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  • 1
    Electronic Resource
    Electronic Resource
    Posteffekt bei der Radiolyse von PolystyrolAuszugsweise vorgetragen auf dem Symposium über die Verwendung großer Strahlenquellen und von Beschleunigern in industriellen Prozessen der Internationalen Atomenergie-Organisation vom 18. bis 22. August 1969 in München. (1970)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 12 (1970), S. 185-196 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In polystyrene the major part of crosslinks is produced during irradiation in a “hot reaction”. 10% of the crosslinks are formed in a postreaction.A kinetic analysis of the experimental data showed the latter reaction to be first order. At larger storage times especially at higher temperatures the initial increase of crosslinks is followed by a decrease. This can only be explained if the crosslinks are formed during dissolution.We assume, that the posteffect is due to trapped cyclohexadienyl- and benzylradicals. The first order kinetics is ascribed to a transformation of cyclohexadienyl- to benzylradicals. By dissolution of the polymer after increasing storage time the reaction of cyclohexadienylradicals with benzylradicals, which leads predominantly to disproportionation, is replaced by recombination of two benzylradicals forming crosslinks. At higher temperatures and long storage times also benzylradicals must dissapear in the solid polymer by reactions not forming crosslinks.Additives like Anthracene and Naphthochinon suppress the posteffect.Based on the experimental results a reaction mechanism for the formation of crosslinks during irradiation and in the postreaction is proposed.
    Notes: Der Hauptteil der im Polystyrol radiolytisch erzeugten Kettenvernetzungen entsteht während der Bestrahlung im festen Polymeren. Es konnte jedoch gezeigt werden, daß nach Bestrahlungsende das Reaktionsgeschehen noch nicht absgeschlossen ist, sondern eine Postreaktion stattfindet, über die etwa 10% der Vernetzungen gebildet werden.Die kinetische Analyse unserer Ergebnisse ergab, daß es sich hierbei um die Aufeinanderfolge zweier Teilreaktionen handelt, deren erste, zu Vernetzungen führende, dem Reaktionsgesetz erster Ordnung gehorcht. Dabei muß angenommen werden, daß die Vernetzungen der Postreaktion erst bei der Quellung des bestrahlten Polymeren im Lösungsmittel entstehen.Das Reaktionsgeschehen wird so gedeutet, daß in der ersten Teilreaktion eine Umwandlung von Cyclohexadienylradikalen in Benzylradikale erfolgt, für die bei der Quellung die Möglichkeit der Vernetzungsbildung besteht. Im Falle höherer Lagerzeiten und beim übergang zu höherer Temperatur muß für diese Benzylradikale jedoch eine nicht zu Vernetzungen führende Konkurrenzreaktion existieren. Als solche wird Doppelbindungsbildung in Betracht gezogen.Durch die Additive Anthracen und Naphthochinon wird die Postreaktion bei der angewandten Dosis unterdrückt. Dies führen wir zurück auf das Quenchen von angeregten Zuständen bzw. das Abfangen von Radikalen, insbesondere von thermischen H-Atomen.Gestützt auf die experimentellen Ergebnisse wird ein Reaktionsmechanismus für die Ausbildung von Kettenvernetzungen während der Bestrahlung und im Posteffekt gegeben.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1970.050120115
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  • 2
    Electronic Resource
    Electronic Resource
    Toxicity of polyurethane-derived oxidative thermal decomposition productsAbbreviations: GSH = reduced glutathione; MDA = 4,4′-diaminodiphenylmethane; MDI = 4,4′diphenylmethane diisocyanate; NADPH = reduced nicotinamide-adenine; dinucleotide phosphate; UDP = uridine-5′-diphosphate (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Fire and Materials 6 (1982), S. 96-98 
    Details
    ISSN: 0308-0501
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fam.810060210
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  • 3
    Electronic Resource
    Electronic Resource
    Simulation of insulator charging by a narrow electron beam (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 22 (1994), S. 115-119 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: We are dealing with the problem of the charge distribution within an insulator (present application: SiO2) which is bombarded by a narrow electron beam. The electron trajectories within the sample are simulated via a single diffusion Monte-Carlo method. A mathematical model is proposed for the potential and the charge density. The development of an electric field, a potential and the broadening of the incident beam are taken into account. These two last distributions appear to have a prominent effect. It is shown that the charge distribution tends to a double layer; the shape and thickness of positive and negative distributions are given.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740220128
