Degradação foto-oxidativa da borracha deEPDM vulcanizada

AUTOR(ES)

Marile Guzzo

DATA DE PUBLICAÇÃO

1990

RESUMO

ln this thesis the photo-oxidative degradation of dicumyl peroxide vulcanized EPDM rubber was studied. This rubber is an ethylene/propylene/ ethylidene norbornene terpolymer. Due to its random structure it is an amorphous material. The first part of the thesis describes the photo and thermal oxidation and the photo stabilization of thin films. The oxidation products formation kinetics was followed by infrared spectroscopy observing the absorption changes at 1710 cm (v c=o). Vulcanized films show a higher degradation rate than non-vulcanized films. Also the peroxide concentration used in the vulcanization affects the degradation rate up to a certain value. An stabilization system combining a photo-stabilizer (Tinuvim 327) and an antioxidant (Irganox 1076) showed a strong effect in the reduction of the photo-oxidation rate. Irganox 1076 showed a good stabilization performance for the thermal-oxidation of vulcanized EPDM. In the second part of this thesis we studied the changes in the mechanical properties and the thermal analysis of vulcanized rubber with and without filler as a function of photochemical aging. By means of the mechanical properties measurements, according to ASTM D-412 it was observed that the elongation at break and the stress at failure change very liltle as a function of irradiation time for the vulcanized rubber without filler. However, for the filled rubber (52.9% of tri-hydrated alumina) drastic changes of the mechanical properties are observed. Thermal analysis data showed that, with or without filler the thermal properties of the vulcanized rubber are not affected by the photachemícal aginlg. The fracture surface of filled vulcanized EPDM samples was analyzed by Scanning Electron Microscopy. This study showed that the fracture process is affected by photochemical aging. The filler migration during aging was also confirmed by this technique.

ASSUNTO(S)

elastomeros polimeros e polimerização borracha

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