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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    International journal of biometeorology 34 (1990), S. 90-92 
    ISSN: 1432-1254
    Keywords: Rats ; Naproxen ; Hypoxia ; Organ weight
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract Rats were exposed intermittently for 8h per day over 6 days at simulated high altitude of 20 000 feet. One group of altitude-exposed animals was treated with naproxen, a prostaglandin inhibiting drug. Significant reduction in body weight gain was observed in both altitude-exposed and drug-treated altitude-exposed animals compared to the control group. Right and left ventricular weights and weights of the adrenal glands were increased significantly in altitude-exposed and altitude-exposed drug-treated animals. The weight of the spleen was increased significantly in altitude-exposed animals whereas no such increase of splenic weight was observed in drug-treated altitude-exposed group of animals. On the other hand, the weight of the liver was decreased significantly in both cases. In drug-treated altitude-exposed animals, the unaltered splenic weight was thought to be due to inhibition of the erythropoietic activity.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 175 (1990), S. 107-116 
    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 Beschreibung der Polymerisationsgeschwindigkeit der radikalischen Fallungspolymerisation von Acrylsäure in Toluol wurde ein Modell entewickelt. Die experimentelle Überprüfung des Modells erfolgte durch Messungen in einem isotherm betriebenen Reaktionskalorimeter. Das Modell beschreibt die Polymerisationsgeschwindigkeit bis zum vollständigen Umsatz in einem Temperaturbereich von 40 bis 60°C.
    Notes: A kinetic model for the free-radical precipitation polymerization of acrylic acid in toluene was developed and verified experimentally by using an isothermal reaction calorimeter. The model predicts the rate of polymerization accurately up to complete conversion in the temperature range of 40 to 60°C.
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  • 3
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    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 175 (1990), S. 157-168 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wird über Untersuchungen an Legierungen aus isotaktischem Polypropylen und EPDM-Elastomer berichtet, die mit hochenergetischen Elektronen bestrahlt worden waren. Die Mischungsverhältnisse in den Proben überstrichen sowohl den für elastomermodifizierte Thermoplaste typischen Bereich als auch den der thermoplasticschen Elastomeren. Eine Vernetzung der Komponenten über die Grenzfläche hinweg wurde nachgewiesen. Diese grenzflächenübergreifende Vernetzung bewirkte eine merkliche Verbesserung der mechanischen Eigenschaften insbesondere des thermoplastischen Elastomeren.
    Notes: Blends of isotactic polypropylene and EPDM rubber have been treated by electron irradiation in the composition range of rubber modification and in the thermoplastic rubber composition range as well. Mutual crosslinking of the components through the interface could be detected. This intercrosslinking caused a remarkable improvement of the mechanical properties particularly of the thermoplastic rubber.
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  • 4
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    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 175 (1990), S. 205-205 
    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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  • 5
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The mechanisms of photooxidation usually envisaged, are perfected by taking into account photoreactions of peroxy radicals. They involve interaction of a peroxy radical with the polymer to yield a hydroperoxy radical and a pair of macroradicals. After peroxidation, this pair will usually undergo bimolecular termination. The influence of such a reaction on photooxidation kinetics is particularly important for polyethylene. Then, chain termination occurs mainly by interaction of two hydroperoxy radicals or of a hydroperoxy radical with a macroperoxy radical. The reaction does not only affect kinetics of photooxidation but also the nature of the photooxidation products. The latter is more important for polypropylene than for polyethylene.
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  • 6
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Isothermal Differential Thermal Analysis was used to test the thermooxidative stability of pipes of polybutene during internal pressure tests at 110°C. At low hoop stresses and long testing times pipe failure was exclusively caused by thermooxidative degradation of the polymer.The stabilizer distribution in the initial state and its alteration during the pressure tests could easily be measured by isothermal DTA. Leaching of antioxidants from pipe walls could be detected. The decrease of residual thermooxidative stability was degressive.Degradation of pipe material started from the exterior pipe wall. Molecular weight of polybutene decreased rapidly after stabilizer exhaustion which could be observed by isothermal DTA.
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  • 7
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A base of experimental data on the ageing of commerial grade plastics is created. In includes assorted physical and chemical properties of plastics and their changes at natural ageing. An automated system for storing and processing of the experimental data is designed. Processing involves mathematical modeling of the changes in properties that aids in empirical prediction. The possibilities of the system are verified with experimental results from a 5-year ageing period of PE-LD and PE-HD. The results show a good agreement between the predicted and real data for selected models.
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  • 8
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    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 179 (1990), S. 35-56 
    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 Morphologie von Polypropylen-Spritzgußteilen mit Bindenaht wurde mit Röntgenweit-und Kleinwinkelstreuung, Lichtstreuung und Polarisationsmikroskopie untersucht. Die erhaltenen morphologischen Daten wurden mit mechanischen Werten aus Zugversuchen korreliert. Es wird gefunden, daß die mechanischen Eigenschaften der untersuchten Proben im wesentlichen von der sphärolithstruktur beeinflußt werden. Anhäufungen von Sphärolithen mit Kristallen der hexagonalen β-Modifikation und eine starke Inhomogenität der Sphärolithstruktur senkrecht zur Bindenaht sind der wesentliche Grund für die verschlechterten mechanischen Eigenschaften. Diese Sphärolithstruktur wird durch die Temperatur des Spritzgußwerkzeugs stark beeinflußt. Die Lamellen-Überstruktur hat dagegen einen vernachlässigbar kleinen Einfluß auf das mechanische Verhalten.
    Notes: The morphology of polypropylene plaques containing a weld line, has been investigated by x-ray wide and small angle scattering, light scattering and polarization microscopy. The results are correlated to mechanical values obtained from tensile tests. While the lamellar morphology is of neglectable influence, it is found, that the mechanical properties of the samples are strongly influenced by the spherulitic structure. Clustering of β-type spherulites and strong morphological inhomogeneities in the vicinity of the weld line are the primary reason for the mechanical weakening of the plaques. The temperature of the mould has a strong effect on the spherulitic structure and thus on the tensile properties of the samples.
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  • 9
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    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 179 (1990), S. 77-85 
    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: Füllstoffe für PVC- und PP-Formmassen wurden mit Mikrowellenplasma behandelt. Photoakustische FT-IR-Spektren zeigen, daß die Plasma-Polymerhülle auf der Füllstoffoberfläche —C=C—, —CH2—, CH3— und andere Gruppen enthält. Aus Röntgenelektronenspektren geht hervor, daß zwischen Siliciumdioxid und der organischen Beschichtung chemische Bindungen existieren. Durch Compoundieren von plasmabehandelten Füllstoffen mit PVC und PP werden Materialien mit guten mechanischen Eigenschaften bei niedrigen Kosten erhalten.
    Notes: Fillers for PVC and PP compounds have been treated by microwave plasma. FT-IR photoacoustic spectroscopy studies show that the plasma polymer sheath on filler's surface contains —C=C—, —CH2—, —CH3 groups, etc. X-ray photoelectron spectroscopy studies reveal that interfacial chemical bondings exist between silica and the organic coating. Application of plasma-treated fillers in PVC and PP compounds gives rise to materials of good mechanical properties and low cost.
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  • 10
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    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 179 (1990), S. 135-148 
    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-(alkylenadipat)-diole mit Molmassen von 1500, 2000 und 3000 wurden bei Temperaturen von 25 und 60°C in Gegenwart verschiedener Alkohole und unterschiedlicher PUR-Katalysatoren (1,4-Diazabicyclo[2.2.2]octan (DABCO), Dibutylzinndilaurat (DBTL),Dibutylzinndiethoxid (DBTEO) und Dibutylzinnoxid (DBTO)) in Ethylacetat bzw. Toluol gelagert und die Alkoholyse verfolgt. Die erhaltenen Ergebnisse werden mit dem Alkoholyseverhalten verschiedener Dialkyladipate sowie des Lösungsmittels Ethylacetat unter den selben Bedingungen verglichen. Die Alkoholyse verlauft in Gegenwart der zinnorganischen Verbindungen etwa mit gleicher Geschwindigkeit, ohne daß diese selbst signifikant zersetzt werden, wahrend DABCO praktisch inaktiv ist. Die Aktivitat der Alkohole ist starker von ihrer sterischen Struktur als von ihrer Basizitat abhangig. Die Stabilität der Polyalkylenadipate gegenüber einer Umesterung nimmt mit der Lange der Diolalkyleneinheiten des Polyols zu. Die Umesterung von Adipinsäuredialkylestern findet auch partiell in Anwesenheit eines großen Uberschusses an Ethylacetat statt.
    Notes: Poly(alkylene adipate)diols having molar masses of 1500, 2000 and 3000 were stored at temperatures of 25 and 60°C in the presence of low amounts of different alcohols and some polyurethane (PUR) catalysts, such as dibutyltindilaurate (DBTL), dibutyltindiethoxide (DBTEO), dibutyltinoxide (DBTO), and 1,4-diazabicyclo[2.2.2]octane (DABCO). Alcoholysis was studied using either ethyl acetate (EA) or toluene as solvent. The results were compared with those obtained by examining the behaviour of several dialkyl adipates and ethyl acetate under identical conditions. The alcoholysis in the presence of the tin catalysts proceeds at the same reaction rate without significant decomposition of the catalyst, whereas DABCO is practically inactive. The nucleophilic activity of the alcohols depends on their bulk size rather than their basicity. The resistance of polyalkylene adipates to transesterification increases with the increasing alkyl chain length of diol units in polyester. A partial transesterification of dialkyl adipates takes place too, in spite of ethyl acetate being present in excess.
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  • 11
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    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 179 (1990), S. 157-171 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurde das Permeations- und Trennverhalten von Alkohol/Wasser-Systemen durch poröse PVA-Membranen untersucht. PVA-Membranen mit unterschiedlicher Anzahl und Große von Poren wurden über Mischungen in Lösung mit verschiedenen synthetisierten Polymeren und Copolymeren, wie Polyacrylsäure, Polyacrylnitril, Polyacrylamid, Poly(Methylmethacrylat-co-Maleinsäureanhydrid) etc., anschließendes Gießen von Filmen und Extraktion der Polymeren oder Copolymeren durch Lösungsmittel hergestellt. Die Abhängigkeit der Durchlässigkeit und Trennwirkung von der Größe und Form der permeierenden Moleköle wurde qualitativ diskutiert. Des weiteren wurde die Selektivität der Trennwirkung in Abhangigkeit von der Zusammensetzung von Alkohol/Wasser-Gemischen und von der Größe und Anzahl der Poren untersucht. Es wurde gefunden, daß die Selektivität von der Menge und dem Molekulargewicht der in die Membranen eingebrachten Polymeren abhängt. Wenn der Gewichtsanteil des verwendeten Polymeren größer als 0,1 war, permeierte bevorzugt der Alkoholanteil bei methanolischen Msungen, wobei der Trennfaktor mit steigender Methanolkonzentration anstieg. In Gemischen mit anderen Alkoholen zeigten die Membranen andererseits eine selektive Durchlässigkeit für Wasser. Der Einfluß der Versuchsbedingungen wurde ebenfalls untersucht.
    Notes: The permeation and separation characteristics of alcohol/water systems through porous PVA membranes were investigated. Porous PVA membranes with different pore size and number were prepared by solution blending of PVA with several synthesized polymers or copolymers, such as polyacrylic acid, polyacrylamide, polyacrylonitrile, and methylmethacrylate-co-maleic anhydride, etc. Then casting, and finally extracting the blended polymers or copolymers by solvent from the membranes. The dependency of both permeation and separation on the molecular size and shape of the permeating species was dicussed qualitatively. Moreover, the permselectivity was investigated with attention to the feed composition of alcohol/water mixture and the effect of pore size and number. The selectivity was found to depend on the weight ratio and the molecular weight of polymer introduced to the membrane. When the weight ratio of polymer introduced into the membrane was larger than 0.1, methanol was permeated through membrane preferentially in methanol/water system, and the separation factor increased with increasing the methanol feed concentration. On the other hand, membrane had a selective permeability for water in the other alcohol/water systems. The influence of operating conditions was also studied.
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  • 12
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    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 175 (1990), S. 29-38 
    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 Temperatur des T1-Minimums für die Segmentbewegung in Polypropylen, das einen hohen ataktischen Anteil besitzt, ist niedriger als die in isotaktischem Polypropylen. Ein kurzes T1, T1s, tritt bei beiden Materialien auf. Bei Temperaturerhöhung nimmt T2a (T2 der beweglichen amorphen Bezirke) stark und T2m (T2 der dazwischen liegenden Bezirke) leicht zu, während sich T2c (T2 der steifen kristallinen Bezirke) kaum ändert. T2a in Polypropylen mit hohem ataktischem Anteil ist länger als in isotaktischem Polypropylen.Der Massenbruch der kristallinen Bezirke, Fc, nimmt bei Temperaturerhöhung ab und der der amorphen Bezirke, Fa, zu. Die Relaxationsgeschwindigkeit, 1/ (T1min), steigt linear mit Zunahme des amorphen Anteils an, außer bei der mit siedendem n-Heptan extrahierten Probe. Mit Zunahme der Peaktemperatur von tan δ fällt T2a nahezu linear ab, während die Temperatur des T1-Minimums zunimmt.
    Notes: The temperature of the T1 minimum for the segmental motion in polypropylene containing a lot of atactic fraction is lower than that in isotactic polypropylene. A short T1, T1s, appears for both materials. As the temperature is raised, there is a large increase in T2a (T2 of the mobile amorphous regions), and a mild increase in T2m (T2 of the intermediate regions), while there is no substantial change in T2c (T2 of the rigid crystalline regions). T2a in polypropylene containing a lot of atactic fraction is longer than that in isotactic polypropylene.The mass fraction of crystalline regions, Fc, decreases and that of the amorphous regions, Fa, increases as the temperature is raised. There is a linear increase in the relaxation rate, 1/(T1min), as the amorphous fraction is increased, except for the sample extracted with boiling n-heptane. With increase of the peak temperature of tanδ, T2a decreases nearly linearly, while the temperature of the T1 minimum increases.
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  • 13
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    Angewandte Makromolekulare Chemie 180 (1990), S. 191-198 
    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 Bestrahlung von PTFE mit Elektronen niedriger Energie führt zur Abspaltung von Fluor und zum Einbau von Sauerstoff in die Polymeroberfläche. Es wird gezeigt, daß das Ausmaß der Oberflächenveränderungen hauptsächlich von der Zahl und kaum von der Energie der Elektronen abhängt, die die Oberfläche erreichen. Änderungen in der Oberflächenenergie resultieren in unterschiedlichem Benetzungsverhalten. Kontaktwinkelmessungen und Kurvenanalysen der C-1s-Peaks aus Röntgenphotonenspektroskopiemessungen zeigen, daß der am wenigsten benetzbare Teil der bestrahlten Oberflächen in den meisten Fällen aus —CF2 —CF-Einheiten besteht. Werden bei der Bestrahlung nahezu alle Fluoratome abgespalten, bleiben nur isolierte —CF2-oder —CF-Gruppen zurück. Die „receding“-Winkel werden mit zunehmender Sauerstoffkonzentration in der Oberfläche kleiner, was auf die Bildung stark oxidierter Bereiche hinweist. Die Unabhängigkeit der Kontaktwinkel von der Alterungsdauer deutet auf eine sehr geringe Beweglichkeit der Makromoleküle hin, was mit einer starken Vernet-zung an der Oberfläche zusammenhängen könnte.
    Notes: Low energy electron irradiation of PTFE induced fluorine depletion and introduction of oxygen on the surface. The effect on surface chemistry was shown to be dependent mostly on the amount of electrons reaching the sample, rather than on their energy.Changes in surface energy resulted in different wetting behaviors. The measurement of advancing water contact angles and the analysis of XPS C-1s peak shapes showed that the least wettable portion of irradiated surfaces is made in most cases of —CF2—CF — units. When the treatment caused a nearly complete fluorine depletion, only isolated —CF2— or —CF— groups are present. Receding angle values decreased linearly depending on the amount of oxygen introduced on the sample during the treatment, suggesting the formation of strongly oxidized polymer islets. The invariance of contact angles with aging time indicated very low macromolecular mobility, probably related to extensive surface crosslinking.
