Reprocessamento do PEBD através do uso de um pró-oxidante.

Abstract

The chemical and physical changes caused by degradation processes frequently lead to a reduction in product lifetime and, as a consequence, the disposal of components in landfills. The use of recycling procedures can be a good alternative in some situations, but in the case of polyethylene the recycling is a technological procedure relatively complex due to the formation of crosslinks when this polymer is exposed to the ultraviolet radiation. The main consequence of crosslinking is the loss of flow properties, with a high decrease in melt flow index. The aim of this work was to analyse the behaviour of low density polyethylene exposed to UV radiation in the laboratory (in an attempt to simulate a recycled material). The main idea was to reverse die crosslinking effects by using attapulgite, a mineral filler with very strong oxidant effects. The samples were compression moulded and, after photodegradation, they were mixed with attapulgite and exposed to high temperature in an electric oven. The results indicated that the procedure was very effective since the samples showed a melt flow index recovery after the thermal treatment. The phenomena of chain scission and crosslinking were shown to be dependent on the type of exposure. In photodegraded samples chemical crosslinkings were the predominant reactions whereas chain scissions took place when the samples were exposed to thermal degradation.