Enthalpy of helix-coil transitions from heats of solution. I. Polyglutamates. (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 441-448 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The heat of solution of a series of three polyglutamates as a function of solvent composition was measured. The abrupt increase in heat of solution at the solvent composition of the helix-coil transition (as evidenced by optical rotation data) allows the estimation of the transition enthalpy change. The difference of side chain in the three polyglutamates has no appreciable effect on the transition enthalpy, although it affects the helix stability, as judged from the solvent composition at the transition points. These facts are discussed on the basis of existing models of the transition.
    Additional Material: 5 Ill.
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    Epitaxial crystallization of poly (γ-benzyl L-glutamate) on alkali halide single crystals (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 469-477 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
    Notes: Single crystals of poly(γ-benzyl L-glutamate) were formed by epitaxial crystallization from solution in mesitylene on NaCl, KI, and KCl (001) cleavage faces. From electron microscopy and diffraction studies, the structure of these overgrowths was determined to be that of lamellae containing chain-folded α-helical macromolecules. The usual type of crystal perfection, that of ordered helix axes and disordered side groups, was exhibited by this synthetic polypeptide. Unique orientation regimes were observed with each substrate.
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    Kinetics of reversible reactions on linear lattices with neighbor effects (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 479-490 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As a model for a variety of reaction processes on long chain molecules, for example, helix formation, a kinetic theory on a linear lattice is presented. Each reaction site can undergo reversible transitions between two states (0 and 1) with rates depending on the slate of its nearest neighbors. The system of coupled rate equations for the frequencies of specified runs of 0's and 1's is infinite for an infinite chain. In contrast to the case of irreversible processes, the system cannot, be written down by inspection. A procedure for the systematic derivation of the rate equations is developed which can be programmed on a computer. Explicit expressions for runs up to length four, involving runs up to length five are obtained without recourse to the computer. For the solution of the rate equations a closure must necessarily be imposed, and a possible procedure is pointed out. Furthermore the equilibrium relations following from the model are considered. The well-known equilibrium results for nearest-neighbor interactions represent a special case of these equations.
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    Specific heat studies of various wool-water systems (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1355-1377 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Measurements of specific heat of wool-water systems were made at approximately 5°C intervals over the temperature range -70 to 100°C. Ten different, samples were used, each with a different amount of absorbed water in the range from dry ness to saturation at 0°C. The graph of specific heat against temperature for dry wool is precisely linear over the complete temperature range, suggesting that thermal motion is entirely vibrational. When absorbed water is present the data can be conveniently discussed in terms of behavior below and above an amount of absorbed water of 22.7 g in 100 g of wool (22.7% of absorbed water). Below 22.7% there is only one temperature range in which the results indicate an appreciable transition in heat absorbing properties. The temperature of transition depends on water content but is higher than 0°C. Above 22.7% a second transition appears in the range -30 to 0°C and grows rapidly larger with increase of water content. The first transition is tentatively ascribed to a slightly cooperative breakdown of polar bonds in wool, and the second to a process analogous to melting in the absorbed water. The results are discussed in these terms as well as with reference to specific heat theories, the heat absorption of the wool component and the water component, and enthalpy differences between the various samples.
    Additional Material: 11 Ill.
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    New chain conformations of poly(glutamic acid) and polylysine (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1379-1382 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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    The helix-coil transition of poly-L-lysine in methanol-water solvent mixtures (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1383-1386 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
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    Kinetic properties and the electric field effect of life helix-coil transition of poly(γ-benzyl L-glutamate) determined from dielectric relaxation measurements (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1263-1277 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dielectric relaxation of poly(γ-benzyl L-glutamate) in solution has been studied in the 5 kcps-10 Mcps range for various values of the helix content. The results give first experimental evidence for three effects of major significance. (1) The system exhibits dielectric relaxation due to a chemical rate process (namely helix formation). This confirms recent theoretical predictions. (2) The mean relaxation time τ* of the helix-coil transition could be evaluated as a function of the degree of transition. The results are in excellent agreement with a previously developed theory. At the midpoint of transition it is found τ*max = 5 × 10-7 sec. The elementary process of helical growth turns out to be practically diffusion-controlled (with a rate constant of hydrogen bond formation of 1.3 × 1010 sec-1). (3) There is a considerable electric field effect of the helix-coil transition. This indicates that conformation changes in biological systems could be potentially caused by direct action of an electric field.
