Effects of compatibilizing agent and in situ fibril on the morphology, interface and mechanical properties of EPDM/nylon copolymer blends

The effect of several compatibilizers on mechanical property and morphology of ethylene-propylene diene monomer rubber (EPDM)/ nylon copolymer (PA) bl ends was investigated. A significant reduction of dispersed phase dimension was observed when chlorinated polyethylene (CPE) was added to EPDM/PA blen d, due to interaction that exists between CPE and PA. Based on differential thermal analysis, dynamic mechanical thermal analysis, scanning electron m icroscopy and transmission electron microscopy characterization, a speculat ive description of configuration was proposed to interpret the morphologica l investigation made on these blends. Cold milling of molten EPDM/PA/CPE bl end gives rise to in situ fibril rubber compound, which can be mixed with c uratives and statically vulcanized to give reinforced rubber compositions. Compared with vulcanized conventional rubber short fiber composites, the co mpositions show notably different elongation properties. The reason was giv en. It was shown that mechanical property of EPDM/PA/CPE blend could be imp roved by adding only a small amount of PA fibrils (i.e. 10%), which is diff erent to that of conventional rubber short fiber composite. Based on above analysis, three forms of structures were proposed to discuss the relationsh ip between the morphologies and mechanical properties. The studies of mecha nical properties show that the materials obtained possess useful strength a nd excellent heat resistance. (C) 2001 Published by Elsevier Science Ltd.