Fracture toughening behavior of elastomer modified polyphenylene ether/polyamide blends

A series of blends of poly(2,6-dimethyl-p-phenylene)ether (PPE)-polyamide 6 (PA6) toughened with ethylene-propylene-diene terpolymer (EPDM) were prepared by injection molding. The fracture toughness of these blends was determined according to ASTM E813-89 method. Scanning electron microscopy (SEM) was used to observe the fracture morphology of these blends after three point bend loading. The J integral analysis revealed that the PPE homopolymer exhibited the lowest fracture toughness. SEM examination showed that the fracture surface of the slow crack growth zone is relatively smooth. On the other hand, the 30 wt% PPE-70 wt% PA6/EPDM(85/15) blend exhibited the highest critical fracture toughness (J_c) and tearing modulus (T_m) values. This was due to the formation of fibrillated structure in the slow crack growth zone. Generally, the morphology of the fracture surfaces of the blends after three point bend test was consistent with the change in J_c and T_m values. © 1998 Elsevier Science Ltd. All rights reserved.