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  • 4
    Electronic Resource
    Electronic Resource
    Photorearrangements of hydrocarbon polymers with pendant double bondsPresented at the Division of Polymer Chemistry at the ACS/CSJ Chemical Congress, Honolulu, Hawaii, April 1979. (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 18 (1980), S. 2543-2560 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A study was made of the microstructural changes that occur in ultraviolet irradiation under vacuum of thin films of 1,2-poly(cis-1,4-hexadiene) (CHD), 1,2-poly(trans-1,4-hexadiene) (THD), 1,2-poly(trans-1,3-pentadiene) (TPD), equibinary (1,2,-1,4) polybutadiene (EB), and equibinary (3,4-1,4) polyisoprene (EI). These polymers - all containing pendant double bonds - undergo important photoinduced loss of unsaturation, presumably through cyclization of the double bonds, by analogy to the previously reported photocyclization of 1,2-polybutadiene (VB) and 3,4-polyisoprene (VI)films. For the equibinary polymers, which contain internal as well as external (or pendant) double bonds, the loss of unsaturation is considered to involve photocyclization of 1,2-1,4 and 1,2-1,2 dyads in EB and of 3,4-1,4 and 3,4-3,4 dyads in EI. Accompanying thecyclization process in CHD, THD, and TPD is a direct photochemical cis-trans isomerization of —CH=CH—double bonds analogous to that originally noted for 1,4-polybutadiene. The photorearrangements in the above polymers with pendant double bonds were compared to the corresponding thermally induced rearrangements reported previoulsy;for VB and VI, in particular, the thermal, photo-and radiation-induced cycli-zations were found to be very similar, possibly having a common nonradical, nonionic mechanism involving excited double bonds.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.170180813
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  • 5
    Electronic Resource
    Electronic Resource
    Singlet oxygenation of 1,2-poly(1,4-hexadiene)s (1979)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 3751-3757 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The microstructural changes that occur in cis and trans forms of 1,2-poly(1,4-hexadiene) during methylene blue-photosensitized oxidation were examined by infrared (IR) and 13C-NMR spec-troscopy. The singlet oxygenation of these polymers yielded the expected allylic hydroperoxides accompanied by double bond shifts to new vinyl and trans-vinylene double bonds. The photosensitized oxidation exhibited zero-order kinetics; the relative rates for the cis- and trans-1,2-poly(1,4-hexadiene)s were approximately 3.8:1.0.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1979.170171130
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis of carbonate-containing high temperature poly(arylene-siloxanylenes) (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 20 (1982), S. 1-13 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method for the first synthesis of high molecular weight carbonate-containing siloxanylene polymers was successfully developed. The procedure covered the preparation and polymerization of pure carbonate-containing bis-silanols which included bis(4-hydroxydimethylsilylphenyl)-carbonate, bis[4-(1-hydroxy-1,1,3,3-tetramethyldisiloxanyl)-phenyl] carbonate, and their meta analogs. Because conventional siloxane polymerization methods, such as the heterocondensation of bis-silanols with diaminosilanes or homocondensation reactions catalyzed by alkali reagents, decomposed carbonate linkages, a new polymerization technique that involved the use of phosgene was used. The procedure was both facile and effective in the polymerization of other arylene bis-silanols.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.170200101
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  • 7
    Electronic Resource
    Electronic Resource
    The sol/gel contribution to the behavior of γ-irradiated poly(vinylidene fluoride) (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 43 (1991), S. 535-541 
    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: Poly(vinylidene fluoride) films were γ-irradiated in the dose range of 1-20 Mrad, resulting in up to 74% gel. The irradiated polymer undergoes both crosslinking and chain scission, about 5 : 3 events, respectively. Swelling measurements indicate an increasing crosslink density with the gel content, already at the lower doses. Thermal analysis of the gel fraction and the unextracted irradiated samples shows that although crosslinking affects the crystallization, degree of crystallinity, and the melting characteristics, the behavior of the crosslinked material is predominantly controlled by the extractable sol fraction which consists of the more mobile original chains, branched chains, and degraded ones. The crosslinks, already at low density, retard the development of ordinary crystalline polymer morphology.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070430314
