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  • Articles: DFG German National Licenses  (38)
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  • Articles: DFG German National Licenses  (38)
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  • 1
    Electronic Resource
    Electronic Resource
    Comparison of simultaneous and preirradiation grafting of methyl methacrylate onto a porous membrane (1991)
    s.l. : American Chemical Society
    Chemistry of materials 3 (1991), S. 987-989 
    Details
    ISSN: 1520-5002
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/cm00018a002
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  • 2
    Electronic Resource
    Electronic Resource
    Introduction of a high-density chelating group into a porous membrane without lowering the flux (1991)
    s.l. : American Chemical Society
    Industrial & engineering chemistry research 30 (1991), S. 2234-2237 
    Details
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ie00057a028
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  • 3
    Electronic Resource
    Electronic Resource
    Durability of radiation-sterilized polymers, XIIIPart XI cf. lit.6.. The effects of nucleating agent on the oxidative degradation of poly(propylene-co-ethylene) (1990)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 174 (1990), S. 131-140 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die 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.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1990.051740111
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  • 4
    Electronic Resource
    Electronic Resource
    Radiation grafting of hydrophilic monomers onto poly(4-methylpentene-1), IIPart I, cf. lit.1.. Grafting of long chain monomers and physical properties of the grafted films (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 152 (1987), S. 159-168 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die strahleninduzierte Pfropfung von 2-Hydroxyethylmethacrylat (HEMA) und Methoxytetraethylenglycolmethacrylat (M4G) auf Poly(4-methylpenten-1) (TPX) wurde untersucht. Die Pfropfungsgrade erhöhten sich mit zunehmender Vorbestrahlungsdosis, Pfropfungstemperatur und Monomerkonzentration. Die Pfropfungsgeschwindigkeit ist abhängig von der Kettenlänge der Monomeren; sie nimmt mit wachsender Kettenlänge ab. Bei Bestrahlen der Filme mit Elektronenstrahlen anstelle von γ-Strahlen waren die Pfropfungsgrade höher. Die Zugfestigkeit der gepfropften Filme im trockenen Zustand stieg mit zunehmendem Pfropfungsgrad an, während die Bruchdehnung abnahm. Dagegen nahmen die Zugfestigkeit und die Bruchdehnung im nassen Zustand mit wachsendem Pfropfungsgrad ab, da Wasserstoffbrückenbindungen zwischen den aufgepfropften Ketten durch die Wasseraufnahme der Filme fehlten.
    Notes: Radiation grafting of 2-hydroxyethyl methacrylate (HEMA) and methoxytetraethyleneglycol methacrylate (M4G) on low crystallinity poly(4-methylpentene-1) (TPX) has been investigated. Grafting yield increased with increasing pre-irradiation dose, grafting temperature, and monomer concentration. Grafting rate depends on length of molecular chain in the monomers and decreases with increasing chain length. The grafting yields of electron beam irradiated samples were higher than those of γ-irradiated ones because of higher radical concentration. Tensile strength of the grafted film in the dried state increased and the elongation at break decreased with increasing degree of grafting. On the other hand, in the wet state, the tensile strength and elongation at break decreased with increasing the degree of grafting due to the lack of hydrogen bonds between the grafted chains caused by increased water absorption.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051520114
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  • 5
    Electronic Resource
    Electronic Resource
    Durability of radiation sterilized polymers, V. Depression of molecular weight and melting point by oxidation (1986)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 143 (1986), S. 75-83 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Molekulargewicht und Schmelzpunkt von durch Bestrahlung sterilisiertem Polypropylen wurden untersucht. Bestrahlung von Polypropylen mit einer Dosis von 2,5 Mrad reduzierte das Molekulargewicht um ein Drittel, wobei die Abnahme des Molekulargewichts bei Bestrahlung im Vakuum viel kleiner war als bei Bestrahlung in Luft. Der Schmelzpunkt wurde mit zunehmender Dosis zu niedrigeren Temperaturen verschoben. Dies stimmt mit der Abnahme des Molekulargewichts gut überein. Im Differentialkalorimeterdiagramm erschien bei niedrigerer Temperatur ein neuer Peak, dessen Intensität sich mit zunehmender Dosis erhöhte. Bestrahltes Copolypropylen, das einen niedrigeren Kristallinitätsgrad als bestrahltes Homopolypropylen hatte, war im Vergleich zu diesem stabiler in den mechanischen Eigenschaften, jedoch wurden sowohl im Copolypropylen als auch im Homopolypropylen durch die Bestrahlung Bindungen gespalten. Hieraus wurde gefolgert, daß das Verhältnis von amorphen zu kristallinen Bereichen in den Polymeren einen großen Einfluß auf die mechanischen Eigenschaften von bestrahltem Polypropylen hat.