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    A general method for calculating helical parameters of polymer chains from bond lengths, bond angles, and internal-rotation angles (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1387-1388 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Proton magnetic resonance study of the binding of purine to polyuridylic acid (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 983-991 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The interaction of unsubstituted purine with polyuridylic acid in D2O solution at neutral pD has been studied by high resolution proton magnetic resonance spectroscopy. The poly U proton resonances were shifted to higher fields by the added purine, indicating that purine binds to the uracil bases of the polymer by base stacking. Severe broadening of the purine proton resonances was also observed, providing strong evidence for the intercalation of purine between adjacent uracil bases of the polymer. The line widths of the poly U proton resonances were not noticeably broadened in the presence of purine; thus, the binding of purine to poly U does not result in a more rigid or ordered structure for the polymer.
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    Study of collagen denaturation kinetics by dynamic mechanical methods (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 997-1000 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
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    Thermal degradation of proteins studied by mass spectrometry (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1001-1004 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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    Masthead (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968) 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Viscosity study of DNA. II. The effect of simple salt concentration on the viscosity of high molecular weight DNA and application of viscometry to the study of DNA isolated from T4 and T5 bacteriophage mutants (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1005-1018 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polyelectrolyte expansion effects on high molecular weight bacteriophage DNA have been studied by examining the influence of simple salt concentration upon the intrinsic viscosity, [η]. The viscosity-molecular weight exponent a in the expression [η] = KMa diminishes from 0.8 in 0.005M simple salt to a limiting value of 0.6 for salt concentrations greater than 0.6M at 25°C. The ε parameter of the N1+ε hydrodynamic representation thus varies from approximately 0.2-0.07 over this range of salt concentration. The intrinsic, viscosity of DNA decreases slightly with increasing temperature at low and moderate salt concentrations but becomes independent of temperature at high salt concentrations. The expansion of the DNA molecular domain is linear in the reciprocal square root of the simple salt concentration. Viscosity differences among DNA's isolated from several bacteriophage T5 mutants reflect small differences in molecular weight which are in agreement, with sine determination by other techniques. The DNA's isolated from various rII mutants of T4 bacteriophage including some very large deletion mutations were found to be identically the same size in accord with current genetic ideas. Details of the representation and extrapolation of viscosity data are discussed and the sensitivity of the technique is evaluated.
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    Conformations of model compounds of proteins. I. Acetylglycine N-methylamide (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1037-1076 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
    Notes: Infrared spectra in the region 4000-60 cm-1 have been measured for acetylglycine N-methylamide and its deuterium homologs, CD3CONHCH2CONHCH3, CH3-CONHCD2CONHCH3, CH2CONHCH2CONHCD3, and CH3CONDCH2CONDCH3. Normal frequencies have also been calculated for these molecules with various conformations. The spectra show that this compound has two crystalline modifications, form A and form B. The frequencies and their isotope shifts show that the molecular conformation (Ψ, φ) of form B is near (0, 120) and that of form A near (180, 120). The short-range factors determining the conformation of peptide backbone having glycine residues are discussed.