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  • 14
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    Angewandte Makromolekulare Chemie 181 (1990), S. 41-52 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In aqueous dispersions of anionic polyurethanes containing the triethylammonium salt of 2,2-dimethylol propionic acid as chain extender, triethylamine can be largely replaced by ammonia. For electrostatic reasons, NH4+ is namely more tightly bound in the ion pairs located in the Stern layer than NH(C2H5)3+. Thermal treatment of films leads to a loss of base, whereby ammonia is more rapidly released than triethylamine. Therefore, crosslinking with partially methylated hexamethylolmelamine proceeds the faster the more triethylamine is replaced by ammonia.
    Notes: In Dispersionen aus anionischen Polyurethanen, die das Triethylammoniumsalz der 2,2-Dimethylolpropionsäure als Kettenverlängerungsmittel enthalten, läßt sich durch Zugabe von Ammoniak eine weitgehende Verdrängung des Triethylamins erreichen. Aus elektrostatischen Gründen ist nämlich in den in der Sternschen Schicht lokalisierten Ionenpaaren NH4+ fester gebunden als NH(C2H5)3+. Bei der thermischen Behandlung der Filme tritt Basenabspaltung ein, dabei erfolgt die Abgabe von Ammoniak deutlich schneller als die von Triethylamin. Die Spannungswerte der mit teilmethyliertem Hexamethylolmelamin vernetzten Proben sind daher um so höher, je mehr Triethylamin durch Ammoniak ersetzt wurde.
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  • 15
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    Angewandte Makromolekulare Chemie 181 (1990), S. 53-66 
    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 Viskoelastizitäts-Parameter von geschmolzenem Polystyrol (PS) wurden mit einem Instron-Kapillarrheometer gemessen.Die Drucknachgiebigkeit B(t) zeigt ein Plateau sowohl im Schmelze (B1)- als auch im Glaszustand (Bg); beide nehmen mit abnehmender Spannung ab. Durch Verschiebung der B(t)-Kurven werden Master-Kurven erhalten, mit denen das Gesamtdruckverhalten (überlagerte elastische und viskose Deformationen) analysiert werden kann. Die stationäre Nachgiebigkeit (Bs) erlaubt eine Beschreibung des elastischen Energieanteils und scheint mit der Extrusions-Strangaufweitung (Bcs/Bds) korreliert zu sein. Die Volumenviskosität (ηk) nimmt mit zunehmender Spannung (P), zunehmender Belastungsgeschwindigkeit (k) und abnehmender Temperatur ab.
    Notes: Viscoelastic parameters of polystyrene (PS) melt in compression creep have been measured in an lnstron capillary-rheometer.Bulk compression creep compliance B(t) shows plateau regions in the molten state (B1) and the glassy state (Bg), both decreasing with increasing stress. Shifting of B(t) curves provides master curves suitable to analysing the total (superposed elastic and viscous deformations) bulk compression behaviour. The steady-state creep compliance (Bs) allows to describe the recoverable elastic energy (Be) and seems to be related to the extrusion die swell (Bcs/Bds). Volume viscosity (ηk) decreases with decreasing stress (P), increasing compression rates (k) and decreasing temperature (T).
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  • 16
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    Angewandte Makromolekulare Chemie 181 (1990), S. 67-74 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurden Untersuchungen über Molekulargewichtsänderungen an physikalisch bei Raumtemperatur gealterten isotaktischen Polypropylenfilamenten (iPP) mit Hilfe der Hochtemperaturgelpermeationschromatographie (HTGPC) durchgeführt. Das Ergebnis der Untersuchungen weist auf eine sehr unbedeutende Änderung des Molekulargewichts des Materials während der Alterung hin.Das Materialgranulat wurde als Bezugsstandard gewählt. Basierend auf der Uneinheitlichkeit D = Mw/Mn des Granulats wurden Filamente der Handelsprodukte GYE 47 und PXC 31399 charakterisiert, deren Alterungsdauer zwischen 2 Wochen und 8 Monaten lag. Bei den Filamenten der Qpe GYE 47 verringerte sich die Breite der Molekulargewichtsverteilung D um durchschnittlich 12%. Andererseits zeigen die Filamente des PXC 31399-vps einen weniger eindeutigen Trend zur Änderung, jedoch im Mittel hat sich die Breite der Verteilung um etwa 20% erniedrigt. Bei letzterem ist die Verteilung iiber die Alterungsdauer stark gestreut. Der GYE 47-Typ zeigt eine nahezu asymptotische Abnahme. Es wird angenommen, daß die Ungleichartigkeit in der Ändenz der Anderung von D zwischen beiden Proben in ihrer unterschiedlichen thermodynamischen Stabilitat liegen ktinnte; PXC 31399 ist weniger stabil.
    Notes: Experiments on the molecular weight variations of physically, room temperature aged isotactic polypropylene (iPP) filaments were done using the High Temperature Gel Permeation Chromatography (HTGPC). Evidence emanating from the studies indicates a very marginal change in molecular weight of the materials during aging.The granules of the materials were chosen as the reference standard. Based on the polydispersity D = Mw/Mn of the granules, filaments of commercial grades GYE 47 and PXC 31399 were characterized between an aging period ranging from 2 weeks to 8 months. The filaments of the GYE 47 grade have their distributions D lowered on the average by about 12%. On the other hand, those of the PXC 31399 grade have a less definite trend in change, but on the average, D is lowered by about 20%. The distributions of this latter grade are highly scattered over the period of aging. The GYE 47 grade shows a reduction in the distribution of a near asymptotic nature. It is believed that the disparity in the trend of change of D between the two samples could be attributed to their relative thermodynamic stability with the PXC 31399 grade being less stable.
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  • 17
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    Angewandte Makromolekulare Chemie 174 (1990), S. 1-10 
    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 Photopolymerisation von Ethylenglykoldimethacrylat (EGDMA) mit Methylmethacrylat (MMA) wurde mit Benzoinmethylether (BME) als Initiator in einem Glasrohr durchgeführt, um einen lichtfokussierenden Plastikstab (Radius Rp) mit parabolischer Brechungsindex-Verteilung (Verteilungskonstante A) in der Nähe der Stabachse (bis zum Radius Rc) herzustellen. Die Abhängigkeit von A und Rc/Rp vom Monomerenverhältnis MMA/EGDMA der Ausgangsmischung, der Einfluß der BME-Konzentration auf die Brechungsindex-Verteilung und die Reproduzierbarkeit der Photopolymerisationen wurden untersucht. Das Rc/Rp-Verhältnis stieg mit dem Monomerenverhältnis MMA/EGDMA bei BME = 1,0 Gew.-% und der Geschwindigkeit der UV-Lampe von V = 0,58 mm/min an. Andererseits stieg Rc/Rp bei BME = 0,6 Gew.-% und V = 0,735 mm/min bis zum Monomerenverhältnis von 0,2 an und fiel dann deutlich zwischen 0,20 und 0,25 ab. Die Plastikstäbe, die hier durch Photopolymerisation hergestellt wurden, haben Linseneigenschaften und sind gut reproduzierbar.
    Notes: The photocopolymerization of ethyleneglycol dimethacrylate (EGDMA) with methylmethacrylate (MMA) containing benzoin methyl ether (BME) as initiator was carried out in a glass tube to fabricate a light-focusing plastic rod (radius Rp) with a parabolic refractive index distribution (distribution constant A) in the region near the center axis (radius Rc). The dependence of A and Rc/Rp on MMA/EGDMA feed ratio, influence of BME concentration on the refractive index distribution, and the reproducibilities of the photopolymerizations were investigated. The Rc/Rp increased with the feed ratio used under BME = 1.0 wt.-% at velocity of UV lamp V = 0.58 mm/min. On the other hand, Rc/Rp increased with the feed ratio to 0.2 and then decreased remarkably with the feed ratio in the range of 0.2-0.25 with BME = 0.6 wt.-% at V = 0.735 mm/min. Plastic rods fabricated in the investigation using photopolymerization have lens characteristics and good reproducibilities.
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  • 18
    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: Polystyrol- und Polymethylmethacrylateinzelfäden mit verschiedenen Graden von Doppelbrechung wurden durch die kontinuierliche Änderung der Ziehgeschwindigkeit, der Temperatur der Polymerschmelze und des Molekulargewichts von Polystyrol (PS) und Polymethylmethacrylat (PMMA) gewonnen. Der “brittle to ductile” Übergangspunkt (Übergang des Polymeren vom spröden zum ziehbaren Zustand) wurde für das optisch reine Polystyrol im Bereich der Doppelbrechungszahlen -0,6 · 10-3 bis -2,6 · 10-3 gefunden. Höhe und Lage dieses Punktes werden durch das Molekulargewicht, die Molekulargewichtsverteilung und die Temperatur der Polymerschmelze beeinflußt. Die Werte des Doppelbrechungsindexes von PS sind um zwei Zehnerpotenzen höher als von PMMA. Bei PMMA wurde der “brittle to ductile” Übergangspunkt nicht beobachtet. Die mechanischen und optischen Eigenschaften hängen nicht nur vom mittleren Wert des durch die Doppelbrechung charakteri-sierten Orientierungsgrades ab, sondern auch davon, welcher Teil des Relaxations-spektrums des Polymeren vorzugsweise orientiert ist. Beim Ziehen der PS- und PMMA-Einzelfäden bilden sich in der Mitte des Fadens Risse (crazes), die jedoch nicht an die Oberflache des Fadens treten.
    Notes: Monofilaments possessing various degrees of birefringence were obtained by changing the drawing rate, the molten polymer temperature, and the molecular weight of polystyrene (PS) and poly(methyl methacrylate) (PMMA). The “brittle-toductile” transition point of optically pure PS was found in the range of birefringences of -0.6 · 10-3 to -2.6 · 10-3. Both the height and position of this point are influenced by M̄w, molecular weight distribution, and polymer melt temperature. The birefringence of PS is higher by two orders of magnitude than that of PMMA in which this transition point has not been observed. The mechanical and optical properties depend not only on the average amount of orientation characterized by the birefringence but on what portion of the relaxation spectrum of the polymer is preferentially oriented. During the drawing of PS and PMMA monofilaments crazes are formed in the centre of the fibers and do not reach the surface.
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  • 19
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 174 (1990), S. 105-117 
    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 possibility of the application of atactic polypropylene is investigated as graft base for the preparation of graft copolymers of vinyl acetate and vinyl chloride respectively graft copolymers from vinyl acetate onto polypropylene as graft base for the preparation of graft copolymers of vinyl chloride in relation to the composition of the original mixture.After compounding of the graft products with polyvinyl chloride or ABS/polyvinyl-chloride mixtures selected mechanical properties are presented in relation to the quantity and composition of the incorporated graft copolymers.
    Notes: Die Möglichkeiten des Einsatzes von ataktischem Polypropylen als Pfropfgrundlage zur Herstellung von Pfropfcopolymerisaten des Vinylacetates und Vinylchlorids bzw. von Polypropylen-Vinylacetat-Pfropfprodukten als Pfropfgrundlage zur Herstellung von Pfropfcopolymerisaten des Vinylchlorids werden in Abhängigkeit von der Ausgangsgemischzusammensetzung untersucht.Nach Abmischung der Pfropfprodukte mit Polyvinylchlorid bzw. ABS/Polyvinylchlorid-Mischungen werden ausgewählte mechanische Eigenschaften sowohl in Abhängigkeit von der Menge des enthaltenen Pfropfproduktes als auch von der Zusammensetzung der Pfropfpolymerisate dargestellt.
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  • 20
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: A new spectroscopic method for determining the permeability of ammonia in transparent polymer layers is presented. It is based on the quantitative proof of the ammonia passing the test layer into a sensor layer, containing 4-nitrophenol as an NH3-sensitive probe, which is placed under the test film. The permeability (P) of the test layer is calculated from the slope of extinction with time in the sensor layer. The lag time (t1) gives the diffusion coefficient (D). The suitability of this method is confirmed by comparison with literature values. Diffusion coefficients obtained from t1 correspond well to those obtained by the sorption method.The temperature dependence of P and D in more than five different polymers (CDA, PVB, PVAc, PVC and different polyvinyl alcohols) demonstrates that peculiarities in the temperature dependence of the permeability result from the behaviour of the NH3-solubility (P/D) which is strongly dependent on the polymer structure.
    Notes: Es wird eine neuartige spektroskopische Methode zur Messung der Ammoniak-Permeabilität in transparenten Polymerfilmen vorgestellt. Sie beruht auf dem quantitativen Nachweis des den Testfilm durchdringenden Ammoniaks in einer darunter befindlichen Sensorschicht mit Hilfe der NH3-empfindlichen Sonde 4-Nitrophenol. Aus dem Anstieg der Extinktion mit der Zeit (ΔE/Δt) in der Sensorschicht wird die Permeabilität (P) und aus der Verzögerungszeit (lag time (t1)) der Diffusionskoeffizient (D) berechnet. Die Eignung der Methode wird durch Vergleich mit Literaturwerten belegt. Die aus t1 zugänglichen Diffusionskoeffizienten stimmen sehr gut mit denen überein, die mit der Sorptionsmethode gefunden werden.Die Temperaturabhängigkeiten von P und D in mehr als fünf verschiedenen Polymeren (CDA, PVB, PVAc, PVC und in verschiedenen Polyvinylalkoholen) zeigen, daß Besonderheiten im Temperaturgang der Permeabilität aus dem vom Aufbau des Polymeren stark abhängigen Verhalten der NH3-Löslichkeit (P/D) resultieren.
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  • 21
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 179 (1990), S. 99-111 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurde die strahleninduzierte Pfropfung von 4-Vinylpyridin (VP) auf Styrol-Butadien-Styrol-Copolymere (SBS) in Gegenwart von gelöstem Sauerstoff untersucht. Pfropfcopolymer-Membranen mit unterschiedlichen Pfropfgraden wurden durch Gießen aus benzolischer Lösung hergestellt. Die mechanischen Eigenschaften, die Gaspermeabilität sowie der Einfluß der Temperatur auf die Gasdurchlässigkeit wurden untersucht. Der höchste Pfropfgrad von 8,4% wurde bei einer Bestrahlungszeit von 15,5 herreicht. Sowohl bei kürzeren als auch längeren Bestrahlungszeiten war der Pfropfgrad  -  bedingt durch Störung durch den vorhandenen Sauerstoff  -  niedriger. Reißfestigkeit und Reißdehnung von SBS-g-VP waren vergleichbar rnit SBS. Die Spannungsrelaxation von SBS-g-VP war langsamer als bei SBS, was auf der Bildung von starren Polyvinylpyridin(DVP)-Mikrophasen beruhen könnte, die als permanente Vernetzungspunkte wirken und die Spannungsrelaxation beeinträchtigen könnten.Da SBS eine hohe Gasdurchlässigkeit und PVP eine hohe O2/N2-Selektivität aufweisen, wurde die Gasdurchlässigkeit der Pfropfmembranen untersucht. Die Selektivitat der SBS-g-VP-Membranen stieg mit steigendem Pfropfgrad, allerdings auf Kosten der Permeabilität, Bei Erhöhung der Temperatur nahm die Durchlässigkeit zu, das Verhältnis O2/N2, aber ab. Die Aktivierungsenergie (Ep) der Gasdurchlässigkeit stieg mit dem Pfropfgrad. Für eine nichtgepfropfte SBS-Membran betrug Ep 5,5 kcal/mol für Sauerstoff und 7,2 kcal/mol für Stickstoff. Für eine SBS-g-VP-Membran mit einem Pfropfgrad von 8,4% waren die Ep-Werte für Sauerstoff und Stickstoff 6,5 bzw. 8,1 kcal/mol.
