Foto-oxidação de polipropileno sob tensão mecanica

AUTOR(ES)
DATA DE PUBLICAÇÃO

1991

RESUMO

There are few works on polymer degradation caused by two or more initiation ways. There are some works on chemo-mechanical (ozone and load), in thermomechanical and very few works on photomechanical degradation. In this work we studied the photo-oxidation of isotactic polypropylene films under load. These films were low and highly oriented, and its formulations include photoprotecting agents or not. The irradiations were carried out with an UV source and a solar simulator, and the load applied was static or dynamic. The oxidation reactions were followed by carbonyl index determinations from IR spectra and by mechanical testing. The results indicate that the photolytic effects can be associated to mechanical load, to the polymer morphology, to the extent of oxidation reactions and to the intensity of the UV source. In the earlier stages of the photo-oxidation the static load can act as a protector against oxidation, in a similar manner as observerd with highly oriented samples. Mechanical testing under UV irradiation results in a decrease of the yield stress of the polymer. The photooxidation under load also affects the mechanical properties of polypropylene (modulus, yield point and stress/strain at break).

ASSUNTO(S)

polimeros e polimerização quimica organica

ACESSO AO ARTIGO

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