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    Potentiometric titrations and the helix-coil transition of poly(L-glutamic acid) and poly-L-lysine in aqueous salt solutions (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1019-1036 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The objective have been to establish if those ions which are known to change the stability of the structure of proteins, have any influence on the properties of ionizable polypeptides. Potentiometric titrations and complementary optical rotation data are presented for aqueous solutions of poly-L-lysine (PLL) in the presence of KSCN, KCl, and KF, and for poly(L-glutamic acid) (PLGA) in the presence of KSCN, KCl, and LiCl. The following measured quantities which are affected by salt concentration were obtained: intrinsic pK (pK0), slope of pKapp versus degree of ionization (α) curves, the degree of ionization at which the helix to coil transition occurs, and the free energy of this transition for the uncharged molecule (δG°hel). The effects of nonspecific salts (KCl and LiCl for PLL and KSCN and KCl for PLGA) are small, and about, as expected from general electrostatic considerations. In line with the observations made with isoelectric and cat ionic collagen, specific, effects were noted with KSCN-PLL and with LiCl-PLGA. In the presence of KSCN, the poly-L-lysine helix becomes stabilized at much lower degree of ionization than in the presence of KCl, and the slope of the pKapp versus α plots is greatly reduced. However, ΔG°hel (for the uncharged molecule) is not affected, and pK0 is only slightly higher. We interpret these data in terms of binding of SCN- primarily to the side-chain amino groups (both to R—NH3+ and to R—NH2) solutions. (L-glutamic acid) in LiCl solution has its transition at the same α value as in KCl solution. However, both the slopes of the pKapp versus α plots and the absolute values of ΔG°hel are lower than in KCl solution. We interpret these results in terms of binding of Li+ to side chains as well as to the peptide bond.
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    Deoxyribonueleate solutions: Sedimentation in a density gradient, partial specific volumes, density and refractive index increments, and preferential interactions (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1077-1100 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Density increments (∂ρ/∂c2)°μ in solutions of NaDNA in NaCl and CsDNA in CsCl were determined over a wide range of salt concentrations; calf thymus DNA, fragmented by sonic irradiation to a molecular weight of 4-6 × 105 was used. The partial specific volume v̄2° of NaDNA at 25°C was found to ho 0.500 ml/g in water, and that of CsDNA 0.440 ml/g. Both values increase with increasing NaCl and CsCl concentration. Refractive index increments under various experimental conditions were also determined. The relevance of the density increments (at constant, chemical potential of diffusible solutes) to equilibrium sedimentation in a density gradient and the evaluation of molecular weights is discussed. Distribution coefficients of diffusible components, sometimes referred to as preferential solvation or net hydration, were derived from the density increments and partial volumes and compared with direct experimental results, whenever available, from membrane distribution and isopiestic distillation. The thermo-dynamic significance of the distribution coefficients as well as possible interpretations in terms of specific molecular mechanisms are considered.
    Additional Material: 6 Ill.
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    Models for hemoglobin and allosteric enzymes (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1101-1118 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A model for hemoglobin is proposed and its application to allosteric enzymes is discussed with particular reference to asparate transcarbamylase. The main assumptions made are that the molecule is composed of subunits and that occupation of a sub-unit produces a conformational change which affects the occupational probability of neighboring subunits. The results compare favorably with experiment and a number of specific predictions are made for aspartate transcarbamylase.
    Additional Material: 6 Ill.
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  • 81
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    X-ray diffraction of oriented amylose fibers. III. The structure of amylose-n-butanol complexes (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1119-1128 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexes of amylose with n-butanol were prepared both as crystalline precipitates and as oriented fibers. These complexes were subjected to x-ray analysis, their unit cells were calculated, and the space group of P212121 was confirmed. n-Butanol complexes exist in both hydrated and anhydrous forms. There is no evidence for methanol, ethanol, or n-propanol structures similar to those shown by the n-butanol complex. The Complexes are unstable in the open air and revert to V-amylose hydrate on standing.
    Additional Material: 2 Ill.
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    Mechanochemical melting of collagen fibers. II. Diffusion-controlled contractions (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1147-1158 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Collagen fibers were contracted “chemically,” i.e., by transferring them from water into KCNS solutions either isometrically or isotonically. Both changes in force and fiber length and in salt and water contents were measured as functions of time. The mechanical changes were found to follow the diffusional processes. The diffusion of water exhibited a plasmolytie effect. The role of water in the melting process is discussed.