    Notes: The grafting of 4-vinyl pyridine (VP) onto styrene-butadiene-styrene triblock copolymers (SBS) by homografting irradiation with dissolved oxygen was studied. Homograft membranes of various degree of grafting were prepared from a casting solution of grafted copolymer in benzene. The mechanical properties of membranes, gas permeability, and the effect of operating temperature on gas permeation were investigated.The degree of grafting of 8.4% was the largest at an irradiation time of about 15.5 h. It was smaller at both shorter and longer duration because of the interference of dissolved oxygen. It was found that the tensile strength and elongation of SBS-g-VP were similar to those of SBS. The stress relaxation of SBS-g-VP was slower than that of SBS, and this might be due to the formation of rigid microphase separation domain of poly(4-vinyl pyridine), which acted as permanent crosslinking points to reduce the stress relaxation.Using the properties of high flux of SBS and high O2/N2 selectivity of poly(4-vinyl pyridine), the performance of gas permeation of 4-vinyl pyridine homografted SBS membrane was studied. The selectivity of SBS-g-VP membrane increased with increasing degree of grafting. However, it was done at the expense of a decrease in the gas permeability.When the operating temperature of gas permeation increased, the permeability of oxygen and nitrogen increased, and the O2/N2 permeability ratio decreased. The activation energy (Ep) for gas permeation through different degree of grafting of SBS-g-VP membrane (obtained by the Arrhenius law) increased with increasing degree of grafting. For ungrafted SBS membrane, Ep was 5.5 kcal/mol for oxygen and 7.2 kcal/mol for nitrogen. For 8.4% grafting degree SBS-g-VP membrane, Ep for oxygen and nitrogen, were 6.5 and 8.1 kcal/mol, respectively.
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  • 22
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 175 (1990), S. 13-27 
    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 change of molecular mass and long-term strength of high and low density polyethylene under tensile load in surface-active medium was studied. It is shown that long-term strength of polyethylene depends on the molecular mass. The influence of polydispersity on strength was investigated.
    Notes: Es wird über die Untersuchungsergebnisse von Lebensdauer und Molmassenänderung an polydispersen Proben von HDPE und HDPE in einem breiten M̄v-Bereich im Zugversuch in einem oberflächenaktiven Medium berichtet.Die Arbeit enthält auch die Darstellung der quantitativen Änderung der Molmasse von Hochdruck- und Niederdruck-Polyethylen unter Dauerbeanspruchung und die Analyse der Lebensdauer in Abhängigkeit von den unterschiedlichen Molmassen (MM) (M̄w, M̄n, M̄v); die Unterschiede in Abhängigkeit von der Lebensdauer von M̄v für Proben und polydisperse Muster sowie die Vorstellungen über den dualen Einfluß der Polydispersität auf die Lebensdauer mit einer Interpretation der auftretenden Erscheinungen werden beschrieben.
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  • 23
    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: One constitutive property for the description of dyeing polyester-materials with disperse dyes is the particle size distribution in the dye bath. To measure particle sizes below one micrometer in situ, special techniques are required. One of these is the so called photon-correlation-spectroscopy, depending on the scattering of laser light by suspended small particles in a fluid. The mathematical and physical principles of the photon-correlation-technique are explained in this article.
    Notes: Eine zur Beschreibung des Färbevorganges von Polyestermaterialien mit Dispersionsfarbstoffen wesentliche Größe stellt die Partikelgrößenverteilung im Farbebad dar. Partikelgrößen unterhalb eines Mikrometers lassen sich in situ nur mit wenigen Meßtechniken bestimmen. Dazu zählt u. a. die Photonen-Korrelations-Spektroskopie, die auf Streuung von Laserlicht an kleinen, in einer Flüssigkeit suspendierten Teilchen basiert. Die mathematischen und physikalischen Grundlagen dieser Meßtechnik werden in diesem Artikel erläutert.
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  • 24
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 175 (1990), S. 81-97 
    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 Kristallinität von Polyethylen, Polyethylenterephthalat und Polypropylen wurde mit Hilfe der Röntgenweitwinkel(WAXS)-und-kleinwinkel(SAXS)streuung gemessen. Die mittels der letzteren Methode erhaltenen Kristallinitätswerte sind deutlich größer als die durch WAXS. Es wird vermutet, daß die Unterschiede mit der Schicht zusammenhängen, die zwischen den amorphen und kristallinen Bereichen liegt. Daraus wurde geschlossen, daß die Röntgenkleinwinkelstreuung nicht als unabhängige Routinemethode zur Kristallinitätsbestimmung angewendet werden kann.
    Notes: The crystallinity of polyethylene, polyethyleneterephthalate, and polypropylene was measured with the aid of wide angle (WAXS) and small angle (SAXS) X-ray scattering methods. The values of crystallinity evaluated using the latter method are distinctly larger than those ones given by the WAXS method. The differences are supposed to be associated with the transition layer existing between the amorphous and crystalline regions. It was concluded that small angle X-ray scattering cannot be employed as an independent routine method of crystallinity determination.
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  • 25
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 175 (1990), S. 117-128 
    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: Für das System Cellulosenitrat-μ-Styragel-THF wurde die DP-Ve-Beziehung sowie die Ausarbeitung der betreffenden Eichparameter einer genaueren Betrachtung unterzogen. Die etwa dreißig Eichpräparate waren durch definierten säurekatalysierten Abbau von Baumwollcellulose und anschließende Nitrierung hergestellt worden und umfaßten einen DP-Bereich von 150 〈 DP 〈 8000. Es wird gezeigt, daß mit steigendem DP die DP-Ve-Beziehung drei verschiedene Phasen aufweist. Bei der Anwendung der SEC auf Cellulosenitrat müssen daher bezüglich der Eichung zwei Fehlerquellen in Betracht gezogen werden: eine bezieht sich auf die Methode der Ausarbeitung der Eichparameter als solche, und die andere auf die Nichtbeachtung des Vorhandenseins dreier Abschnitte in der DP-Ve-Beziehung. Die Auswirkung dieser Fehler auf die Genauigkeit der aus den Elutionsdiagrammen abgeleiteten Verteilungskurven und DP-Mittelwerte wird diskutiert.
    Notes: The calibration behaviour of the system cellulose nitrate-μ-Styragel-THF has been studied using about 30 different calibration samples prepared by defined acid catalyzed degradation of cotton cellulose. The samples covered a range of DP between 150 〈 DP 〈 8000. It is shown that the DP-Ve relationship is characterized by the existence of three subsequent stages. Consequently, two sources of errors in the DP-Ve calibration must be taken into consideration. One refers to the methods as such to elaborate the calibration parameters, and the other one arises by neglecting that the DP-Ve relationship involves 3 distinct stages. The extent of the two classes of errors in regard to the exactness of the determined molecular weight averages and molecular weight distributions is discussed.
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  • 26
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 175 (1990), S. 141-156 
    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: Bei der Polycondensation von d,l-Asparaginsäure mit Nδ-phthaloyl-L-ornithin in Phosphorsäure bei 185°C entstehen statisticsche Copolymere (Ausbeute 60  -  70%) aus Poly(d,l-succinimid-co-Nδ-phthaloyl-d,l-ornithin), Formel 6, mit inhärenten Viskositäten (DMF) von 5 bis 15 ml g-1. Copolyimide der selben Zusammensetzung 6 und vergleichbarer Kettenlänge werden aus Asparaginsäure und dem Kupferchelat des Phthaloylornithins erhalten. Die Behandlung des Copolymeren 6 mit Hydrazinhydrat fuhrt zur Öffnung der Succinimid-Kettenglieder unter Bildung von Hydrazid-Seitengruppen. Die resultierenden Polyamide sind Poly(α,β-d,l-asparaginsäurehydrazid-co-d,l-ornithin), Formel 7. Kürzere Reaktionszeiten bedingen unvollständige Ringöffnung, und die verbleibenden Succinimid-Gruppen werden bei der folgenden Aufarbeitung hydrolytisch gespalten unter Bildung von Asparaginsaüre-Gruppen; die sogebildeten Polyamide besitzen die Struktur 8. Beide Polymere, 7 und 8, sind in Wasser loslich und zeigen in Wasser inharente Viskositiiten von 5 bis 14 ml g-l. Die Fahigkeit dieser Polyamide zur Arzneimittelverankerung wird durch Ankoppeln von Carbonsau- ren als Modellsubstanzen gezeigt.
    Notes: The polycondensation of d,l-aspartic acid with Nδ-phthaloyl-l-ornithine in phosphoric acid at 185°C gives rise to the formation, in 60  -  75% yield, of random copolymers of the poly(d,l-succinimide-co-Nδ-phthaloyl-D,L-ornithine) type 6 possessing inherent viscosities (DMF) in the range of 5  -  15 ml g-1. Copolyimides of the same compositions 6 and comparable chain lengths are obtained from aspartic acid and the copper chelate of the phthaloylornithine. Treatment of copolymers 6 with hydrazine hydrate in DMF leads to N-deprotection and opening of the intrachain succinimide rings with formation of hydrazide side groups. The resultant polyamides are of the poly(α,β-d,l-asparthydrazide-co-d,l-ornithine) type 7. Shorter reaction periods give incomplete hydrazinolytic ring opening, and the remaining succinimide units are cleaved hydrolytically during the subsequent aqueous workup, thereby transforming into aspartic acid units. The polyamides so formed possess the general poly(α,β-d,l-asparthydrazide-co-α,β-d,l-aspartic acid-co-d,l-ornithine) structure 8 Both types 7 and 8 are soluble in water and, in this medium, give inherent viscosities of 5  -  14 ml g-1. The potential drug-anchoring capabilities of these amine-functionalized polyamides are demonstrated by coupling reactions with model carboxylic acids.
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  • 27
    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: Im Zusammenhang mit Arbeiten über den Wirkungsmechanismus von Antioxidantien in Kohlenwasserstoffpolymeren unter Sauerstoffmangel wurde die Abfangreaktion des Modellradikals 1-Cyano-1-methylethyl (R°) mit N-Isopropyl-N′-phenyl-1,4-phenylendiamin (Ia) und seinem Oxidationsprodukt IIa untersucht. Reines Ia und IIa reagieren kaum mit R′, eine Mischung aus beiden ist jedoch ein effektiver Fänger fur R′, wobei R′ entweder am Stickstoffatom zwischen den aromatischen Ringen unter Bildung von VIa gebunden wird, oder unter Substitution mit dem Phenylenring reagiert, wobei VIIIa entsteht. Verbindung VIa ist labil, bei Vulkanisationstemperatur spaltet sie im neutralen Medium Olefin unter Regenerierung von Ia ab. In Gegenwart von Säuren lauft diese Reaktion auch bei niedrigerer Temperatur ab. Im Produkt VIIIa ist R′ fest gebunden, durch die Nitrilgruppe tritt jedoch eine säurekatalysierte Cyclisierung zum Indolinderivat X ein. Die Bildung von VIIIa ist ein Modell für die Entstehung einer „nichtextrahierbaren Fraktion“ des Antioxidants Ia bei der Stabilisierung von Kohlenwasserstoffpolymeren.
    Notes: In connection with the investigation of the mechanism of antioxidant action of antidegradants in hydrocarbon polymers under the conditions of a relative deficiency of oxygen, scavenging of a model alkyl (1-cyano-1-methylethyl,R°) was studied with Nisopropyl-N′-phenyl-1,4-phenylenediamine (Ia)For abbreviations see p. 11. and its oxidation product, i.e. Nisopropyl-N′-phenyl-1,4-benzoquinonediimine (IIa). While pure Ia and IIa do not react with the radical R° almost at all, their mixture is able to scavenge R° effectively. The reaction is further accelerated with acids. The alkyl R° combines with the antidegradant molecule in two ways, one of which leads to the substitution at the nitrogen atom between the aromatic rings, giving rise to VIa, while the other consists in the substitution of phenylene, leading to VIIIa. The product VIa is labile, and at vulcanization temperatures it readily splits off olefin in a neutral medium, being regenerated to Ia. In the presence of acids this reaction proceeds even at lower temperatures. In the other product, i.e. in VIIIa, the alkyl R° is bound firmly, but due to the presence of the nitrile group, VIIIa is readily cyclized by the effect of acids, and an indoline derivative X is formed. The formation of VIIIa is a model of the formation of an “unextractable fraction” of antidegradant Ia in the stabilization of hydrocarbon polymers. Investigations based on the isolation of reaction products bear at the same time evidence of the possibility of regeneration of an effective antioxidant in the stabilized substrate.
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  • 28
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The photochemical degradation of polymers (commonly known as UV degradation) takes place in two stages: First, there is the primary process comprising the rapid formation of radicals caused by quanta of visible light; this involves the dissociation of polymer chain molecules and/or the activation of polymer chain molecules respectively of additives, colorants and impurities contained in the polymer. The secondary process consists in oxidation reactions with singulett-oxygen generated by energy-transfer and/or between the polymer radicals thus formed and adsorbed oxygen, as a result of which gradual degradation of the polymer takes place.An investigation of these individual reactions using a combination of selected physical test methods leads to an unterstanding of the entire reaction sequence involved in photo-oxidative degradation. This knowledge provides a basis for systematically improving the weather-resistance of polymers by modifying their basic polymeric structure or through the controlled use of UV absorbers, quenchers, radical interceptors and antioxidants.The physical test methods themselves are divided into two categories: techniques used for investigating the primary processes (ultra short-time spectroscopy, ESR) and those used to investigate the secondary processes (XPS, FT-IR, UV/VIS et al.).With pigmented polymers, attention is focussed on borderline cases in the use of photoactive and photoinactive pigments: as a result of “photocatalytic oxidation”, photoactive pigments (e.g. TiO2 anatase) lead to additional degradation reactions which take place at the same time as the UV degradation reaction. Photoinactive pigments (e.g. high-grade TiO2-rutile and iron oxide pigments), on the other hand, exhibit negligible or no photocatalytic oxidation and, by absorbing UV radiation, provides better protection for the polymer against UV degradation.This paper gives an overview of the above-mentioned physical methods of investigating primary and secondary photochemical processes, taking a thermoplastic material (Polycarbonate) as an example. A description is also given of the photocatalytic oxidation reations which can take place if pigmented polymers are used, and there is a discussion of the degradation-inhibiting effects of inorganic pigments.
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  • 29
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The aim of the present work is to predict the warehouse storage life of polyethylene low-density, polyethylene high-density and polystyrene impact-resistent, using the method of temperature-time superposition. The properties, most representative for thermal ageing, are the relative elongation at break for polyethylene and the impact resistance for polystyrene. The validity of the predicted shelf-life is verified by estimating the change of these properties under real conditions of warehouse storage.
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  • 30
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A commercial type of impact-resistant polystyrene was investigated. Two types of antioxidants, Irganox 245 and Irganox PS-800 were added to polystyrene in ammounts of 0,05 to 0.20%. Films, dumbbells and straight test pieces were subjected to thermal and u.v. ageing. Films of 250 μ thickness were thermally treated at 100°C and separately u.v. irradiated at 360 nm for 24, 72, 120 and 168 hours. Dumbbells and straight test pieces were only thermally aged at 100°C for 7, 14, 21, 28 and 35 days. Mechanical properties were determined. The spectra of samples were recorded using Perkin-Elmer, model 1750 FTIR and Perkin-Elmer data station 7700. Colour changes of all dumbbells were measured using Elrepho apparatus in u.v.-visible region. (Changes of the content of carbonyl and hydroxyl groups, as well as of polybutadiene (PB) unsaturation in films were recorded on i.r. spektrophotometer Perkin-Elmer 257 between 4000 and 625 cm-1 and were published in the first part of this study1).
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  • 31
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    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 181 (1990), S. 85-91 
    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: Formstoffe aus aromatischen Polyepoxiden, aromatischen Polyaminen mit hochtemperaturbeständigen Strukturelementen sowie pulverförmigen Füllstoffen besitzen hervorragende Eigenschaften, wie hohe Glasübergangstemperatur, hohemechanische Festigkeit, kleinen thermischen Ausdehnungskoeffizienten und Schwerbrennbarkeit ohne Zugabe von Flammschutzmitteln. Über die Synthese dieser aromatischen Polyamine, die Herstellung und Verarbeitung der Niederdruckpreßmassen sowie die Eigenschaften der Formstoffe wird berichtet.
    Notes: Moulded materials produced from aromatic epoxide resins, aromatic polyamines with high-temperature-resistant structure units and powdered mineral fillers possess outstanding properties like high glass transition temperatures, high mechanical strength, low linear thermal expansion coefficient, and reduced flammability without the addition of flame retardants. An account is given of the synthesis of aromatic polyamines, the preparation and working of moulding materials and the properties of the finished products.
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  • 32
    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 influence of linearly and circularly polarized light on the state of order of nematic dye-copolymers is investigated. For a nematic model system we have shown that the optical axis of these systems can be reorientated with linearly polarized light in a well defined manner. Furthermore these investigations prove that the isomerisation cycles of the azo dye is responsible for the described properties. By selection of circularly polarized light the same transmission behaviour as shown by selectively reflecting materials, i. e. cholesteric liquid crystals, was observed.
