Thermo‐oxidative degradation behavior of recycled polypropylene

This study has been carried out to mimic the thermo‐oxidative degradation of polypropylene (co‐PP) during service life and recycling. Injection molded specimens were heat aged at 130°C for different times up to maximum of 300 h to simulate the degradation of co‐PP during the service life. These aged specimens were mixed with stabilizers in internal mixer and again heat aged up to 300 h. A small increase in melt flow rate (MFR) value was observed for aged co‐PP but it showed large increase after recycling. The presence of carbonyl peak at 1713 cm⁻¹ confirmed the oxidation of co‐PP during aging and it increases with aging time. Carbonyl index (CI) is increased in recycled sample with aging, whereas oxidation induction time (OIT) decreased. The stabilizers used during reprocessing are quite effective in controlling the thermo‐oxidative degradation of the polymer during processing and aging. The thermogravimetric analysis shows that the onset of degradation temperature starts at low temperature for recycled sample as compared to virgin co‐PP. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011