reprocessing cycles, being practically insignificant from the sixth reprocessing cycle. Therefore, from the point of view of its thermal stability, the material could be recycled more or less times depend- ing on the final requirements. A similar behaviour was observed for the samples reprocessed by both injection and extrusion.
The thermal stability of the reprocessed materials can be eval- uated in an easy and fast manner by determining its flow index. Tables 2 and 3 show the flow index values for all the injection and extrusion molding cycles, respectively. As shown, the flow index increased with the number of reprocessing cycles for both types of reprocessing. This result was expected since an increase in flow index is indicative of small molecular weights and, it was already observed, in both types of reprocessing, that the molecular weight decreased with the number of reprocessing cycles. Similar results have been obtained by other authors. For example, Liu et al. (2000) showed that during the reprocessing of injection-molded polycarbonate, the flow index increases slightly but continuously, through the first four cycles, stabilizing thereafter. Chrysostomou and Hashemi (1996) have shown that flow index values increase slightly from the virgin material to the five-time recycled mate- rial. This slight increase in fluidity of the reprocessed materials was attributed to the decrease in the molecular weight of the polymer, arising from the reduction in polymeric chain lengths caused by degradation during processing.