To determine thermal ageing properties, the dumbbell-shaped specimens were placed in an oven equipped with an air circulating system at a test temperature of 100 C for 48 h, according to ASTM:D573-04(2010). The aged specimens were then measured for tensile properties. The changes in tensile strength and hardness after thermal ageing were used to determine thermal ageing resistance. The retention in each property was evaluated according to the following equation