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) blends was investigated. A significant reduction of dispersed phase dimension was observed when chlorinated polyethylene (CPE) was added to EPDM/PA blend, due to interaction that exists between CPE and PA. Based on differential thermal analysis, dynamic mechanical thermal analysis, scanning electron microscopy and transmission electron microscopy characterization, a speculative description of configuration was proposed to interpret the morphological investigation made on these blends. Cold milling of molten EPDM/PA/CPE blend gives rise to in situ fibril rubber compound, which can be mixed with curatives and statically vulcanized to give reinforced rubber compositions. Compared with vulcanized conventional rubber short fiber composites, the compositions show notably different elongation properties. The reason was given. It was shown that mechanical property of EPDM/PA/CPE blend could be improved by adding only a small amount of PA fibrils (i.e. 10%), which is different to that of conventional rubber short fiber composite. Based on above analysis, three forms of structures were proposed to discuss the relationship between the morphologies and mechanical properties. The studies of mechanical properties show that the materials obtained possess useful strength and excellent heat resistance.