    Notes: Untersucht wird der Einfluß von linear und zirkular polarisiertem Licht auf den Ordnungszustand von nematischen Farbstoff- Copolymeren. Am Beispiel eines Modellsystems wird gezeigt, daß mit linear polarisiertem Licht die optische Vorzugsachse dieser Systeme gezielt reorientiert werden kann. Die Untersuchungen zeigen, daß der Isomerisierungszyklus des Azofarbstoffes für diese Eigenschaft des Materials verantwortlich ist Nach Bestrahlen der Probe mit zirkular polarisiertem Licht wird für das Polymere das gleiche Transmissionsverhalten beobachtet. Wie es auch selektivreflektierende Materialien, z. B. cholesterische Flüssigkristalle, aufweisen.
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  • 33
    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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  • 34
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: For fabricating microstructures with extreme structural heights a technology has been developed which is based on deep-etch lithography and subsequent replication processes. A particularly high precision is achieved if the lithographic process is carried out by means of synchrotron radiation. Electroforming and molding processes are used for the replication of microstructures from a large variety of materials. The field of application comprises micromechanics, microoptics, electrical and optical microconnectors as well as sensors and actuators.
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  • 35
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 5 Ill.
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  • 36
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Charge carrier transport properties of organic polymers can vary over a wide range. The paper shows that the electron- and hole mobilities of polymers with pendant photoconductive groups (i. e. carbazole) are on the order of 10-6 cm2/Vs. In these materials the flow of electronic charge is maintained by the overlap of the π-orbitals of the pendant molecular groups. The large variation of this short-range interaction, depending on the local configurations encountered in polymer glasses, leads to a large variation of hopping probabilities and, hence, to wide rate-distributions. These distributions are reflected in the slow algebraic decay characteristics of the observed photocurrents. The typical time exponents α (α 〈 1) are shown to carry a great deal of physical information, if the dynamical range of the experiments is sufficiently large. The paper also refers to quasi-conjugated polymers (polysilanes) whose dynamic transport parameters are about 103 times better (faster) as compared to polymers with pendant groups. These new materials open interesting aspects for the development of new polymeric materials with better transport parameters and, hence, shorter 'switching times'.
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  • 37
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    Angewandte Makromolekulare Chemie 174 (1990), S. 69-80 
    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: It is shown, that hydroxyterminated polydienes of good microstructure and functionality and a narrow molecular weight distribution can be prepared using di-hydroxyethyl-azo-bis-isobutyramide as an initiator. The activation energy of the initiator decay has been determined by volumetric measurement of the nitrogen evolved in this reaction.
    Notes: Es wird gezeigt, daß hydroxyterminierte Polydiene mit guter Mikrostruktur und Funktionalität sowie enger Molekulargewichtsverteilung unter Verwendung von Azobis-isobuttersäure-di-hydroxyethylamid hergestellt werden können. Die Aktivierungsenergie des Initiatorzerfalls wurde durch volumetrische Messung des bei dieser Reaktion freiwerdenden Strickstoffs bestimmt.
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  • 38
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    Angewandte Makromolekulare Chemie 174 (1990), S. 81-88 
    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 Reaktion von Bisphenol A-diglycidether (BADGE) mit Butan-1,4-diol (BD) in Gegenwart von Mg(ClO4)2 führt in Abhängigkeit von der Reaktionstemperatur zu linearen und verzweigten Oligomeren. Bei 100°C Reaktionstemperatur läßt sich die Produktbildung bis ca. 70% Epoxid-Umsatz durch HPLC feststellen. In diesem Umsatzbereich sind alle Produkte gut in THF löslich, woudurch die Verfolgung des Molmassenanstieges mittels SEC möglich ist. Es wird eine charakteristische Molmasse-Umsatz-Beziehung erhalten sowie die SEC-Daten eines verzweigten Produktes diskutiert.
    Notes: The reaction of bisphenol A-diglycidyl ether (BADGE) with butane-1,4-diol (BD) in the presence of Mg(ClO4)2 leads to linear and branched oligomers. The formation ratio of these products depends on the reaction temperature. In experiments at 100°C, an epoxide consumption of up to 70% can be observed using HPLC. In this range all products show good solubility in THF, so that it is possible to follow the increasing molar mass by using SEC. A characteristic relation of the molar mass against the conversion rate is derived and SEC data of a branched product are discussed.
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  • 39
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thermal and photodegradation of copolymer system based on styrene, butyl acrylate, acrylic acid and N-methylolacrylamide (S/BA/AA/MAA) shows mechanical, but no structural changes in examined temperature range and after 320 h of UV irradiation (simultaneously with 256 and 366 nm lamps). Content of acrylic acid is a very important factor for the mechanical stability of these systems which can be very successfully used as the coatings in the practice. Found correlations indicate mechanism and factors having influence on the excellent stability of copolymer films.
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  • 40
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The influence of light wavelength and intensity, as well as the temperature, on photooxidation has been studied for rubbers based on polydieneurethane (PDU) or polyetherurethane (PEU). Photooxidation is shown to proceed by the chain free-radical mechanism with bimolecular (for PDU) or linear (for PEU) kinetic chain termination. The PDU oxidation kinetic parameter is equal to 0.02 [mole/(kg·s)]1/2 and does not depend on temperature. In PEU photooxidation the kinetic chain length is constant in a wide range of light intensities and is equal to 7, while the activation energy is ca 18 kJ/mole. In distinction to PEU, PDU is sensitive not only to UV but also to visible light, with this sensitivity being preserved up to high oxidation levels. The dependences of photooxidation quantum yieldes on wavelength and irradiation time have been determined.
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  • 41
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Three types of transparent PVC-films before and after exposition in the weather conditions are studied. The first film (the control) is plasticized and stabilized; the second is similar to the first but 1 part of cuprous oxide (CuzO) is incorporated in it, while in the third 1 part of aluminium (A1) powder is added. It is found that the light transparency decreases by 2-7% upon adding Cu2O and by 17-36% upon adding Al-powder. UV-visible measurements, colourimetric measurements and microscopic investigations are used for examining PVC-samples properties during weathering. The surface layer chemical changes are studied by means of MIR-IR-spectroscopy. The total colour variation (ΔE*ab) in the case of 12 months aged PVC-film, containing Cu2O, shows 11 relative units in comparison with 37 relative units for the other two materials. A retarding action of Cu2O and an accelerated effect of Al-powder on the weather degradation of clear soft PVC-films are established. The influence of the chemical properties and different size distribution of the dispersive additives on photooxidative behaviour of PVC-compositions are discussed.
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  • 42
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The response of a HDPE, a L-LDPE and a PP homopolymer to processing conditions and processing stabilizer formulations in the 220°C to 280°C temperature range was investigated. The technique of multiple extrusion was used. Melt flow and melt flow ratio were measured after the first, third and fifth extrusion pass. In the case of the HDPE and the L-LDPE, degradation by cross-linking was the predominant reaction and the molecular weight distribution showed a significant broadening compared to the virgin samples. The PP homopolymer degraded by chain scission. By adding a multifunctional hindered phenol and a hydrolysis resistant phosphite, all polymers could be efficiently protected against degradation on processing. For the HDPE and the L-LDPE, increased amounts of phosphite provided increased processing stability at constant phenol concentration. A 4:1 ratio of phosphite to phenol exhibited the best performance. The most efficient ratio for protecting melt flow of the PP homopolymer was found when a two to one ratio of phosphite to phenol was added.
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  • 43
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The HALS stabilization mechanisms usually envisaged do not explain the experimental facts. New mechanisms are proposed instead. They include quenching of excited charge-transfer complexes (CTC) polymer-oxygen by CTC HALS-oxygen. In addition, the formation of CTC between peroxy radicals and NH-HALS is of prime importance. These CTC HALS-peroxy radicals can either react photolytically after absorption of UV radiation or with a second peroxy radical, thus promoting termination between two peroxy radicals.Initiation of photooxidation in HALS stabilized polyethylene involves usually CTC HALS-oxygen throughout the useful lifetime of the polymer. In contrast to that, initiation of photooxidation in HALS stabilized polypropylene is classical and due to photolysis of tertiary hydroperoxides.The formal kinetics based on the mechanisms envisaged explain the experimental results observed with HALS stabilized polyethylene and polypropylene. On the one hand, they concern, the performance of HALS: in polyethylene it is a linear function of the square root of HALS concentration whereas in polypropylene it increases linearly with HALS concentration as long as the last does not become too high. On the other hand, the experimental facts explained, concern the decrease of the HALS concentration during W exposure of HALS-stabilized polyethylene and polypropylene. The decrease is first order in both polymers but is independent of the initial HALS concentration in polyethylene, whereas it decreases with increasing initial HALS concentration in polypropylene. This is in agreement with the corresponding initiation mechanisms envisaged for polyethylene and polypropylene.
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  • 44
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Our experiments have shown that after a complex degradative effect, such as processing, irradiation and ageing, the effects of antioxidants and their mixtures are very different.The results of our investigation support the opinion, expressed by many researchers of stabilization, that there does not exist any universally practicable antioxidative system. The optimal effect has to be determined, for each system, in the knowledge of the quality and quantity of the given oxidative load.For polyethylene crosslinked by irradiation a satisfactory stability can be attained with the aid of the usual stabilizers; however, they must be used in relatively larger quantities owing to the additional degradative action of the irradiation. There are noticeable differences between the stabilizers not only in their stabilizing action, but also in influencing the degree of discoloration and in the dose number required to produce the same degree of crosslinking.
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  • 45
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A brief introduction describes the main differences between homo, and copolymer polyacetals and their main degradation mechanisms. A short overview describes the importance of stabilization and the necessity of using antioxidants and costabilizers during manufacturing, processing and end use of polyoxymethylene(polyacetals). Various stabilizer systems are presented and studies on the interaction of antioxidants with costabilizers added. The criteria for testing the performance of these additives are discussed and demonstrated by many examples.In a second part the increasing importance of light stabilized polyacetal is mentioned and investigations on the performance of light stabilizer systems are highlighted.
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  • 46
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Quinone imines are formed from aromatic amine antidegradants as a consequence of chemical transformations of the latter during the stabilization of hydrocarbon polymers. Quinone imines are deep coloured compounds and contribute to the antidegradant activity of the parent amines. The main interest is devoted to benzoquinone diimines (BQDI), generated from N,N '-disubstituted 1,4-phenylenediamines (PD). BQDI are antioxidants in unsaturated hydrocarbons, undergo hydrolytic deamination, addition and cyclization reactions, react with 2,6-dialkylphenols, thiols and C-centered radicals. PD are regenerated from BQDI in redox reactions. The active role of BQDI in antifatigue processes in rubbers has been explained using product analysis. BQDI account for staining and discoloring properties of PD but are not harmful to the polymer stability.
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  • 47
    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: As a first step to analyse the particle size distribution of dyebaths, photoncorrelation-spectroscopy is used to determine the particle sizes of latex suspensions. To simulate the procedure of dyeing polyester fibres with disperse dyes, latex suspensions are used as model for dyes. The ‘dyeing’ is carried out at various temperatures and the resulting particle size distribution of the ‘dyebath’ is measured using photon-correlation-spectroscopy.
    Notes: Als Vorstufe zur Teilchengrößenanalyse von Farbstoffbädern mittels Photonen-Korrelations-Spektroskopie werden Latexsuspensionen untersucht. Eine Simulation einer Färbung von Polyestermaterial mit Dispersionsfarbstoffen wird durch eine ‘Modellblindfärbung’ unter Benutzung von Latexsuspensionen bei unterschiedlichen Farbbadtemperaturen nachgestellt. Die sich innerhalb des ‘Färbebades’ ergebenden Partikelgrößenverteilungen werden mit Hilfe der Photonen-Korrelations-Spektroskopie analysiert.
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  • 48
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    Angewandte Makromolekulare Chemie 178 (1990), S. 33-46 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Durch Kondensation von p-Fluorphenol mit Formaldehyd wurde ein p-Fluorphenol-Formaldehyd-Novolak (NFF) hergestellt. Die Differential-Scanning-Calorimetrie zeigte je nach Vorgeschichte der Proben den normalen Glasübergang oder damit zusammenfallende endotherme Peaks. Es wird vermutet, daß die endothermen Peaks durch Spaltung intramolekularer Bindungen während des Glasübergangs verursacht werden. Diese Bindungen entstehen bei der Lagerung der Harze bei Raumtemperatur. Messungen des thermisch induzierten Polarisationsstroms (TSDC) wurden in einem Temperaturbereich von 290 bis 350 K an Proben mit Molekulargewichten von M̄n=375 bzw. 434 g/mol durchgeführt. Die TSDC-Kurven zeigten hauptsächlich die α-Peaks der dielektrischen Relaxation. Es wurde der Einfluß der Temperatur, der Einfluß von M̄n die Aktivierungsenergie Ea und die physikalische Alterung der Proben untersucht. Die physikalische Alterung wurde durch die reziproke Polarisierbarkeit R, als Funktion des Alters charakterisiert. Die Probe mit großerem M̄n wies eine höhere Glasübergangstemperatur, eine niedrigere Aktivierungsenergie und einen stärkeren Anstieg von Rp, auf als die Probe mit niedrigerem M̄n. Der Anstieg des Molekulargewichts verstärkte sich mit zunehmender Steifigkeit der NFF-Proben. Diese Effekte werden der starken Ausbildung von Wasserstoffbindungen zugeschrieben. Die Resultate werden mit analogen Ergebnissen von fluorfreien Phenol-Formaldehyd-Novolaken verglichen.
    Notes: A Novolac p-fluorophenol-formaldehyde (NFF) resin was prepared by condensation of p-fluorophenol with formaldehyde. DSC showed the glass transition effect or coinciding endothermal peak depending upon the thermal history of samples. It is supposed that the peaks are caused by breaking of the intermolecular bondings in the resin during the glass transition. The bondings are formed in the resin during the storage at room temperature. Thermally stimulated depolarization current (TSDC) measurements were carried out in the temperature range of 290 to 350 K, with the samples having an average number molecular weight M̄n of 375 and 434. TSDC curves mainly showed the dipolar relaxation α peaks. The influence of poling temperatures, the influence of M̄n, the activation energy Ea, and the physical ageing of the samples were investigated. Physical ageing was determined as the reciprocal polarizability Rp vs. time of ageing. Samples. with higher M̄n showed a higher glass transition temperature, a lower Ea, and a higher increase in Rp than the sample with lower M̄n. The increase in M̄n increased the rigidness of NFF samples. The effects are attributed to the strong hydrogen bonding. The comparison with analogous results in novolac phenol-formaldehyde resin without fluorine is given.
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  • 49
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    Angewandte Makromolekulare Chemie 178 (1990), S. 85-93 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurde die Synthese von Blockcopolymeren aus 6-Caprolactam und einem flüssigen aminotelechelischen Copolymeren aus 1,3-Butadien und Acrylnitril (Hycar ATBN 1300X21) studiert, die eine höhere Kerbschlagzähigkeit als das geläufige Poly(6-caprolactam) aufweisen. Bei der durch das Addukt aus Phosphorsäure und 6-Caprolactam initiierten Polymerisation von 6-Caprolactam wurde der Einfluß der Konzentration des Initiators (0-5 mol-%) und der Konzentration von Hycar ATBN 1300X21 (0-50 Gew.-%) im Polymerisationsgemisch, der Zeit (4-72 h) und der Temperatur (200-280°C) auf den Umsatz von 6-Caprolactam sowie auf die Eigenschaften des entstandenen Copolymeren untersucht. Die unter optimierten Bedingungen dargestellten Blockcopolymeren wiesen eine Kerbschlagzähigkeit von 13,5 kJ·m-2 auf.
    Notes: The preparation of block copolymers from 6-caprolactam and a liquid amine terminated butadiene-acrylonitrile copolymer Hycar ATBN 1300X21 having higher notched impact strength than ordinary poly(6-caprolactam) was studied. In the polymerization of 6-caprolactam initiated by an adduct of phosphoric acid with 6-caprolactam the influence of initiator concentration (0- 50 mol-%) and Hycar ATBN 1300X21 concentration (0-5 wt.-%) in the polymerization charge, of polymerization time (4 - 72 h) and of temperature (200-280°C) on the 6-caprolactam conversion and on the properties of the copolymers formed were followed. Notched impact strength of the block copolymers prepared under optimized conditions was as high as 13.5 kJ·m-2.
