Influência de estabilizantes no envelhecimento de compósitos de polipropileno/atapulgita.

Abstract

Polyolefins are plastics largely used in the automobilistic, eletro-electronic and domestic appliances industries. One of the disadvantages of these materials is that their resistance to weathering is poor. Mineral fillers are commonly added to these plastics as a means of lowering costs and tayloring its properties to the demands of use. In the present work, the effect of addition of different stabilizers (TINUVIN 327, 791-FF and a 1:1 combination of 327/791-FF) on mechanical, thermal and thermomechanical properties of polypropylene (HF-36) and of a PP/Attapulgite composite at 5% w/w filler content subjected to natural and thermal ageing were investigated. The results showed the ultra-violet satbilizer (TINUVIN 327) was unable to prevent thermal degradation during processing and that best results were obtained either with the (UV/thermal) TINUVIN 791-FF stabilizer or with the system TINUVIN 327/791-FF where both thermal and light stabilization was effective. Attapulgrtc was shown to accelerate uv degration by weathering on the initial stages but ended up by having a protective effect at longer exposure times. Thermal degradation was accelerated by attapulgite addition, but the addition of the TINUVIN 791-FF and the combination TINUVIN 327/TINUVIN 791-FF stabilizers lowering this effect.