An investigation into the fracture behaviour of ethylene propylene impact copolymers

Injection moulded copolymer specimens containing between 6 to 11% ethylene were impacted using the drop weight method at 23°C and −20°C. Their response to the impact event was analysed in terms of failure mechanisms by considering their initiation and propagation energies at the respective temperatures. At −20°C, the results indicated that the multiple shear yielding toughening mechanism is predominant whereas room temperature tests show evidence of multiple crazing behaviour. The peak force sustained by the specimens decreased with the testing temperature.