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  • 50
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    Angewandte Makromolekulare Chemie 178 (1990), S. 109-118 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß der Reaktionsdauer auf die mit Cer(IV)-Ionen initiierte Pfropfung von 4-Vinylpyridin (4-VP) auf partiell carboxymethylierte Cellulose (PCMC) mit verschiedenen Substitutionsgraden (D.S.) wurde untersucht. Zum Vergleich wurde dasselbe Monomere auf Baumwolle und mercerisierte Baumwolle gepfropft. Die Pfropfparamater dieser Polymerisationsreaktionen wurden bestimmt. Der Pfropfungsgrad (G) war bei PCMC signifikant höher als bei Baumwolle und mercerisierter Baumwolle. Der durch Röntgenbeugung ermittelte Kristallisationsgrad der Pfropfcopolymeren war niedriger als der von unmodifizierter Baumwolle. Der Einfluß der Reaktionszeit auf die Pfropfung von Baumwolle mit 2-Vinylpyridin wurde ebenfalls untersucht.
    Notes: A study was made of the time affecting the ceric ion induced grafting of 4-vinylpyridine (4-VP) onto partially carboxymethylated cotton (PCMC) having different degrees of substitution (D.S.). For comparison the same monomer was grafted onto cotton and mercerized cotton. The grafting parameters of these copolymerization reactions were determined. The graft yields for PCMC were significantly higher than those for unmodified cotton and mercerized cotton. The degree of crystallinity of the graft copolymers and of the unmodified cotton and PCMC samples was determined by the X-ray method. The crystallinity index decreased with the presence of grafted polymer. The reaction time effect of the grafting of 2-VP on cotton was also studied.
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  • 51
    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 photoinduzierte Polymerisation von Acrylaten in verschiedenen Bindemitteln wurde mit Hilfe der Photokalorimetrie, der DSC und der ESR-Spektroskopie untersucht. Um die Reaktivität vergleichend zu diskutieren, wurden zur Auswertung photokalorimetrischer Meßergebnisse folgende Parameter ausgewählt: Grenzumsatz, maximale Polymerisationsgeschwindigkeit, Inhibierungszeit und die Zeit, welche notwendig ist, um das Maximum der Polymerisationsgeschwindigkeit zu erreichen. Zwischen dem Grenzumsatz und der chemischen Struktur der Acrylate sowie dem Glaspunkt und der Sauerstoffpermeabilität des verwendeten Bindemittels bestehen eindeutige Korrelationen. Für die anderen Größen existieren keine deutlichen Zusammenhänge, da andere Faktoren wie z. B. ein verändertes Phasenverhalten order veränderte Diffusionsbedingungen diese Werte in komplexer Weise beeinflussen können.
    Notes: Photocalorimetry, differential scanning calorimetry and ESR-spectroscopy were used to analyse the photoinduced polymerization of multifunctional acrylic esters in various polymeric binders. Limiting conversion, maximal polymerization rate, inhibition time, and the time necessary to reach the maximum of the polymerization reaction rate were used to compare the reactivity of the photopolymer systems investigated in this work. Significant correlations exist between the limiting conversion and chemical structure of the acrylic esters used. A relation was also found between the glass transition temperature and oxygen permeability of the binder and the limiting conversion measured calorimetrically. A good correlation does not exist for the other reactivity parameters, because other factors such as phase change and changing diffusion conditions can have a complex influence on those values.
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  • 52
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    Angewandte Makromolekulare Chemie 178 (1990), S. 153-169 
    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 Arbeit befaßt sich mit dem Einfluß einer schwachen Phasenkopplung auf die viskoelastischen Eigenschaften von heterogenen Polymermischungen im linearen und nichtlinearen Deformationsbereich. Als Modellmischungen wurden Polyethylen Polyoxymethylen-Mischungen ausgewählt. Die beiden Polymeren eignen sich als Komponenten einer Modellmischung besonders gut, da sie vollständig unverträglich miteinander sind, da die Grenzflächenenergie groß und die Ausdehnung der Grenzschicht folglich gering ist und da die mechanischen Eigenschaften der beiden Komponenten in erster Näherung ahnlich sind. Solche Mischungen sollten folglich den Beitrag der Phasenkopplung zu den viskoelastischen Eigenschaften besonders deutlich aufzeigen.Für die Modellmischung wurden die viskoelastischen Eigenschaften als Funktion der Konzentration der Komponenten durch die Erfassung des Spannungs-Dehnungsver-haltens, des komplexen Schubmodulus sowie der elastischen, anelastischen und plastischen Anteile der Deformationsenergie charakterisiert. Der experimentelle Befund ist, daß sich die meisten der genannten Eigenschaften linear mit der Mischungszusammensetzung ändern und daß folglich die schwache Phasenkopplung keinen Einfluß auf die Eigenschaften der Mischungen hat. Eine Ausnahme ist die Bruchdehnung, die bei etwa gleichen Anteilen der beiden Komponenten in der Mischung einen Minimalwert aufweist. Insgesamt gilt, daß die Gegenwart von mechanisch schwachen Phasengrenzen einen iiberraschend geringen Einfluß auf die viskoelastischen Eigenschaften der Mischungen hat.
    Notes: The investigations reported in this paper aimed at evaluating the impact of a weak interfacial strength on visco-elastic properties in multiphase polymer blends both in the linear and nonlinear deformation regime. Blends of poly(ethylene) and poly(oxymethylene) were used as model systems. The particular choice of the components of the blend was based on the fact that the two components are incompatible, possess strong interfacial energies and thus narrow and weak interfacial layers, and finally that their individual visco-elastic properties are within the same order of magnitude. This allows to evaluate the contributions of the phase boundaries to the visco-elastic properties in a transparent way.We investigated the visco-elastic properties of blends of various compositions by analyzing the stress-strain behavior, the dynamical torsional behavior as well as by determinating their cyclic stress-strain behavior. The experimental finding is that most of the properties studied vary linearly with the composition and are not influenced by the weakness of the interfacial strength-contrary to the expectation. An exception is the elongation at break which varies nonlinearly with the composition and which shows a minimum value at intermediate compositions. The impact of a weak phase coupling on visco-elastic properties is thus rather limited.
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  • 53
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    Angewandte Makromolekulare Chemie 178 (1990), S. 191-200 
    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: Methyl-, Ethyl-, n-Propyl-, n-, i- und t-Butyl-, n-Hexyl-, 2-Ethylhexyl- und Laurylacrylat wurden in Benzol polymerisiert. Verdünnte Lösungen in THF einzelner Fraktionen dieser Polymeren wurden durch Lichtstreuungs- und Viskositätsmessungen untersucht. Polyacrylsäure wurde in Dioxan gemessen.Für die verschiedenen Polyacrylester und Polyacrylsäure wird die Molekulargewichtsabhängigkeit des Staudinger-Index [η] und des Trägheitsradius 〈r2w〉 angegeben.
    Notes: Dilute THF-solutions of different fractions of polymers of methyl, ethyl, n-propyl, n-, i- and t-butyl, n-hexyl, 2-ethylhexyl, and lauryl acrylate, prepared by solution polymerization in benzene, were studied by light scattering and viscosity methods. Poly(acrylic acid) was examined in dioxane. For the different polyacrylic esters the [η]-Mw-relations were established and the dependence of the radius of gyration 〈r2w〉 on the molecular weight was determined.
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  • 54
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    Angewandte Makromolekulare Chemie 178 (1990), S. 220-220 
    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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  • 55
    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: Anhand der erweiterten Kelen-Tüdős-Methode wurden Copolymerisationsparameter für Copolymerisationen mit Methylmethacrylat bzw. Styrol geprüft. Es wurden r-Werte einschließlich des 95% Vertrauensintervalls berechnet. Zur Klassifizierung des jeweiligen Systems wurden die Größen δ und Q angewendet. Bei der Copolymerisation mit Methylmethacrylat wurden 71 Systeme ausgewertet. Hiervon wurden 40 (56,3%) System der Klasse I und 20 (28,2%) Systeme der Klasse I(!) zugeordnet. Insgesamt ist also für 60 (84,5%) Monomerpaare die konventionelle Copolymerisationsglei- chung zutreffend. Für 3 (4,2%) Systeme, die der Klasse II zugeordnet werden, ist das Zwei-Parameter-Model1 ungültig. Zur Klasse 111 gehören 8 (I 1, Woo) Monomersysteme, für die die experimentellen Daten inkonsistent und die publizierten r-Werte unzutreffend sind. Im Falle der Copolymerisation mit Styrol wurden 32 Systeme ausgewertet, und es ergab sich folgende Einteilung in Klassen: 19 (59,4%) Systeme in Klasse I, 5 (15,6%) Systeme in Klasse I(!), 2 Systeme in Klasse I1 und 6 (18,8%) Systeme in Klasse 111.
    Notes: The reactivity ratios of selected methylmethacrylate or styrene copolymerisation systems have been reviewed in terms of the extended Kelen-Tüdős method. r-values, together with their 95% confidence limits have been calculated. Quantities δ and Q, suitable for classification of the systems, have been applied. Of the 71 reevaluated methylmethacrylate systems 40 (56.3%) were found to belong to class I and 20 (28.2%) to class I(!), i. e. 60 (84.5%) systems for which the conventional copolymerisation equation was found to be adequate. For 3 (4.2%) systems belonging to class II the two-parameter model does not hold and 8 (11.3%) systems were related to class III, i. e. systems for which the experimental data are inconsistent and the published r-values meaningless. 32 styrene copolymerisation systems were reevaluated with the following classification: 19 (59.4%) systems in class I, 5 (15.6%) systems in class I(!), 2 systems in class II and 6 (18.8%) in class III.
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  • 56
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: When exposed to the weather (moderate climate, Darmstadt), polymethylmethacrylate (PMMA) experiences weight changes, depending on the seasonal humidity, but no material loss. Polycarbonate (PC) on the other hand, and to a lesser degree PC with a “weather skin”, shows marked weight changes when exposed to artificial weathering (Xenotest 1200), which set in with some delay.Surface profile measurements across the borderline between exposed and covered material provide no evidence of material wear in the case of PMMA. With PC, and to a lesser degree with PC protected by a “weather skin”, wear does occur in the region of several μm. The extent of this material wear, which normally sets in with considerable delay after first exposure, is in good agreement with our weight loss measurements. The correlation between outdoor weathering and Xenotest weathering period (shortest wavelength 300 nm) is linear for all degrees of wear (time acceleration factor 13).Contrary to PMMA, scanning electron micrographs of PC show degradation morphologies dependent on the type of weathering which first develop after a certain weathering period.The degradation of PC occurs in two steps. Immediately after first weathering an embrittlement of the surface sets in, caused by molecular weight reduction and the formation of short-chain degradation products. Moreover, as a result of weathering-related dry/wet cycles and temperature fluctuations, the reduced elongation at break is exceeded locally and eventually cracking at the surface occurs, surface roughness and material loss increase and the gloss reduces.
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  • 57
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Low-density polyethylene was recycled in blown-film production using own factory scrap material. The amounts of the addition of recycled materials to the virgin polyethylene were established, having in mind the fullfilmet of the requirements for quality performances of the obtained films.In the second part of the paper several successive injection-mouldings were made on the same low-density polyethylene. Along with the mechanical characteristics of the obtained reprocessed polyethylene samples, the newly developed method for measuring thermally stimulated depolarization current (TSDC) was evaluated. It was found that the polyethylene samples reprocessed several times differ between themselves also by the fact that the current peaks appeared at some characteristic polymer temperatures, depending on the number of reprocessing cycles, and in lesser degree also, depending on the abcence or the presence of a heat stabilizer.
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  • 58
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This lecture summarizes some recent results and ideas about interrelations between degradation and mechanical behaviour of polyolefins. Aspects of the heterogeneous nature of oxidative degradation in the solid state, the feedback mechanism in degradation, effects of morphology, particularly orientation, on the degradation process, and the influence of degradation on plasticity and on the ultimate mechanical behaviour are discussed.
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  • 59
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In our work the degradative changes in properties of polyurethane adhesives based on aliphatic isocyanates were defined and compared with similar changes occurring when using aromatic isocyanates. The readily observed PUR adhesive discolouration in situations of its contact with leather does imply the necessity for the establishing the real proportions of the polyurethane constituents responsible for this ever-present problem. The structure-property relationship of hydroxylterminated polyester-based segmented aliphatic polyurethanes, as a component in adhesive composition were studied using wide angle X-ray diffraction spectroscopy (WAXD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) as well as attenuated total reflectance infrared spectroscopy (ATR-IR) and nuclear magnetic resonance spectroscopy (NMR). The results show that crystalline phase in segmented PUR component influence on morphological and structural properties in degradative conditions.
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  • 60
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of crushed rubber powder as a filler of rubber compounds on the ozone aging of vulcanizates has been investigated. It has been shown that the ozone resistance depends significantly both on the concentration and the degradation degree of the dispersed phase. Results of laboratory and atmospheric aging tests are summarized.
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  • 61
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Leather has been an important natural polymer undergoing aging when exposed to physical (temperature, radiation) and chemical (oxygen, water, metal ions) deteriogens. Degradation of collagen and changes of mechanical properties of leather are the consequences. The aging has been influenced by tan process, by changes of pH due to chemical degradation and by losses of fat due to extraction or blooming. The understanding of degradation process taking place in leather is necessary for the restoration of aged products from leather having a historical value.
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  • 62
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Electron-donating substituents of N-(arylamine) phthalimides and succinimides promote antioxidative efficiency of these compounds in thermooxidation of polypropylene (190°C, oxygen), while electron-withdrawing substituents contribute to a reduced volatilization of the polymer. 2,6-Ditert.butyl-4-methylphenol (ionol) raises the antioxidative efficiency of 4-methoxy and 4-methyl substituted derivatives displaying a distinct synergism.
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  • 63
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    Angewandte Makromolekulare Chemie 178 (1990), S. 1-16 
    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 seit langem in der Literatur als “Indophenin-Reaktion” bekannte Umsetzung von Isatin mit Thiophen wurde systematisch untersucht und auf die Umsetzung mit Bithiophen erweitert. Die Reaktionsprodukte wurden isoliert und durch FT-IR, UV, 1H-NMR, 13C-NMR sowie GPC charakterisiert.Im Gegensatz zu den Literaturdaten wurden Reaktionsprodukte mit höheren Molgewichten und anderer Molmassenverteilung gefunden. Die Reaktionsbedingungen - Lösungsmittel, Temperatur und Konzentration - sind für den Reaktionsablauf und die entstehenden Produkte von entscheidender Bedeutung.Füur die oligomeren Reaktionsprodukte werden neue Strukturen vorgeschlagen, die in Übereinstimmung mit allen analytischen Daten sind. Anhand eines Formelschemas werden die Reaktionen des Isatins mit Thiophen (Bithiophen) erläutert.
    Notes: A systematic study of the well-known indophenin reaction between isatin and thiophene was extended to embrace bithiophene. The products of the reactions were isolated and characterized by FT-IR, UV, 1H-NMR, 13C-NMR, and GPC. The values of the thus determined molar masses and molar mass distributions differed from the data given in the literature. The reaction conditions - solvent, temperature, and concentration - are of crucial importance for the course of the reaction and the products obtained.New structures suggested for the oligomeric reaction products agree with all the analytical data. The reactions between isatin and thiophene (bithiophene) are explained schematically.
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  • 64
    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: N,N'-Dibenzyl-3,6-dioxaoctane-diamine-1,8 and three analogous secondary diamines (EDA) all of which have long chain aliphatic ether groups were prepared and reacted with diglycidylether of bisphenol-A (DGEBA) to give well defined linear epoxide-amine addition polymers. Due to the flexible spacer in the amine component, the glass transition temperatures (Tg) of DGEBA/EDA copolymers decrease to 9-23°C. Likewise Tg's of DGEBA/polyamine networks are significantly lowered by copolymerization with EDA (Tg = 25 -100°C). Such flexible copolymers may be used as strain free optical adhesives or as the soft component in polymer blends and interpenetrating networks.Thermodynamic and kinetic polyreaction parameters were measured by DSC. In excellent correspondence with experiments, data have been calculated using a refined reaction model. This includes both noncatalyzed and catalyzed parallel reactions. The latter ones are activated by NH···HO complexation resulting from growing amounts of HO groups in the addition product.
