摘要:

AbstractAbove the certain temperature which depends on the composition of the polymer and usually exceeds 200°C the mechanism and regularities of polymer oxidation markedly change: the main reaction of peroxide radicals RO ˙2becomes decomposition with formation of low‐molecular radicals, activation energy decreases and the rate of oxygen consumption becomes directly proportional to the oxygen pre

ISSN:0003-3146    

DOI:10.1002/apmc.1983.051140101

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe tensile stress and temperature effects on the Polyethylene photooxidation kinetics have been investigated. Subjects are light stabilized and not stabilized high density Polyethylene films. The tensile stress used were 10% and 20% of the breaking stress. Temperatures of 50°C, 30°C, 5°C were realized in a chamber for an artificial climate with an irradiation source mercury ark lamp type

ISSN:0003-3146    

DOI:10.1002/apmc.1983.051140102

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractA report is given of recent studies into the influence of spectral energy distribution, irradiation intensity, moisture, oxygen pressure and specimen temperature on the results obtained during the accelerated weathering of unpigmented and pigmented polymers. In particular, a “radiation‐related spectral energy absorption” is defined and its possibilities for providing information on the sequence of the degradation processes that take place during weathering is discussed; in this respect it is possible to differentiate between the degradation of the polymer matrix by UV‐degradation, degradation by photocatalytic oxidation of the polymer when photoactive pigments are used and the protective action of high‐grade inorganic pigments. Finally, the possibilities for improving the process and equipment used in accelerated weathering are

ISSN:0003-3146    

DOI:10.1002/apmc.1983.051140103

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractOxidation of atactic polypropylene stabilized with phenyl‐naphthyl‐amine has been studied in the temperature range of 80–200°C. The induction period observed in the presence of inhibitor does not obey the Arrhenius law over all the temperature range s

ISSN:0003-3146    

DOI:10.1002/apmc.1983.051140104

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractPolymers of polystyrene and polyoelefine, containing covalently linked keto groups, are obtained. Polystyrene polymers are prepared by polymerization of styrene and unsatured ketones in the presence of polybutadiene while polyolefines are obtained by grafting unsatured ketones to the polymer. Films of copolymers, thus prepared, undergo photochemical degradation when exposed to natural and artificial light. The rate of degradation is considerably higher, as compared to the analogical polymers without keto groups, and it depends on the type and concentration of the ketone used. The reaction of degradation is propably mainly Norish II‐type which has the effect of decreasing the molecular weight of copolymers. That assumption is confirmed by the observed alteration in carbonyl and hydroxyl range ‐ 1720 cm−1and 3450 cm−1respectively in the polymer chains when they are irr

ISSN:0003-3146    

DOI:10.1002/apmc.1983.051140105

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe mechanism of synergism in mixtures of UV‐absorbers and radicals scavengers of peroxide decomposers is considered. The synergism is explained by diffusion of the antioxidant from the bulk of the polymer protected by UV‐absorber towards the surface layer where the photoreaction proceeds. It is also shown that it is possible to obtain the synergistic effects using additional stabilizing or nonstabilizing substances, which change the solubility of a given stabilizer and the mode of its distribution in polymeric mat

ISSN:0003-3146    

DOI:10.1002/apmc.1983.051140106

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe effect of the short wavelength range of the UV spectrum and the influence of elevated temperatures to the degradation of the plastics were measured in three different artificial weathering devices.

ISSN:0003-3146    

DOI:10.1002/apmc.1983.051140107

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe requirements are outlined which are made on artificial radiation sources for time accelerating weathering. The general radio‐physical data of an especially developed metal halide lamp are indicated, the so‐called Ultratest radiation, and are compared to the filtered Xenon radiation so far used in weathering machines.Information is given on specific radio‐physical and thermical conditions for certain comparing tests in machines at samples

ISSN:0003-3146    

DOI:10.1002/apmc.1983.051140108

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractBy means of differential IR‐spectroscopic analysis (“layer by layer”) of different types of polyethylene and additional testing of the mechanical behaviour of these materials the “material efficiency” of different natural and artificial weathering methods are discribed exemplary. The combination of IR‐spectroscopic analysis and microfractografic test results gives informations about the ageing progress in time and in the bulk of the polymer. In this respect the discussed material orientated method seems to be suitable for a quantitative estimation of the simulation quality of artificial weathering methods. Furthermore the method allows the comparative assessment of the degradation rate of different polymers in consideration of inhomogeneities as a result of production and/or processing (for example: the gradient of crystallinity) as well as the comparative estimation of natural weathering conditions (for example in respect of the material efficient period of weath

ISSN:0003-3146    

DOI:10.1002/apmc.1983.051140109

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractVestolen A 6016 and Vestolen P 5200 were acceleratedly weathered in a Xenotext 1200 and a Xenotest 450. By variation of operating conditions of Xenotest 1200 different spectral distributions in the UV region (with and without UV filter) were obtained. In Xenotest 450 polyethylene and polypropylene showed approximately the same process of damage, wheras polyethylene and polypropylene showed clear different “spectral sensitivities” in Xenotest 1200. The maximum of UV capacity which is possible in Xenotest 1200 enables a maximum of time accelerating effect ‐ also when light protecting systems are used ‐ but it does not admit a more exact evaluation of the quality of a light protecting formulation. The test of light protecting formulations based on UV absorber, HALS and combinations thereof showed, that evaluation can be very different and does not always conform with the results of out door wea

ISSN:0003-3146    

DOI:10.1002/apmc.1983.051140110

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY