Effect of Na-ionomer on dynamic rheological, dynamic mechanical and creep properties of acrylonitrile styrene acrylate (ASA)/Na+1 poly (ethylene-co-methacrylic acid) ionomer blend

A special class of engineered copolymers, called ionomers, comprising both electrically neutral repeating units and a fraction of ionized units was melt blended to weather resistant acrylonitrile/styrene/acrylate (ASA) terpolymer for improved electrical conductivity, heat sealing ability, direct adhesion to several polymers, glass and metals without affecting the aesthetics and colorability of ASA. The similar chemical nature of one of the components of each blended materials viz. acrylate rubber in ASA and acrylic acid of Na-ionomer in addition to the presence of ionic crosslinking within Na-ionomer, polar acrylonitrile group in ASA affects chain dynamics as compared to neat polymers. In this context, dynamic rheological properties, DMA properties, creep behavior and DSC of the newly developed ASA/Na-ionomer blends were analyzed. Based on Na-ionomer content, the blend system either forms "mushroom" or "brush" type conformation and formation of ionic crosslinking in "brush regime" leads to three tiers Caylay tree conformation. The different chain topology resulted into characteristic loss modulous (G") curve during stress relaxation process. The chain conformation as well as ionic crosslinking and ion-dipole interaction between the blend components also affected DSC endotherm peak and glass transition temperature. The tan delta peak temperature from DMA also revealed the similar observation. The creep compliance of the blends was dependent on Na-ionomer content and with temperature. The Findley model analysis of creep compliance suggested that the creep compliance was depended on Na-ionomer content and ionic crosslinking controlled the creep. The findings can be utilized to design weather resistant smart polymer using suitable filler system. Copyright 2014 John Wiley & Sons, Ltd.