    Notes: N,N'-Dibenzyl-3,6-dioxaoctandiamin-1,8 und drei analoge sekundäre Diamine mit langen aliphatischen Ethergruppierungen (EDA) sind hergestellt und mit Bisphenol-A-diglycidylether DGEBA polymerisiert worden. Der lineare Charakter der Additions-polymerisation wurde durch die Molmassenverteilung, Mw/Mn = 2, sowie elementaranalytische und spektroskopische Untersuchungen der Additionspolymeren und ihrer Hydroxylderivate (Acetate, Dicarbonsäurehalbester, Urethane) belegt.Durch ein verbessertes Reaktionsmodell wurde die Epoxid-Amin-Reaktion in ausgezeichneter Übereinstimmung mit dem Experiment (Zeit-Umsatz-Kurve und dynamische Wärmekapazitätsmessung) bis zum höchsmöglichen Umsatz beschrieben. Das Reaktionsmodell berücksichtigt die nichtkatalysierte Reaktion und eine durch Addukt-OH-Gruppen katalysierte Parallelreaktion.
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  • 65
    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: Les propriétés mécaniques dynamiques d'un assemblage collé type «sandwich» - acier inoxydable/adhésif en film - sont étudiées en fonction de I'épaisseur du film d'adhésif et du temps de vieillissement en atmosphere chaude et humide.A partir d'analyses thermomécaniques dynamiques, il est montré que les températures de transition vitreuse (Tg) de l'adhésif seul et de ce même adhésif dans un assemblage métal/adhésif sont différentes.Avant collage, la surface du métal subit divers traitements chimiques ou électrochimiques qui provoquent un déplacement de la température de transition vitreuse du polymère. L'évolution de cette même température avec l'épaisseur de l'adhésif montre que le taux de réticulation est plus élevé dans les couches superficielles de l'adhésif en contact avec le métal qu'au sein du polymkre.Lors du vieillissement, l'absorption d'eau entraîne des phénomknès de plastification de l'adhésif et une baisse importante de la température de transition vitreuse est observée. L'anodisation sulfochromique du métal confère une meilleure stabilitté à l'lassemblage.
    Notes: Dynamic mechanical properties of bounded joints - stainless steel/epoxy adhesive - are investigated as a function of the thickness of the adhesive and aging conditions. The viscoelastic properties of the bounded joints have been investigated by Dynamic Thermo Mechanical Analysis (DTMA).The glass transition temperature (Tg) showed a dependence on both the chemical/electrochemical pretreatments of the substrate and the thickness of the adhesive in the bounded joint. The crosslinking density in the adhesive thus seemed more important in the interfacial region than in adhesion bulk.The water uptake induces a plasticization of the adhesive and a decrease in Tg. The most stable bounded joints were obtained by carrying out sulfochromic acid anodization as a pretreatment step. The most important stability of the bounded joints was obtained with the sulfochromic anodization of the substrate.
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  • 66
    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: Sodium carboxy cellulose with a degree of substitution up to 0.8 can be prepared by oxidation of cellulose with NaNO2/H3PO4 and subsequent treatment with NaBH4. The extent of oxidation increases with raising molecular weight ranging from 170 to 1500 of the starting material. IR and NMR studies show that only the C-6 atom of the anhydroglucose unit is oxidized. The sodium carboxy celluloses show a high tendency to form ionotropic gels even in spherical shape with calcium ions. The mechanically stable gels are characterized by investigation of the swelling behaviour and SEM.
    Notes: Natriumcarboxycellulose mit einem Substitutionsgrad bis 0,8 kann durch Oxidation von Cellulose mit einem Polymerisationsgrad im Bereich von 170 bis 1500 mit NaNO2/H3PO4 und anschließender Behandlung mit NaBH4 hergestellt werden. Das Ausmaß der Oxidation steigt mit wachsender Molmasse des Ausgangsmaterials. IR-und NMR-Untersuchungen zeigen, daß nur das C-6-Atom der Anhydroglucoseeinheit oxidiert ist. Die Natriumcarboxycellulosen weisen eine hohe Tendenz zur ionotropen Gelbildung auch in sphärischer Form mit Calciumionen auf. Die mechanisch stabilen Gele werden durch Quellungsuntersuchungen und REM charakterisiert.
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  • 67
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    Angewandte Makromolekulare Chemie 178 (1990), S. 119-129 
    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 des pH-Wertes auf die mit Cer(IV)-ammoniumnitrat initiierte Pfropfpolymerisation von 4-Vinylpyridin (4-VP) auf Cellulose und partiell carboxymethylierte Cellulose (PCMC) in verdünnter Salpetersäure wurde untersucht. Die Abhängigkeiten von Pfropfausbeute (GE), Pfropfungsgrad (G), Pfropfhäufigkeit (GF) und Cerionenverbrauch (Ce(IV)c) von der Salpetersäurekonzentration wurden ermittelt. Bei pH = 1 sind Gesamtumsatz und Pfropfumsatz am größten; wird die Nitratkonzentration konstant gehalten (0,86 mol/1), läßt sich der Pfropfumsatz noch erhöhen. Zum Vergleich wurden einige Experimente mit Cersulfat als Initiator durchgeführt.
    Notes: The effect of pH on the graft polymerization of 4-vinylpyridine (4-VP) onto cellulose and on partially carboxymethylated cotton (PCMC) initiated by ceric ammonium nitrate (CAN) in dilute nitric acid was examined. The grafting parameters grafting efficiency (GE), graft yield (G), graft frequency (GF), and ceric ion consumption (Ce(IV)c) were studied as a function of nitric acid concentration. Also the effect of pH on the graft polymerization was examined and the total nitrate ion concentration was maintained high and constant at 0.86 mol/1 by addition of sodium nitrate. Maximum grafting and total conversion occurred at pH 1, but these values were smaller than the ones obtained in the previous case. For comparison some experiments were carried out using ceric sulfate as initiator.
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  • 68
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    Angewandte Makromolekulare Chemie 178 (1990), S. 143-151 
    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: It is shown in this paper, that during laser treatment of polymeric materials the occurrence of discolouring layers of laser crack deposits onto the substrate can be avoided without preventing the formation of a laser-induced microstructuring of the surface. Using water, alcohols, ethers or aqueous surfactant solutions as impregnating media during laser treatment a high degree of whiteness of fabrics can be maintained.
    Notes: Es wird gezeigt, daß die Ausbildung einer Schicht von verfärbenden Lasercrackprodukten - wie sie bei der Laserbehandlung von trockenen Polymeren gebildet wird - durch Imprägnierung mit verschiedenen Lösungsmitteln während der Laserbearbeitung verhindert werden kann. Die Ausbildung einer laserinduzierten Mikrostrukturierung der Polymeroberfläche wird davon nicht beeinflußt. Es läßt sich damit auch bei stärkeren Energiedichten der Laserbehandlung ein hoher Weißgrad aufrechterhalten.Zur Verhinderung der Vergilbung sind Wasser, Alkohole, Ether und wäßrige Tensidlösungen als Imprägniermedien während der Laserbestrahlung vorteilhaft einsetzbar.
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  • 69
    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 Bestrahlungsstabilität von statistischen und Blockcopolymeren aus Propen und Ethen (CP, Copolymeres mit 6% Etheneinheiten) mit und ohne Keimbildner (NA) wurde in bezug auf die Bestrahlungssterilisation von medizinischen Gütern verglichen. In beiden Fällen war die Bestrahlungsstabilität von CP in Gegenwart von NA geringer als ohne.Die Zugabe von NA zu CP verbesserte zwar nicht die Transparenz, die Kristallisation erfolgte aber bei höherer Temperatur. Sie hat deshalb den Vorteil kürzerer Formzeiten bei der Produktion von medizinischen Gütern.Die Bestrahlungsinstabilität von CP mit NA rührt von einer unterschiedlichen Kristallstruktur her, weil sich die Form der Spharolite von der des CP ohne NA unterscheidet. Weiterhin wurde durch Chemiluminiszenz-Analyse ein stärkerer oxidativer Abbau in der Probe mit NA beobachtet.
    Notes: The radiation stability of the random and block poly(propylene-co-ethylene) (CP, copolymer with 6% ethylene units) with and without nucleating agent (NA) was compared in relation to radiation sterilization of medical supplies. In both cases, it was found that the radiation stability of CP in the presence of NA was lower than that of CP without NA.Addition of NA to CP did not improve the transparency but the crystallization occurred at higher temperature. Thus, adding NA to CP has the advantage of shorter moulding time in the production of medical supplies.The radiation instability of the CP with NA was due to a different crystal structure, because the spherulite shape differs from that of CP without NA. Furthermore, by the chemiluminescence analysis, a higher oxidative degradation was observed in the sample with NA.
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  • 70
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    Angewandte Makromolekulare Chemie 174 (1990), S. 165-175 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Durch die Anwendung von hochaktiven Peroxiden kann die Polymerisationstemperatur bei der Synthese von Polyethylen niedriger Dichte abgesenkt werden. Um die Eignung einer Reihe von Peroxiden als Tieftemperatur-Initiatoren zu prüfen, wruden Polymerisationsversuche bei 1900 bar, 70 bis 140°C und einer mittleren Verweilzeit von 30 s in einer kontinuierlich betriebenen, mit einem Rührautoklaven ausgestatteten Laboranlage durchgeführt. Außer einer Reihe von Perneodecanoaten wurden zwei Peroxydicarbonate, ein Sulfonylperoxid und ein bifunktionelles Peroxid eingesetzt.Bei Polymerisationstemperaturen unter 100°C war der Initiatorverbrauch hoch. Es zeigten sich große Unterschiede zwischen den einzelnen Peroxiden. Mit steigender Temperatur nahm der Initiatorverbrauch rasch ab und war über 120°C bei den einzelnen Peroxiden nahezu gleich. Als gut geeignet für die angestrebten niedrigen Polymerisationstemperaturen erwies sich die bifunktionelle Verbindung 1,4-Di-(2-neodecanoyl-peroxy-isopropy1)-benzol, die bei 100°C einen Verbrauch von 13 g Initiatorkg PE zeigte. Bei einem Einsatz von 40 g Intiatorkg PE konnte eine Reaktortemperatur von 82°C eingestellt werden. Weniger gut schnitten die Peroxydicarbonate und das tert.-Butylperneodecanoat ab.
    Notes: By using highly active peroxides, it is possible to reduce the polymerization temperature necessary for the synthesis of low density polyethylene. In order to examine a number of peroxides for their suitability as low temperature initiators, polymerization tests were carried out at 1900 bar, 70-140°C, with an average residence time of 30 s in a continuously operating laboratory facility equipped with a stirred autoclave. Apart from a number of perneodecanoates, two peroxy dicarbonates, a sulphonyl peroxide, and a difunctional peroxide were used.The initiator consumption was high at polymerization temperatures below 100°C. The results obtained with the different peroxides varied considerably. As the temperature increased, the initiator consumption decreased rapidly to reach almost the same level for all the individual peroxides at above 120°C. The difunctional compound that proved highly suitable for the low polymerization temperatures desired was 1,4-di-(2-neodecanoyl peroxy isopropyl)benzene, the consumption at 100°C of which amounted to 13 g initiator/kg PE. Using a quantity of 40 g initiator/kg PE, a reactor temperature of 82°C could be employed. The peroxy dicarbonates and tertiary butyl perneodecanoate gave less satisfactory results.
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  • 71
    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 Modifizierung von Polybutylenterephthalat mit Gummi wurde durch Zugabe geeignet funktionalisierter Copolymerer aus Ethylen und Propylen (EPR) und gleichzeitiger Hochtemperaturpolykondensation von 1,4-Butandiol mit Dimethylterephthalat erreicht. Die Schlagzähigkeit der Blends, die reines oder mit Ester- oder Hydroxylgruppen modifiziertes EPR enthielten, wurde mit Hilfe von Schlagbiegeversuchen nach Charpy bei verschiedenen Temperaturen bestimmt. Die morphologischen Merkmale der Bruchflächen wurden auch untersucht. Es wurde ein Versuch unternommen, die Morphologie dieser Flächen mit den Bruchanalysenergebnissen zu korrelieren.
    Notes: Rubber modification of polybutyleneterephthalate was accomplished by the addition of suitable functionalized ethylene-propylene copolymers (EPR) concurrently with the high temperature polycondensation of 1,4-butanediol and dimethylterephthalate.The impact properties of blends obtained with plain EPR, with ester or hydroxyl groups modified EPR were analyzed by Charpy tests performed at different temperatures with a Ceast fracture pendulum. The morphological features of fracture surfaces have also been investigated. An attempt has been made to correlate the morphology of the surfaces with the fracture analysis results.
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  • 72
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    Angewandte Makromolekulare Chemie 174 (1990), S. 189-203 
    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 Sicherung von Produktqualität und Qualitätskonstanz bei der Polymerherstellung ist eine genaue Kenntnis des Polymerisationsprozesses notwendig. Für die Suspensionspolymerisation von Ethylen mit hochaktiven Ziegler-Katalysator/Cokatalysator-Systemen wurde ein Prozeß-Modell entwickelt. Dieses Modell gibt an, welcher Satz von Prozeßparametern innerhalb bestimmter Grenzen konstant gehalten werden muß, um die Produktdaten in den vorgegebenen Abnahmegrenzen zu halten. Die Konsequenzen für eine Produktionsanlage werden diskutiert.
    Notes: Saving product quality and quality consistency in polymer production needs a detailed knowledge of the polymerization process. A process model for the slurry polymerization of ethylene with high mileage Ziegler-catalyst/cocatalyst systems has been developed. This model teaches which set of process parameters must be kept constant together with their acceptable deviations to keep product data within the required frame. The consequences for a technical production plant are also discussed.
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  • 73
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    Angewandte Makromolekulare Chemie 174 (1990), S. 205-212 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The influence of the filler particle size and dispersion degree on the Charpy notch toughness (U notch) and tensile impact strength (without notch) in the polypropylene-microground calcium carbonate system was investigated. It was found that while the tensile impact strength was controlled by the content of particles and/or agglomerates coarser than about 10 µm (the strength decreased sharply with their increasing content), the Charpy notch toughness was not decreased even by large agglomerates (up to 100 µm), but dropped heavily with the increasing upper particle size of the filler measured before kneading into polymer. A model system polyethylene-glass beads revealed even an increase of the notch toughness with the increasing upper diameter of the glass beads (the upper diameter being in the 50-400 µm range).
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  • 74
    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: Tragersubstanzen auf Acrylbasis wurden durch Aminolyse von Nitril- oder Estergruppen in Co. oder Terpolymeren aus Acrylnitril oder Acrylsäureestern und Divinylbenzol oder Ethylendimethacrylat in Gegenwart inerter Solventien hergestellt. Der Einfluß der übermolekularen Struktur dieser Trägersubstanzen, die durch Zugabe inerter Solventien während der Suspensionspolymerisation erzeugt wurde, auf deren Tragereigenschaften wurde untersucht. Geeignete Trägersubstanzen zur Immobilisierung von Penicillinacylase wurden entweder aus porösen oder ‘Sol’-Typ-Copolymeren erhalten; sie zeigten nach der Aminolyse die Struktur eines expandierten Gels.
    Notes: Acrylic carriers were obtained by aminolysis of nitrile or ester groups in copolymers or terpolymers synthesized from acrylonitrile, acrylic esters and divinylbenzene or ethylene dimethacrylate in the presence of a mixture of inert diluents. The influence of the supermolecular structure of these carriers, generated during the suspension polymerization by adding a mixture of inert diluents, on the carrier properties was observed. Acrylic carriers for immobilization of penicillin acylase should be obtained from either porous or ‘sol’-type copolymers which aquire after aminolysis the structure of expanded gel.
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  • 75
    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: Irradiation of biaxially stretched poly(ethyleneterephthalate) (PETP)-films by UV-excimer wavelengths gives rise to well-known morphological surface modifications. Using a slit or a circular aperture a characteristic pattern due to Fresnel diffraction is imprinted onto this effect. The diffraction of the laser light leads to local variations of intensity on the PETP-surface. Using this diffraction effect a hitherto unknown fluence threshold for the appearance of laser induced surface morphology can be determined. This threshold is markedly lower than the threshold for ablation obtained by conventional extrapolation of laser etching data. Using elastomeric fibers furthermore it is shown that the energy limit for the onset surface structures is dependent on the amount of externally applied tension fields.
