Effect of blended ionomers on the strain hardening of polyester-type elastomer/ionomer blends

Abstract

A Na-type ionomer based on poly(ethylene-co-methacrylic acid) (EMAA-Na ionomer) was blended with thermoplastic polyester elastomer (TPEE) and the effect on uniaxial elongational viscosity was investigated. To clarify the effect of the degree of neutralization (ND) by the EMAA-Na ionomer on strain hardening of TPEE/ionomer blends system, EMAA-Na ionomers with different NDs were prepared and blended with TPEE above their melting temperature using a twin screw extruder. An unexpected strong strain hardening was observed for a ND above 40% for a TPEE/EMAA-Na blend ratio of 80/20 wt %, which corresponds to the critical ND for the formation of ion aggregates. The results can be explained using the acid-cation exchange mechanism proposed by Vanhoorne and Register. It is considered that blending EMAA-Na ionomers is an effective method for the modification of TPEE with respect to the intensity of strain hardening under uniaxial elongation. ©2009 The Society of Polymer Science, Japan.