SANTOS, J. A. B.; http://lattes.cnpq.br/9277814890785373; SANTOS, João Antonio Belmino dos.
Resumen:
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.
