Fracture toughness of elastomer-modified polypropylene

The fracture toughness of impact modified polypropylene (PP) with impact modifier (IM) content Lip to 30 wt% was measured under quasi-static and impact rates of loading. Three types of IMs,were employed in this work; which,were all PP/PE based copolymers. Under quasi-static rate of loading, the fracture toughness for blends containing 30 wt% of I were measured using the specific essential,work of fracture (w(e)) and the J-integral via the locus method (J(c)). Both methods gave similar values of fracture toughness. Furthermore, the type of impact modifier used does not have a strong influence on the w(e) (or J(c)) value. The main difference between the three blends is the plastic work term (beta w(p)). Using the specific essential work of fracture approach, no plane stress-plane strain transition can be observed Fur impact rate of loading, the dynamic G(c), and the Izod impact strength for blends containing 10-30 wt% of IM were measured. All the blends failed in a brittle or semi-brittle manner. In general, G(c) increases with IM concentration. (C) 1998 Elsevier Science Ltd. All rights reserved.