Thermooxidative degradation of high melt strength polypropylene (HMS-PP)
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2010
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MEETING OF THEN IONIZING RADIATION AND POLYMERS SYMPOSIUM, 9th
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Modified properties of polyolefins, including iPP, must find an explanation in terms of the basic irradiation processes: crosslinking , branching and degradation. HMS-PP in pellets form was synthesized by the gamma irradiation (60Co) of PP under a crosslinking atmosphere of acetylene with doses of 5, 12.5 and 20 kGy. After irradiation the samples were submitted to a thermal treatment at 90 °C for 1h to eliminate residual radicals [1,2]. A common approach for characterizing ageing response in a more practical time frame is to conduct accelerated ageing tests at temperature above the expected service limits. The thermal stability of the HMS-PP was evaluated after thermal ageing of dumbbell samples using a stove at temperature of 120 °C, in presence of air at different periods of time. The surface of PP , pristine and modified, (i.e., irradiated), was studied using optical microscopy (OM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X ray scattering. The effects of elevated temperature ageing were evaluated in HMS-PPs exposed surfaces according to the order: HMS-PP 20 >12.5 >5 kGy, showing intense crack formation in all the exposed surfaces due to thermooxidative degradation.
The results were compared with previous work [1] where no evidence of thermoxidation was reached, exposition applied test at temperature of 90°C. The new condition is more conclusive about the effect of the thermooxidative degradation in the irradiated materials.
Como referenciar
OLIANI, W.L.; PARRA, D.F.; LIMA, L.F.P.C.; LUGAO, A.B. Thermooxidative degradation of high melt strength polypropylene (HMS-PP). In: MEETING OF THEN IONIZING RADIATION AND POLYMERS SYMPOSIUM, 9th, October 25-29, 2010, Maryland, USA. Abstract... Disponível em: http://repositorio.ipen.br/handle/123456789/21285. Acesso em: 30 Dec 2025.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.