    Additional Material: 9 Ill.
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  • 83
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    Mechanochemical melting of collagen fibers. I. Mechanical contractions (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1129-1145 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The correlation between mechanical and chemical Processes in the contractile system collagen fibers-aqueous KCNS sulutions was investigated. Melting and contraction of the fibers were induced by applying a force sufficiently high as to prevent melting in a KCNS solution and then decreasing it either suddenly, or continuously at a constant rate. The kinetics of both processes are characterized by an initial rapid elastic response of the crystalline collagen, followed by a stationary region. The force-velocity relationship in this region was found to be the same under different types of mechanical deformations. It is probable that under the prevailing conditions, the behavior in the stationary state is determined by the melting process and is not markedly influenced by diffusional changes. Part of the experimental data could be explained by assuming a linear, rigid model or, better, by taking into account the highly elastic properties of the amorphous collagen. The kinetic, unit seems to be composed of several hundred amino acid residues.
    Additional Material: 10 Ill.
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  • 84
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    Dynamic-elastic investigation of the chemical denaturation of collagen fibers (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1159-1168 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dynamic elastic behavior of collagen fibers treated by LiBr solutions was studied by the method of free longitudinal vibrations. The frequency response functions and the stress-strain relationship were evaluated for fibers denatured to different extents by various concentrations of the salt solution. The James and Guth model for rubber elasticity was applied to the experimental data. The elastometric parameter β, which is a measure of the degree of folding of the macromolecular chains, was found to decrease on increasing the salt concentration. It might thus serve as a characteristic of the degree of denaturation of fibrillar proteins.
    Additional Material: 6 Ill.
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    Need for nonplanar peptide units in polypeptide chainsContribution No. 233 from the Centre of Advanced Study in Biophysics, University of Madras, Madras-25, India. (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1494-1496 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1968.360061013
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    Theory of gel filtration separation of biopolymers assuming a Gaussian distribution of pore sizes (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1497-1499 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/bip.1968.360061014
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  • 87
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    On the limiting sedimentation coefficients of polyelectrolytes (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1500-1502 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/bip.1968.360061015
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  • 88
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    Strain-stress isotherm of keratin fibers (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1503-1506 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1968.360061016
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    Detection and enthalpy of vaporization of bound water in biopolymers by DTA (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1507-1508 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 90
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    Optical properties of DNA in ethylene glycol (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1509-1514 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1968.360061018
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  • 91
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    Pseudo-phase diagrams of poly-L-lysine and poly(L-glutamic acid) in aqueous salt solutions (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1213-1217 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1968.360060815
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    Masthead (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968) 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/bip.1968.360061101
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    Ionic polysaccharides. II. Comparison of polyelectrolyte behavior of hyaluronatc with that of carboxymethyl cellulose (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1519-1529 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sodium hyaluronate (NaHy) and sodium carboxymethyl cellulose (NaCMC) behave similarly with respect to concentration.N 3 of an added 1 : 1 electrolyte. The second virial coefficient A2 (light scattering) is identical within experimental error at a given.N 3. The limiting viscosity number [η] also varies with N3-1/2in similar fashion for samples of similar [η] of the two polymers. Differences in Na+ activity in salt-free solutions are interpreted on the basis of weaker Na+ binding in NaHy, presumably due to the greater charge separation along its chain backbone. Added electrolyte is excluded in dialysis more strongly by NaHy (or its acid form) than by NaCMC. The Flory parameter Φ is smaller in good solvents for NaHy, as for many other polyelectrolytes, than for nonionic polymers.
    Additional Material: 3 Ill.
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    Conformations of poly-L-valine in solution (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1551-1571 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to test theoretical predictions that poly-L-valine can exist in an α-helical conformation, water-soluble block copolymers of L-valine and D, L-lysine were prepared. By carrying out the synthesis on a resin support (with the use of N-carboxyanhydrides) contamination of the individual blocks by any unreacted monomer from the previous block was avoided. A single glycine residue was incorporated at the C-terminus of the chain for use in amino acid analyses. Using optical rotatory dispersion and circular dichroism criteria, about 50% of the short valine block of (D, L-lysine HCl)18-(L-valine)15-(D, L-lysine-HCl)16-glycine was found to be in the right-handed α-helical conformation in 98% aqueous methanol, in water, the polymer appears to be a dimer, with the valine block being involved in the formation of an intermolecular β-structure.
    Additional Material: 8 Ill.
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    Effect of side chains on the conformational energy and rotational strength of the n-π*transition for some α-helical poly-α-amino acids (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1531-1550 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Calculations of the dependence of the conformational energy and the rotational strength of the amide n-π* electronic transition (in a series of α-helical polyhel-α- amino acids with different side chains) on conformation have been carried out. The conformational energies were computed by procedures developed in this laboratory; the computation of rotational strengths was carried out by the method of Schellman and Oriel, with a slight modification. Polyamino acids with both nonpolar and polar side chains were considered; in the latter case, it was assumed that the only influence of the polar side chain was on the backbone conformation and on the electrostatic field which perturbs the amide chromophore of the backbone. Only conformations in the range of backbone dihedral angles of the right- and left-handed a-helices were considered, and the assumption of regularity (i.e., uniformity of dihedral angles in every residue) was made. The rotational strength per residue was found to vary markedly with chain length (in oligomers of up to 40 residues long); both the conformational energy per residue and the rotational strength per residue were found to vary significantly with the backbone conformation, which in turn depends on the nature of the side chain. The geometry of the hydrogen bond in the α-helical backbone is the most important factor which influences the dependence of the rotational strength on conformation. The implications of these results, for the interpretation of experimental circular dichroism and optical rotatory dispersion data, are discussed.
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    Interaction of heat-denatured HeLa cell DNA with synthetic and natural polysaccharides (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1573-1578 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heat-denatured DNA from HeLa cells interacts with natural as well as synthetic polysaccharides. Glucose does not inhibit the interaction nor will it produce it. Polysaccharides with a molecular weight of 10000 or greater are required before the interaction takes place.
    Additional Material: 4 Ill.
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    Conformational aspects of polypeptides. XXV. Solvent and temperature effects on the conformations of copolymers of benzyl and methyl L-aspartate with nitrobenzyl L-aspartateFor previous paper in this series, see Mark and Goodman. (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1579-1603 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of copolymers of β-p-nitrobenzyl L-aspartate with β-benzyl L-aspartate and with β-mcthyl L-aspartatc in helix-supporting and helix-breaking conditions have been reexamined by using ultraviolet isotropic, absorption, optical rotatory dispersion, and circular dichroism techniques. Many different conformations are apparent, depending on solvent and temperature. Chloroform, trifluoroethanol, and methylene dichloride support the left-handed helical conformation of the copolymers containing less than about 20 mole-% nitroaromatic residues and the right-handed helical conformation of the copolymers containing more than approximately 30 mole-% nitroaromatic residues. In trifluoroacetic acid all the copolymers are in a random-coil conformation. In hexa-fluoroacetone trihydrate and in trimethyl phosphate, the copolypeptides with low nitroaromatic residues content are predominantly in a disordered conformation, while those with high nitroaromatic residues content show a right-handed helical array. Reversible helix-ramlom-coil transitions are observed with increasing temperature in trimethyl phosphate. An example of right-handed-left-handed helix reversible transition with temperature is reported in a chloroform-trimethyl phosphate (2:1) mixture. Nitrobenzyl-nilrobenzyl side-chain interactions in chloroform, but not in trifluoroacetic acid or in trimethyl phosphate, have been confirmed. For the first time we report the circular dichroism spectra in which the n-π* peptide band of a left-handed helical conformation is almost completely evident.