    Notes: Molecular weight and melting point of polypropylene degraded by irradiation sterilization were measured. The sterilization of polypropylene with a dose of 2.5 Mrad reduces its molecular weight by one third. The decrease in molecular weight of the polypropylene irradiated in vacuum was far smaller than that for samples irradiated in air. The melting point was shifted to lower temperatures with increasing dose. This corresponds well to the decrease in molecular weight. For irradiated copolypropylene, a new peak appeared in the differential scanning calorimetry diagram at a lower temperature and its intensity increased with the dose. Copolypropylene, the crystallinity of which is lower than that of homopolypropylene, was more stable in the mechanical properties compared to irradiated homopolypropylene. However, scission by irradiation occurred in copolypropylene as well as in homopolypropylene. Thus, it was concluded that the ratio of amorphous and crystalline parts in the polymer has an important influence on mechanical properties of irradiated polypropylene.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1986.051430107
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis of hydrophilic elastomers by radiation grafting (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 152 (1987), S. 149-158 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die strahleninduzierte Pfropfung von Acrylsäure auf Ethylen-Propylen-Kautschuk (EPR) wurde untersucht. Es wurde gefunden, daß die Pfropfungsgrade bei Zugabe von Alkohol (Methanol und Isopropanol) abnahmen und die Bildung der Homopolymeren verzögert wurde. Bei Zugabe von Alkohol fand Pfropfung auch im Innern des Filmes statt. Die Pfropfungsgeschwindigkeit war sehr stark vom Propylengehalt im EPR abhängig. Die Pfropfungspolymerisation fand bei kleinen Propylengehalten, z. B. bei 22%, leichter statt. Die Stabilität der Radikale mit niedrigeren Propylengehalten war höher als die der anderen. Die Wasseraufnahme der gepfropften Filme stiegen linear mit dem Pfropfungsgrad an.
    Notes: Radiation grafting of acrylic acid (AAc) onto ethylene-propylene rubber (EPR) to obtain hydrophilic elastomers has been investigated. It was found that by addition of alcohol (methanol and 1-propanol) into water as solvent for grafting the degree of grafting increased and formation of homopolymer was retarded. The grafting by addition of alcohol occurred even in deeper portions of the film compared with no addition of alcohol. Grafting rate differed largely with propylene contents in the EPR. Graft polymerization occurred easily in EPR of lower propylene contents such as 22%. Before introducing AAc in grafting the stability of EPR radicals of lower propylene contents was higher in comparison with other components. Water absorption of EPR increased linearly with increasing grafting yield.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051520113
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  • 7
    Electronic Resource
    Electronic Resource
    Kinetic study of preirradiation grafting of acrylic acid onto poly(tetrafluoroethylene-perfluorovinyl ether) copolymer (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 597-604 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A kinetic study has been made on the preirradiation grafting of acrylic acid (AAc) onto poly(tetrafluoroethylene-perfluorovinyl ether) (PFA) film. The effect of grafting conditions was investigated. The dependences of the grafting rate on preirradiation dose and monomer concentration was found to be of the order of 0.5 and 1.3, respectively. The final degree of grafting was found to increase with dose and monomer concentration. However, it decreases as the grafting temperature increase. The overall activation energy for the graft polymerization was calculated from Arrhenius plots to be 5.6 kcal/mol. The activation energy for this grafting system was found to be independent of preirradiation dose used in the range from 10 to 100 kGy. The relationship between the grafting rate and film thickness gave a negative first-order dependence. The results suggest that the grafting proceeds by radical mechanism with bimolecular termination of growing chain radicals. It was reasonable concluded that this grafting proceeds from the surface to the center of film with progressive monomer diffusion through the grafted layer which swells in the monomer solution.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1984.170220309