    Notes: Bei UV-Excimer-Laserbestrahlung von biaxial verstreckten Poly(ethylenterephthalat) (PETP)-Folien durch einen Spalt oder durch kreisförmige Blenden entstehen unter geeigneten Bestrahlungsbedingungen die bekannten charakteristischen Strukturierungen, welche durch Fresnelsche Beugungserscheinungen modifiziert sind. Die Beugung des Laserlichtes führt zu lokalen Intensitätsunterschieden auf der PETP-Oberfläche. Unter Ausnutzung dieses Beugungseffektes wurde eine higher nicht gemessene Grenzenergie für die laserinduzierte Ausbildung der Oberflächenmorphologie von PETP bestimmt. Wesentlich ist hierbei, daß diese Strukturschwellenenergie deutlich unterhalb der extrapolierten Ablationsschwellenenergie von PETP liegt. Darüber hinaus wird an Elastomerfasern aufgezeigt, daß die Grenzenergie zur Strukturbildung auch von der Größe eines extern aufgebrachten Spannungsfeldes abhängt.
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  • 76
    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: Polyvinylchlorid wurde mit verschiedenen Polymethacrylaten und Polycarbonaten durch Ausfällen gemeinsamer Lösungen gemischt. Die thermische Stabilität der Proben wurde bei 180°C in einer Stickstoffatmosphäre mittels konduktometrischer Messung der abgespaltenen Salzsäure bestimmt. Um den Einfluß der Polymethacrylate auf die Länge der entstandenen Polyensequenzen zu ermitteln, wurden die abgebauten Proben UV-spektroskopisch untersucht.Wie die Experimente zeigen, ist die Estergruppe von dominierendem Einfluß auf die thermische Stabilität von Polyvinylchlorid in diesen Blends. Poly-n-butylmethacrylat stabilisiert dabei Polyvinylchlorid am besten. Die eingesetzten Polycarbonate haben Glastemperaturen, die über der Abbautemperatur liegen; sie vermindern die thermische Stabilität von Polyvinylchlorid.Stabilisierungsversuche mit Dibutylzinn-bis(isooctylthioglykolat) zeigen einen costabilisierenden Effekt der Polymethacrylate und Polycarbonate.
    Notes: Poly(vinyl chloride) was mixed with various poly(methacrylate)s and polycarbonates by combined precipitation from common solutions. The thermal stability of the samples was measured at 180°C under nitrogen, the HCl evolved was detected by conductometry.UV-Vis-spectra of degraded samples were measured to investigate the influence of the poly(methacrylate)s on the lengths of polyenes formed during the degradation of poly(vinyl chloride).The experiments show that the nature of the ester group is the dominating factor for the thermal stability of poly(vinyl chloride) in these blends. Poly(n-butylmethacrylate) exhibits the best stabilization for poly(vinyl chloride) in this series. Polycarbonates with a higher glass transition temperature than the temperature of degradation destabilize poly(vinyl chloride).Stabilization experiments with dibutyltin-bis(isooctylthioglycolate) show a costabilizing effect of the poly(methacrylate)s and polycarbonates.
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  • 77
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    Angewandte Makromolekulare Chemie 181 (1990), S. 93-101 
    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: Mehrkomponentige Komplexe eines typischen Polyelektrolyten wie Polyacrylsäure (PAA) mit nichtionogenen Polymeren (PVP and PEO) und Übergangsmetallionen (Cu(ll) und NI(II)) wurden hergestellt und mittels Viskosimetrie, Potentiometrie, Leitfähigkeitsmessungen und IR-Spektroskopie untersucht. Ein Schema, welches die Bildung dieser Komplexe erklärt, wird vorgeschlagen.
    Notes: Multicompoent complexes of a typical polyelectrolyte like poly(acrylic acid) (PAA) have been prepared by incorporating transition metal ions (e. g. Cu(ll) and Ni(ll)) and non-ionic polymers (e. g. PVP, PEO) in the polyelectrolyte chain in a definite sequence. The formation of these complexes has been studied by several techniques, such as viscometry, potentiometry, conductometry, and IR spectroscopy. A scheme is suggested to explain the mode of formation of such complexes.
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  • 78
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    Angewandte Makromolekulare Chemie 181 (1990), S. 75-84 
    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 Härtungsreaktion von Harzen aus Bisphenol A-diglycidylether (DGEBA) und zwei-oder dreiwertigen Alkoholen mit Phthalsäureanhydrid als Härter und Triethylamin als Katalysator mit und ohne Beschleuniger wurde mit Hilfe der Differential-Scanning-Calorimetrie (DSC) ebenso untersucht wie die thermische Stabilität der gehärteten Produkte durch thermogravimetrische Analyse (TGA). Unter Berücksichtigung dieser Untersuchungen wurden glasfaserverstärkte Epoxidverbundwerkstoffe hergestellt und auf ihre mechanischen, elektrischen und chemischen Eigenschaften untersucht.Es wurden Aktivierungsenergien der Härtungsreaktion zwischen 75,1 und 88,3 kJ mol-1 gemessen. Die gehärteten Produkte zeigten eine gute thermische Stabilität; die Verbundwerkstoffe besitzen eine hohe mechanische Festigkeit, gute elektrische Isolationseigenschaften und eine hohe Chemikalienresistenz. Durch Zugabe von Beschleunigern bei der Härtung konnte die Biegefestigkeit zusätzlich um 36 bis 53% verbessert werden.
    Notes: Differential scanning calorimetry (DSC) technique was used to study the curing reaction of diglycidyl ether of bisphenol A (DGEBA) resin and different di- and trifunctional polyhydric alcohols with phthalic anhydride as curing agent and triethylamine as catalyst with or without fortifier. The thermal stability of the cured products was also studied by thermogravimetric analysis (TGA). Using these data, different glass fiber reinforced epoxy composites were fabricated and their mechanical and electrical properties and their resistance to chemicals were studied as well. Activation energies of curing reactions range within 75.1 to 88.3 kJ mol-1. The cured products have good thermal stability; the composites have good mechanical strength, electrical insulation properties and chemical resistance. 36 to 53% improvement in flexural strength has been observed when fortifier was added to the DGEBA-diluent systems.
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  • 79
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    Angewandte Makromolekulare Chemie 181 (1990), S. 119-128 
    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 Strom-Spannungs-Charakteristika von Verbundwerkstoffen aus gepfropftem Polypropylen und Aluminium wurden mit Gleichstrom untersucht. Es wird ein Modell vorgeschlagen, das die elektrischen Eigenschaften der Polymer-Metall-Grenzfläche beschreibt. Es beinhaltet einen konstanten Schottky-Effekt und eine Raumladung, die von den Hafteigenschaften abhängt und den Carboxygruppen des gepfropften Polypropylens an der Aluminiumoberfläche zugeordnet werden kann.
    Notes: L'étude des caractéristiques intensité-potentiel en courant continu pour des assemblages films de polypropylènes greffés-aluminium permet de proposer un modèle électrique de I'interface polymère-métal, associant une barrière de Schottky constante à une charge d'espace modulée selon le niveau d'adhésion. Cette charge d'espace est liée à l'afflux des groupements carboxyliques greffés sur le polypropylène vers la surface de l'aluminium. La présence d'une interphase dans l'adhésion entre polyoléfine et métal est ainsi prise en compte dans les mesures électriques.
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  • 80
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    Angewandte Makromolekulare Chemie 181 (1990), S. 143-152 
    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: Im Temperaturbereich 80-98°C wurde die Oxidation von Caprolactam verfolgt, die durch 0,008 - 0,82 mol/kg 1,1′-Azo-bis(cyclohexancarbonitril) initiiert wurde. In den Produkten der bis zu einem Umsatz von max. 3% durchgeführten Oxidation wurden Caprolactamhydroperoxid, Adipinsäureimid und Wasserstoffperoxid nachgewiesen. Die von der Konzentration des Initiators abhängigen kinetischen Kettenlängen der Oxidation betrugen 3 - 30, wobei die Geschwindigkeit der Wasserstoffhydroperoxidbildung halb so groß wie die Initiierungsreaktionsgeschwindigkeit war. Bei der thermisch initiierten Oxidation mit einer kinetischen Kettenlänge um 300 entstand keine nachweisbare Wasserstoffperoxidkonzentration. Es kann also angenommen werden, daß bei der bimolekularen Abbruchreaktion der Caprolactamperoxyradikale Wasserstoffperoxid und Adipinsäureimid entstehen. Adipinsäureimid wird auch durch den monomolekularen Zerfall der Peroxyradikale gebildet, die neben der Oxidation von Caprolactamradikalen auch durch den Zerfall von Caprolactamhydroperoxid entstehen können.
    Notes: The oxidation of caprolactam initiated with 0.008-0.82 mol/kg 1,1′-azo-di(cyclohexane carbonitrile) was studied in the temperature range 80-98°C. At the conversion lower than 3%, caprolactam hydroperoxide, adipimide, and hydrogen peroxide were determined in the oxidation products. Depending on the initiator concentration, the kinetic chain length of oxidation ranged between 3 and 30. The formation rate of hydrogen peroxide was equal to one half of the rate of initiation reaction, i. e. to one half of the rate of bimolecular termination in the steady state. It may be assumed that hydrogen peroxide is formed by the bimolecular termination reaction. This is in agreement with the fact that hydrogen peroxide was not found in the thermally initiated oxidation of caprolactam which proceeded with the kinetic chain length more than 300. Another product of the bimolecular termination reaction of caprolactam peroxy radicals is adipimide, which is also formed by their monomolecular decomposition.
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  • 81
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    Angewandte Makromolekulare Chemie 181 (1990), S. 171-182 
    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 Reaktion von 2-Chlorethanol und Epichlorhydrin (ECH) mit Alkalisalzen von partiell hydrolysierten Methylmethacrylat-(MMA)-Polymeren sowie MMA-Copolymeren, die freie Carboxygruppen enthielten, wurde untersucht. Quaternäre Ammoniumhalogenide R4NX sind effektive Katalysatoren dieser Reaktionen. Bis zu 80% der Carboxylatgruppen wurden in Hydroxyethylestergruppen unter Bildung vollständig löslicher Copolymerer umgewandelt. Bei der Reaktion von ECH mit Alkalisalzen der Copolymeren wurden vernetzte Produkte erhalten. Bei Durchführung der Reaktion in Gegenwart von R4NX konnte der Gelanteil von 87% auf 5% vermindert werden.MMA-Copolymere mit freien Carboxygruppen reagieren mit überschüssigem ECH in Gegenwart von R4NX über die Chlorhydrinester-Stufe mit nachfolgender Dehydrochlorierung (Transepoxidierung) unter Bildung vollständig löslicher Glycidylester-Copolyrnerer mit niedrigem Chlorgehalt (≤ 0.4%) und Ausbeuten an Epoxidgruppen ≤ 95%.
    Notes: The reactions of 2-chloroethanol and epichlorohydrin (ECH), respectively, with alkali salts of partially hydrolyzed methyl methacrylate (MMA) polymers as well as with MMA copolymers containing free carboxy groups were studied. Quaternary ammonium halogenides R4NX are effective catalysts of these reactions. Up to 80% of alkali carboxylate groups were converted into hydroxyethyl ester groups to yield completely soluble copolymers. By reaction of ECH with alkali salts of the copolymers, crosslinked products were obtained. The gel fraction may be reduced from 87% to 5% if the reaction is carried out in the presence of R4NX. MMA-copolymers containing free carboxy groups react with an excess of ECH in the presence of R4NX via the chlorohydrin ester and dehydrochlorination (transepoxidation) to produce completely soluble glycidyl ester copolymers of low chlorine content (≤0.4%). Yields of epoxy groups up to 95% have been attained.
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  • 82
    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: Einige Abkdmmlinge der Poly(α, β-,L-asparaginslure) (2) rnit Aminogruppen in der Seitenkette wurden zur Verwendung als makromolekulare Wirkstofftrager hergestellt. Die Strukturen der Zielpolymeren wurden im Hinblick auf vollstandige Wasserlöslichkeit als Voraussetzung fur eine schonende intraven6se Anwendung gewtihlt; die Strategie dieser Seitenkettenmodifizierung bringt die gestellte Forderung zum Ausdruck, alle Reaktionsschritte in teilweise oder vollstandig waRriger Phase durchzufuhren. Die Poly(asparaginsaure) (2)  -  ein bekanntes Polyamid, hergestellt aus Poly(bernsteinsaureimid) (1) und sowohl mit α- als such P-Peptideinheiten in der Polymerkette  -  wurde rnit Ethylendiamin, Diethylentriamin, N-(2-Hydroxyethyl)-ethylendiamin und Hydrazin in Gegenwart wasserldslicher Carbodiimide umgesetzt. Dies fiihrte zu den modifizierten Poly(asparaginen) 3 bis 6 rnit primaren Aminogruppen in der Seitenkette. Wirksamer und unter Umgehung der Poly(asparaginsaure) (2) als Zwischenstufe erwies sich die direkte nucleophile Offnung des Imidringes in 1 mit den gleichen Aminen. Die wasserloslichen Poly(asparagine) 3 bis 6 wurden analytisch und spektroskopisch charakterisiert; sie zeigten inharente Viskositaten (qinh) zwischen 5 und 20 ml g-1 und besaRen die strukturellen Voraussetzungen zur Verankerung von Wirkstoffen an der Seitenkette bedingt durch die Modifizierung rnit Aminogruppen. Die Substituierbarkeit dieser funktionellen Gruppen als ein Ma6 fur die Fahigkeit zur Wirkstoffimmobilisierung wurde anhand der Umsetzung von 5 und 6 zu den N-acryloylierten Derivaten 7 und 8  -  und weiterer Umsetzung von 7 zu 9  -  und anhand der Kondensation von 5-Formylsalicylsaure mit der  -  zweizahnigen  -  Etylendiaminseitengruppe in 4 zur entsprechenden Verbindung 10 rnit einer bioaktiven Salicylgruppe als Seitenkettenkomponente gezeigt.
    Notes: Several derivatives of poly(α,β-D,L-aspartic acid) (2) comprising amine functions as side chain components are synthesized for use as macromolecular drug carriers. The structures of the target polymers are designed so as to provide complete solubility in water, a prerequisite for smooth intravenous administration, and the strategy of derivatization reflects the requirement for the performance of all reaction steps in a partially or entirely aqueous phase. The poly(aspartic acid) (2)  -  a known synthetic polyamide obtained from poly(succinimide) (1) and composed of both α- and β- peptide units in the chain  -  is coupled with ethylenediamine, diethylenetriamine, N-(2-hydroxyethyl)ethylenediamine, and hydrazine, respectively, in the presence of water-soluble carbodiimides. This gives the poly(aspartamides) 3 to 6 possessing primary amino side groups. More efficaciously, circumventing the intermediacy of the polyacid 2, polymers 3 to 6 are obtained through nucleophilic opening of the imide rings in 1 by the same amine reactants. The analytically and spectroscopically characterized, water-soluble target polymers 3 to 6 have inherent viscosities ranging from 5 to 20 ml g-1 and possess the structural prerequisites for side-chain drug anchoring involving the spacer-bound amino groups. The susceptibility of these functional groups to substitution as a measure of their drug binding capabilities is demonstrated by conversion of 5 and 6 to the N-acryloylated derivatives 7 and 8  -  with 7 further derivatized to give 9  -  and by condensation of 5-formylsalicylic acid with the bidentate  -  ethylenediamine side group in 4 to give the conjugate 10 containing the bioactive salicylyl group as a side-chain component.
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  • 83
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    Angewandte Makromolekulare Chemie 181 (1990), S. 199-205 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein neues o-Kresol-Novolak-Epoxidharz mit Oxyethylen-Einheiten wurde hergestellt und charakterisiert. Die thermischen und mechanischen Eigenschaften des mit Methylhexahydrophthalsäureanhydrid gehärteten Harzes wurden untersucht und mit einem konventionellen o-Kresol-Novolak-Epoxidharz (EOCN 1020) verglichen; das neue Epoxidharz zeigte dabei nach dem Härten eine höhere Flexibilität als das herkömmliche.