    Additional Material: 17 Ill.
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    Ultraviolet dichroic ratio of DNA from T2 and T5 bacteriophages (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1605-1631 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dichroic ratios of T5st-O and T2H bacteriophage DNA molecules were measured throughout the ultraviolet region of the spectrum. Two methods of DNA orientation were studied: (1) orientation in solution in a Shimadzu flow dichroism instrument attached to a Beckman DU spectrophotometer, and (2) alcohol precipitation of the DNA from solution and orientation in a thin film on the quartz face of a humidity chamber. Spectra in the latter case were recorded using a Gary Model 14 spectrophotomcter fitted with Glan prisms. The lower wavelength limit was 215 mμ in both systems. The DNA preparations were carefully characterized as to spectral purity, sedimentation coefficient, hyperchromicity, protein content, and DNA content. In addition, the structure of the DNA oriented in films was inferred from x-ray diffraction patterns of fibers of the precipitated DXA. The A and B configurations of DNA in films could not be distinguished by the dichroic ratio measuiements. The dichroic ratio obtained for the film-oriented DNA at high relative humidity shows the same wavelength dependence as for the flow-oriented DNA. The same wavelength dependence for DNA in the fibrous state and in solution, when considered together with the x-ray diffract ion results, indicates that DNA in solution maintains an orientation of bases which is similar to that in fibers. I1Or both solutions and films of DNA, the dichroic ratio is constant from 290mμ to 240 mμ and increases at wavelengths below 240 mμ. The increased parallel absorption below 240 mμ is consistent with the existence of an n→π* transition. The inherent molecular dichroic ratio is found to be the same for T5st-O DNA and T2H DNA in solution, and is a maximum of 0.09 ± 0.02 at 260 mμ.
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    Interaction between parallel rodlike macroions (1968)
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 1633-1647 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper gives a very simple method based on the characteristic property of the electric free energy to calculate the repulsive force between parallel rodlike macroions in a solution as a function of the charge density on rods. The total extensive force (∂f/∂X) of an assembly of m rods of length l and charge number n (charge density - neo /l) at small extension X in the absence of low molecular sals is given by where z is the valency of counterions and Q (= neO2/εkTl) is a dimensionless quantity representing the charge density. The repulsion between two parallel rods is given by putting m = 2. At large charge densities the repulsion is very much smaller than the direct coulomb force between charged rods, even at small distances. The addition of low molecular salts does not depress the repulsion appreciably, as long as the average concentration of salt ions is much smaller than the concentration of counterions accumulated in the space between rods. The effect of fluctuation of the coumerion distribution is also analyzed, and it is found that the attractive force due to the ion fluctuation may predominate over the above repulsive force in the case of polyvalent counterions and rods of high charge densities at small distances.
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    Effect of binding on melting transitions in polymer-diluent systems (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 773-783 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An expression is derived for the melting point of a polymer when in equilibrium with a solution in which binding of low molecular weight compounds to the polymer takes place. Allowance is made for the possibility that the crystalline polymer itself is a complex. The argument is a purely thermodynamic one and is based on a consideration of the change in free energy as a result of a change in binding. Allowance is made also for non-specific polymer-solvent interactions, in which the mixture of low molecular weight solvents is treated as a single solvent. Special attention is paid to “inverted” melting transitions, i.e., cases in which the melting point increases with increasing dilution of the polymer. It is shown that as a rule this is accompanied by a corresponding, inverted effect of the solvent composition on the melting point. It is further shown that-in the absence of binding, “normal” behavior at the critical point (i.e., phase separation is induced by lowering the temperature) is always accompanied by “normal” melting behavior (i.e., a decrease in melting point when the polymer is diluted). Also, “inverted” melting always implies that phase separation at the critical point is induced by heating, but the reverse is not necessarily true.
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    URL: http://dx.doi.org/10.1002/bip.1967.360050810
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