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  • 8
    Electronic Resource
    Electronic Resource
    Radiation-induced copolymerization of vinylene carbonate with methyl trifluoroacrylate (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 3417-3421 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Copolymerization of vinylene carbonate (VCA) with methyl trifluoroacrylate (MTFA) was carried out by gamma rays from 60Co at dose rates of 1 × 105 rad/h to 1 × 106 rad/h, temperatures of 0°C to 75°C, and molar ratios MTFA/VCA of 30/70 to 90/10 in the monomer mixture. By irradiation, VCA reacted with MTFA to give a white powder copolymer with low molecular weight. The copolymerization rate has a maximum at a concentration of 70 mol % VCA, and is proportional to the 0.92 power of dose rate. The apparent activation energy was 1.3 kcal/mol. Equimolar copolymer was obtained at molar ratio MTFA/VCA of 50/50 to 10/90. The reactivity ratios of both monomers, VCA and MTFA, were determined to be r(VCA) = 0.3 and r(MTFA) = 0.07, respectively.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1984.170221157
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  • 9
    Electronic Resource
    Electronic Resource
    Iodine-initiated, solid-state copolymerization of tetraoxane with 1,3-dioxolane in the presence of methylal. II. Properties of copolymer obtained by beaker-scale copolymerization (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 723-733 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In order to elucidate the copolymerization mechanism, the properties of the copolymer obtained by the iodine-initiated copolymerization of the tetraoxane-1,3-dioxolane-methylal system have been studied using gas chromatography, microscopy, scanning electron microscopy, differential scanning calorimetry, and gel permeation chromatography. From the behavior of the thermal stability and gas chromatography of the reaction mixture, it was found that reactivity of 1,3-dioxolane with active center is larger than that of tetraoxane, i.e., more than 90% 1,3-dioxolane is consumed at an early stage of the polymerization. The results obtained by microscopy, DSC, and GPC of the copolymer suggested that the copolymerization proceeds from the surface to the center of the tetraoxane crystal as if it were a core model. It was also suggested that the heterogeniety in copolymer properties can be explained not only by heterogeneous dispersion of 1,3-dioxolane in tetraoxane crystal, but also by the difference of reactivity of 1,3-dioxolane with the active center.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070210313
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  • 10
    Electronic Resource
    Electronic Resource
    Iodine-initiated, solid-state copolymerization of tetraoxane with 1,3-dioxolane in the presence of methylal. IV. Fractional dissolution of copolymer (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 749-759 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A fractional dissolution on the oxymethylene copolymer obtained by the iodine-initiated, solid-state copolymerization of the tetraoxane-1,3-dioxolane-methylal system has been carried out using a mixed solvent which consists of tetrachloroethane, phenol, and cyclohexanol. On the fractional dissolution, the oxymethylene copolymer was divided mainly into two parts: one was the copolymer containing a larger amount of ethylene oxide unit in its main chain and having lower molecular weight; the other was copolymer containing a smaller amount of ethylene oxide unit and having a higher molecular weight. It was reasonably concluded that in this copolymerization system, the reaction proceeds from the surface to the center of the tetraoxane crystal to give a divided copolymer due to the heterogeneous properties such as copolymer composition and molecular weight.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070210315
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