Deformation and impact toughening behaviour of compatibilised blends of polyamide 6 and copoly(ethylene/propylene/diene)

Blends of polyamide 6 (PA6) and copoly(ethylene/propylene/diene) (EPDM) compatibilised with maleic anhydride have been injection moulded. Drop weight Charpy impact tests were used to determine the impact behaviour of the blends. The results showed that the impact energy of the blends initially tends to decrease with increasing striker speed, followed by a levelling off at higher impact velocities. A sharp brittle-tough transition was found on the steady state impact energy ν. EPDM content curves. Scanning electron microscopy revealed that cavitation of the rubber particles occurs in the slow crack growth zone of the blends having EPDM ≤ 12-9 vol.-%. However, shear yielding of the matrix was observed in the slow crack growth zone of the blends containing EPDM > 12-9 vol.-%. Thus the blends having EPDM > 12-9 vol.-% exhibited good impact toughness. In addition, the ratio between the area of the slow crack growth zone and the entire fracture surface of the blends was determined. The relationship between the steady state values of the impact energy and the area ratio is discussed. © 1996 The Institute of Materials.