    Notes: A new o-cresol novolak epoxy resin containing oxyethylene units was synthesized and characterized. The mechanical, thermal, and dynamic mechanical properties of resins cured with methyl hexahydrophthalic anhydride were examined and compared to those of a conventional o-cresol novolak epoxy resin (EOCN 1020). This new epoxy resin gives a cured resin with higher flexibility, compared to the conventional one.
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  • 84
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    Angewandte Makromolekulare Chemie 182 (1990), S. 63-72 
    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: Papierzellstoff wurde aus Bananenstaudenholz hergestellt und mit Allylchlorid in Diisopropylether bei 60 °C modifiziert; dabei wurde ein durchschnittlicher Substitutionsgrad von 0,215 Allylchlorid-Bausteinen pro Anhydroglucose-Einheit (AGU) erreicht. Die Pfropfcopolymerisation von Methylmethacrylat auf modifizierten und nicht modifizierten Papierzellstoff wurde bei 29 °C mit Ammoniumcer(IV)-sulfat ((NH4)4 Ce(SO4)4) als Initiator durchgeführt. Aus der Abhängigkeit der Pfropfausbeute von der Cer(IV)-Konzentration wurde gefunden, daß der Abbruch der Pfropfpolymerisation im wesentlichen durch Reaktion mit Cer(IV)-Ionen erfolgt und daß die Pfropfausbeute durch die Modifizierung ausgesprochen erhöht wird. Der Einfluß von Isopropanol in verschiedener Konzentration auf die Pfropfausbeute von modifiziertem Material wurde ebenfalls untersucht.
    Notes: Plantain pulp was modified by treatment with allyl chloride in diisopropyl ether at 60 °C which results in an average degree of substitution of 0.215 allyl chloride moieties per anhydroglucose unit (AGU). Graft copolymerization of methyl methacrylate onto modified and unmodified pulp was carried out at 29 °C using various concentrations of ceric ion initiator. It was found from the dependence of the extent of graft polymer formation on ceric ion concentration that termination of graft polymerization occurred mainly by the interaction of growing graft polymer chains with ceric ion and that the extent of graft polymer formation was markedly enhanced by the modification of the plantain pulp. The effect of isopropanol on the extent of graft polymer formation on the modified material was also examined.
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  • 85
    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: Hydrophobic surfaces of poly(propylene) (PP)-films are modified to hydrophilic ones by UV-laser-induced grafting of acrylic acid. The dependence of graft yield on experimental conditions is investigated. In contrast to grafting with low intensity UV-radiation (high pressure mercury lamp) the UV-laser-induced grafting is very effective because of short radiation times needed and because no photoinitiators and photosensibilisators are required.
    Notes: Oberflächen von Polypropylen (PP)-Folien werden durch UV-laserinduzierte Pfropfcopolymerisationsreaktionen von Acrylsäure anionisch modifiziert. Die Bestrahlung der hydrophoben PP-Folien erzeugt hierbei eine Hydrophilie. Die Ausbeute von aufgepfropften Polyacrylsäure-Seitenketten wird in Abhängigkeit der experimentellen Parameter bestimmt. Im Gegensatz zu Pfropfcopolymerisationsreaktionen mit herkömmlichen UV-Strahlungsquellen (Hg-Hochdruckdampflampen) kann schon mit sehr kurzen UV-Laserbestrahlungszeiten eine chemische Modifizierung der PP-Oberfläche erzielt werden. Darüber hinaus ist die Verwendung von Photoinitiatoren und Photosensibilisatoren nicht notwendig.
    Additional Material: 4 Ill.
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  • 86
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 182 (1990), S. 205-205 
    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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  • 87
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 182 (1990), S. 193-203 
    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: Polyurethanpräpolymere (PU) auf der Basis von Poly(butylenadipaten) (PBA) bzw. Poly(oxytetramethylen) polyolen (PTMO) wurden als Vernetzer für Bisphenol-A-diglycidylether (DGEBA) eingesetzt. Anschließend wurde DGEBA mit einem tertiären Amin zu einem PU-vernetzten DGEBA ausgehärtet. Die Reißfestigkeit sowohl von PU(PBA)-als auch von PU(PTMO)-vernetzten Systemen stieg mit steigendem PU-Gehalt bis zu einem Maximum an, um bei noch höheren Gehalten von PU wieder abzufallen. Hinsichtlich der Izod-Schlagzähigkeit brachte die Vernetzung des DGEBA mit PU(PBA) eine wesentlich bedeutendere Verbesserung als mit PU(PTMO). Andererseits zeigten PU(PTMO)-vernetzte DGEBA-Polymere viel höhere Werte der Bruchenergie G1 C als PU(PBA)-vernetzte.
    Notes: Polyurethane (PU) prepolymers based on poly(butylene adipate) (PBA) and poly(oxytetramethylene) (PTMO) polyols were employed as a crosslinking agent to the diglycidyl ether of bisphenol A (DGEBA). Then the DGEBA was cured with a tertiary amine catalyst to form PU-crosslinked DGEBA.The tensile strength of both the PU(PBA)-crosslinked DGEBA and PU(PTMO)-crosslinked DGEBA systems increased to a maximum value with increasing PU content in the system and then decreased with further increasing PU content.Izod impact property of these PU-crosslinked DGEBA indicated that the PU(PBA)-crosslinked DGEBA had much more significant improvement than the PU(PTMO)-crosslinked DGEBA. On the contrary, the fracture energy (G1 C value) of the resultant PU-crosslinked DGEBA showed that the PU(PTMO)-crosslinked DGEBA had much higher G1 C values than the PU(PBA)-crosslinked DGEBA.
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  • 88
    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: Nach einem kurzen überblick über die verschiedenen lichtinduzierten radikalischen Polymerisationen werden die wichtigsten Anwendungen solcher Reaktionen beschrieben. Ausführlich wird über die Verwendung von Azaaromaten als Photosensibilisatoren und die damit ausgelösten Startmechanismen berichtet.
    Notes: After a short survey on the various types of light-induced free radical polymerisations the most important applications of such reactions are summarized. In some detail is reported on the use of aza-aromatic compounds as photo-sensitizers and their initiation mechanism is discussed.
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  • 89
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the first part a survey is given on UV screeners, UV absorbers, quenchers of excited states, antioxidants and peroxide decomposers.In the second part UV absorbers, e. g. Tinuvin P (2-(2'-hydroxy-5'-methylphenyl) benzotriazole, Scheme 8) are described in detail where intramolecular proton transfer occurs in the excited state (TIN(intra) ). This proton transfer may be accompanied and/or followed by very fast and effective temperature dependent radiationless deactivation processes which are promoted by internal vibrations and librations of the molecule. - In polar solvents or in polymers with polar groups some of the molecules convert their intramolecular hydrogen bond into an intermolecular one (TIN (inter) ). TIN (inter) cannot be considered any longer as UV stabilizer. Due to its high triplet quantum yield it may even initiate photodegradation processes of itself and of the polymer. From this follows that the TIN molecule can only act as stabilizer if the intramolecular hydrogen bond is intact. This can be answered from the UV absorption spectrum.
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  • 90
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We show how narrow spectral holes burnt into the inhomogeneous absorption of dye doped polymers can be used as extremely sensitive detectors for measuring structural rearrangement processes. A model is suggested which relates the observed hole burning phenomena to the specific heat of the conformation phase space.
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  • 91
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wird eine neue Klasse von orienterten Polymeren vorgestellt: hoch-vernetzte Polymere, geschaffen durch Photopolymerisation von orientierten flüssigkristallinen (LC) Monomeren. Die Orientierung dieser Polymere kann in ähnlicher Weise induziert werden wie bei konventionellen LC's, wie es in LCD's angewandt wird: mit Hilfe eines elektrischen oder magnetischen Feldes oder durch Oberflälchenorientierung.Die Photopolymerisation bietet den Vorteil, daß eine Temperatur genau im LC-Bereich gewählt werden kann.Die resultierenden Polymernetzwerke zeigen einen hohen Ordnungsgrad, welcher einigermaßen abhängig ist von der Polymerisationstemperatur, wie nachgewiesen durch Doppelbrechungsmessungen. Diese Ordnung wird über einem weiten Temperaturbereich aufrechterhalten, im Gegensatz zu der Ordnung in LC-Seitenkettenpolymeren. Abgesehen von ihren optischen Eigenschaften, zeigen unaxial geordnete Polymernetzwerke Anisotropie auch in anderen physikalischen Eigenschaften, wie im thermischen Ausdehnungskoeffizienten und im Elastizitätsmodul.
    Notes: In this paper a new class of oriented polymers is introduced: highly crosslinked polymer networks obtained by photopolymerization of oriented liquid crystalline (LC) monomers. Orientation of these monomers can be induced in the same manner as usual for conventional LCs applied in LCDs: with the aid of an electric or a magnetic field, or using surface orientation. Photopolymerization offers the advantage that a temperature can be chosen right within the LC temperature region.The resulting polymer networks show a high degree of ordering which is somewhat dependent on the polymerization temperature, as demonstrated by the amount of birefringence. This ordering is maintained over a wide temperature region, contrary to that in LC side-chain polymers. Apart from their optical properties, uniaxially ordered polymer networks show anisotropy also in other physical properties, such as the thermal expansion coefficient and modulus.
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  • 92
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Low molar mass and polymeric liquid crystals display extremely large electro-optical and nonlinear optical responses, due to a combination of orientational long range order and fluidity. These responses are controlled on the one hand by the intrinsic anisotropic dielectric and optical properties of these phases and on the other hand by their peculiar curvature elastic and viscous properties.Polymeric liquid crystals, although having the disadvantage of longer response times, offer the advantage that the liquid crystalline state and any modulation imposed on it can be frozen in a glassy state. Polymeric liquid crystals can thus be used in various applications related to the control of light propagation, optical information storage and the manufacturing of holographic optical elements.
    Additional Material: 19 Ill.
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  • 93
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Usually two phase polymer blends are not transparent because of differences in the refractive indices of their components and the resulting light scattering. By means of model calculations on the basis of the Mie-theory, the conditions for transparency in two-phase polymer blends are investigated. The models used are homogeneous spheres or spheres with a core-shell morphology imbedded in the polymer matrix. The light scattering of these particles is calculated as a function of diameter, refractive index, wavelength and particlecomposition. Results are presented that show the limits of diameter and difference in the refractive indices between matrix and particle for homogeneous particles to obtain transparency. In the case of large differences in the refractive indices or of large diameters the use of spheres with a core-shell morphology is favourable. Depending on the refractive indices of the respective phases, there exists an optimal composition of these spheres to obtain transparent polymer-blends. Another way to transparency is the minimization of light scattering by interparticle interferences, which can be achieved by special types of block-copolymers.
    Additional Material: 13 Ill.
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  • 94
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The synthesis and characterization of thermotropic main-chain liquid-crystalline polyethers MBPE-X and copolyethers MBPE-X/Y based on 3-methyl-4,4′-ethylenediphenol [1-(4-hydroxyphenyl)-2-(2-methyl-4-hydroxyphenyl)ethane (MBPE)], which is flexible rod-like mesogenic unit or a rod-like mesogenic unit based on conformational isomerism, and flexible spacers containing an even number of methylene units, X, Y, are described. The particular examples presented in this paper refer to polyethers MBPE-4, MBPE-6, MBPE-8, MBPE-10, and MBPE-12, and copolyethers MBPE-X/Y; where X,Y = 4, 6, 8, 10, 12. MBPE-4, MBPE-6, MBPE-10 and MBPE-12 are crystalline. MBPE-8 displays an enantiotropic nematic mesophase. Copolymerization of MBPE with different pairs of spacers containing even numbers of methylene units leads to MBPE-X/Y copolymers displaying monotropic or enantiotropic nematic mesophases. Both liquid-crystalline transition temperatures and the corresponding enthalpy changes of the copolymers represent weight-averaged values of the similar parameters of the parent homopolymers. Extrapolation of the isotropic-nematic and nematic-isotropic transition temperatures and their corresponding enthalpy changes demonstrated that all homopolymers containing an even number of methylene units in the flexible spacer exhibit virtual nematic mesophases. The virtual isotropic-nematic transition temperatures and the corresponding enthalpy changes were determined for MBPE-4, MBPE-6, MBPE-10 and MBPE-12. The virtual nematic-isotropic transition and the corresponding enthalpy changes could be determined only for MBPE-10 and MBPE-12.
    Additional Material: 8 Ill.
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  • 95
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 191 (1990), S. 71-79 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Some unexpected results were observed in the phase transfer of catalyzed (PTC) (two phase, aqueous-organic) polymerization of α,ω-dibromoalkanes with sodium sulfide. Alkane dielectrophiles containing fewer than six methylene units give rise to large, and sometimes quantitative, amounts of cyclic thioethers. These cyclic sulfides are formed under “polymerization” conditions and can be minimized by using only the monomer as the organic phase. Alkane dielectrophiles containing more than six methylene units yield only polymer. When a comonomer system composed of a 1:1 mixture of 1,4-dibromobutane (DBB) and 1,8-dibromooctane (DBO) is employed, the resulting copolymer's molecular weight and polydispersity are vastly improved compared to the corresponding homopolymerizations. Microstructurally, this copolymer is formed by complete consumption of DBO and partial incorporation of DBB. The remaining DBB forms tetrahydrothiophene (THT). These two odd and seemingly conflicting results could not be explained by “normal” or “inverse” PTC extraction mechanisms. Support of this new mechanism is given in the PTC polymerization of DBO with sodium sulfide in the presence of a catalytic amount of THT. The resulting polymer is of very high molecular weight and narrow polydispersity; it also does not contain tetramethylene sequences. Using this new mechanism, all results suggest the participation of cyclic sulfides either facilitates cyclic formation or enhance polymer reactivity as controlled by the length of the alkane dielectrophile.
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  • 96
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 191 (1990), S. 365-374 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This paper describes the key to successful metathesis polycondensation chemistry. Model compound reactions with styrene and styrene derivatives show that metathesis chemistry can occur exclusively if carbocation formation can be obviated through the proper choice of a Lewis acid free catalyst. Vinyl terminated oligo(octenylene)s were synthesized in this manner, which in turn were converted to polymers of high molecular weight.
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  • 97
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 191 (1990), S. 405-413 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: For the synthesis of symmetrical and unsymmetrical ethylidenediphenols the corresponding hydroxyphenylethanols (1a-c) were prepared by hydrogenation of hydroxyphenyl methyl ketones with hydrogen/Raney nickle or with lithium aluminium hydride. Condensations of the hydroxyphenylethanols with different phenols under the usual acidic conditions gave products formally resulting form transalkylations. Only the reaction of 1-(3-bromo-2-hydroxy-5-methylphenyl)ethanol (1c) with p-cresol gave the expected product 2d with 82% yield. Experiments with ethylidenediphenols showed that with acids in presence or absence of phenols cleavage and recondensations take place leading to products of formal transalkylation. Based on these results a method of synthesis was developed (the so-called “gaseous HCl-method”) leading to the desired ethylidenediphenols, as shown in the case of 4,4′,6-trimethyl-2,2′-ethylidenediphenol (2b).
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  • 98
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The potentiometric behaviour of two polyampholytes, poly[(methacrylic acid)-co-(2-dimethyl-aminoethyl metharylate)] and poly{(methacrylic acid)-co-[2-(methacryloyloxy)ethyltrimethyl-ammonium iodide]} is described. The dissociation constants of low-molecular-weight compounds modelling the structural units and diads of polyampholytes are reported, and effects of adjacentgroups on the potentiometric behaviour of the copolymers are discussed.
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  • 99
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Copolymers with intramolecular charge transfer interactions were synthesized by radical copolymerization of ω-(N-carbazolyl)alkyl methacrylates (where alkyl is propyl and butyl) with 2-(methacryloyloxy)ethyl 3,5-dinitrobenzoate. These copolymers are characterized by a dependence of the electronic absorption, the solubility and the density on the composition. The intramolecular degree of complexation depends on spacer length and exerts a maximum for the spacer with three methylene groups.
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  • 100
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Four enol esters with a styrene skeleton (3a-d) were synthesized in two steps from commercial products and polymerized or copolymerized with styrene as a comonomer. The polymers and copolymers (7 and 8) were characterized. They are stable up to 140°C and lose acetic acid upon heating. Chemical modifications, such as nucleophilic substitutions with cyanide ions or nucleophilic addition of butyllithium, were studied.
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