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  • 8
    Electronic Resource
    Electronic Resource
    Characterization of cured polystyrylpyridine by model compoundsPresented at the 1979 Pacific Conference on Chemistry and Spectroscopy in Pasadena, California on 10-12 October 1979. (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 1975-1987 
    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: The crosslinking or curing reaction of polystyrylpyridine (PSP) has been studied by means of thermal reactions of its model compounds. Compounds 2,6-distyrylpyridine, 4-stilbazole (4-styrylpyridine), and deuterated 4-stilbazole were pyrolyzed at 200-325°C both in air and under vacuum in a sealed tube. The major pyrolysis products were diarylethane and stilbene, and were characterized by gas chromatography-mass spectrometry. Major dimeric products were naphthalene or quinoline derivatives. Mechanisms for the pyrolysis are suggested, and a crosslinked structure for cured PSP is proposed based on the thermal reaction products of model compounds.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1981.070260621
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  • 9
    Electronic Resource
    Electronic Resource
    Low dose γ-irradiation of some fluoropolymers: Effect of polymer chemical structure (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 783-795 
    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: The effect of low dose (1-20 Mrad) γ-irradiation on five fluoropolymers (PVF, PVDF, ETFE, FEP, PFA), differing in fluorine content and chain structure, was studied. The radiation effect, reflected by changes in thermal and mechanical properties, as well as NaOH etched surface morphology, was investigated. The main chain structure was found to predominate the irradiated polymers' behavior. The tensile strength of PVF and its resistance to etching increased with radiation dose, while its degree of crystallinity and melting temperature decreased. These changes were correlated with network formation by irradiation and by the incorporation of crosslinked segments into the crystalline phase during recrystallization. Solvent extraction of PVDF (no solvents were found for the other fluoropolymers) revealed increased gel formation with increasing dose. The degree of crystallinity and the tensile strength dependence on radiation dose for PVDF and ETFE reflected the competition between crosslinking and chain scission events. FEP and PFA undergo predominantly chain scission accompanied by reduction of their mechanical properties. PFA even exhibited an increase in both its melting temperature and degree of crystallinity, stemming from a massive degradation process forming shorter chains. Chemical mechanisms are discussed in an attempt to correlate the irradiation effects with the polymers' chain structure.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070450504
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  • 10
    Electronic Resource
    Electronic Resource
    Thermal expansion of epoxy-resin/particle composites - a size effect (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 18 (1980), S. 217-226 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermal expansion of epoxy-resin (Epikote 828)/particle composites has been measured in the range 77 to 450 K. The fillers used were Cu spheres (seven sizes from 5 to 150 μm diameter) and glass ballotini spheres (three sizes from 3.5 to 200 μm diameter). The volume concentrations used were 0.3 and 0.5 for Cu and 0.3 for glass. The experiments show that the addition of filler raises the glass transition temperature Tg, especially for fine particles. Below the normal value of Tg the thermal expansion is independent of particle size while above Tg the expansion is considerably smaller for samples containing the smaller particles. The effect is more pronounced for Cu than for glass filler. In addition a rapid heating rate reduces the expansion for specimens containing smaller particles but it does not effect the expansion for those containing large particles. The results, which are discussed in the light of the work of other authors, suggest that the addition of particles increases Tg by changing the nature of the polymer not only immediately at the particle surface but also for a considerable distance into the polymer itself. This probably occurs because the epoxy bonds strongly to the particles and this inhibits segmental rotations of the polymer even at considerable distances from the particle surface.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.180180204
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