Photodegradation and stabilization of polypropylene, polyethylene and their copolymers under accelerated weathering

The photodegradation and stabilization of polypropylene (PP), polyethylene (PE) and their copolymers (EPT 30U and EPT 30R) was investigated by addition of two different stabilizers: Chimassorb944 (C) and Tinuvin770 (T). The photoirradiation of polymer films was carried out under accelerated condition (UV irradiation λ ≥290nm) at 60℃ for different time intervals. The resulting degradation was estimated by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and optical microscopy. Thermal decomposition kinetics of copolymers was also studied and compared with polypropylene. Extent of degradation was evaluated by monitoring changes in functional groups (carbonyl and hydroxyl), thermal changes and surface morphology. It was observed that extent of photodegradation was reduced in all irradiated stabilized polymer samples, but polyethylene sample containing 0.5wt% Chimassorb 944 (C) showed best stabilization as compared to the rest.