Effect of Recycled HDPE with Pro-oxidant on the Photodegradation of HDPE Film

Abstract

Stability and photodegradation studies of HDPE film blended with recycled HDPE, with and without pro-oxidant, were carried out by subjecting the film to accelerated UV exposure up to 144 hours. Two types of recycled HDPE were used; one containing pro-oxidant (recycled degradable HDPE – RDH) and the other without pro-oxidant (recycled standard HDPE – RSH). The loading levels of recycled HDPE were varied from 10 to 30% by weight. The degradation behaviour of the film was then evaluated based on elongation at break, carbonyl index and oxidative induction time (OIT). The results obtained show that the degradation rate of HDPE films, with different levels and types of recycled HDPE (RSH and RDH), were directly correlated to UV exposure time. However, more pronounced changes in elongation at break and carbonyl index were observed, in particular the HDPE film blended with RDH. At 30% loading of RDH, the film degraded at a higher rate compared with film containing the same level of RSH. This suggests that HDPE blended with RDH even at a low loading of 10% could promote degradation of the film. The remaining pro-oxidants in RDH induced the formation of free radicals in the HDPE chain and accelerated the degradation process.