SUSCEPTIBILITY OF ENHANCED ENVIRONMENTALLY DEGRADABLE POLYETHYLENE TO THERMAL AND PHOTOOXIDATION

LDPE films containing a biodegradable starch filler, a pro-oxidant formulation and a thermal stabilizer were subjected to accelerated thermal ageing in an air environment at 100-degrees-C and 60-degrees-C (simulating composting temperatures) and to UV ageing in a weatherometer. Degradation was monitored by chemiluminescence (CL), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), high-temperature size-exclusion chromatography (HTSEC) and scanning electron microscopy (SEM). Volatile degradation products were detected by gas chromatography-mass spectrometry (GC-MS). All these techniques indicated that the samples were susceptible to thermal and photo-oxidation, particularly the former. LDPE containing corn starch as the sole additive was found not to be degraded, suggesting that the pro-oxidant formulation was responsible for the observed degradation.