Thermal ageing and accelerated weathering of HMSPP: structural and morphological studies

Abstract

This work focuses of the influence of weathering factors UV radiation, humidity, and temperature on the structure and morphology poly(propylene) (PP) with high melt strength (HMSPP), also called poly(propylene) modified by irradiation. The HMSPP was prepared from isotactic poly(propylene) (iPP) in presence of acetylene at 110 kPa pressure and irradiated with g of 60Co at doses of 5, 12.5 and 20 kGy. It has been observed that HMSPP deteriorates in the weathering and thermal resistance, and the long-term stability of HMSPP, beyond substantial color changes. The aged samples were characterized by infrared spectroscopy (FTIR), optical microscopy (OM) and differential scanning calorimetry (DSC). The optical microscopy shows different mechanisms on thermal and artificial weathering ageing. The ageing result under elevated temperature in HMSPPs exposed surfaces follows the order: HMSPP 20>12.5>5 kGy>iPP. The intense crack formation in surface exposed justifies thermooxidative degradation.