COMPATIBILIZING EFFECT OF A MALEIC-ANHYDRIDE FUNCTIONALIZED SEBS TRIBLOCK ELASTOMER THROUGH A REACTION INDUCED PHASE-FORMATION IN THE BLENDS OF POLYAMIDE-6 AND POLYCARBONATE .1. MORPHOLOGY AND INTERFACIAL SITUATION

The result of a study on the effect of polylstyrene-b-(ethylene-co-but ylene)-b-styrene] triblock copolymer functionalized by maleic anhydrid e (SEBS-gMA) on the morphology and interface of the incompatible polym er blends of polyamide 6 (PA6) and polycarbonate (PC) is presented. Th e electron spectroscopic imaging with transmission electron microscopy was introduced to investigate the morphological features and interfac ial situation of these blends. It has been found that the functionaliz ed SEBS is dispersed in PA6 phase at about 50 nm in diameter and also exists on the domain boundary of PA6 and PC to envelope the PC domains in the blends with a matrix of PA6, while the unmodified SEBS attache s to PC particles but does not surround the domains. This means that t he in situ reaction between PA6 and SEBS-gMA during mixing induces the envelop formation of SEBS on PC domains. The formation of SEBS-gMA ph ase on the interface works as a coupling agent to improve interfacial adhesion between PA6 and PC, which leads to the disappearance of voids on the domain boundary generated due to the different volume shrinkag e between PA6 and PC in fast cooling in a mould. In the PC rich blends , SEBS-gMA is occluded in PA6 domains and exists on the interface betw een PA6 and PC, while with unmodified SEBS the dispersed SEBS and PA6 phases form separate dispersed phase in PC matrix. Dynamic mechanical analysis has revealed that the glass transition temperatures (T(g)s) o f PA6 and PC phases in the blends are slightly lower than the respecti ve pure polymers and that the incorporation of SEBS-gMA does not affec t the T(g)s of each phase. This indicates that chemical reactions betw een PA6 and PC during melt mixing, which produce low molecular weight species of PC occurred regardless of the incorporation of SEBS-gMA and that SEBS-gMA on the domain boundary is not miscible enough to reside within the PC domains. Copyright (C) 1996 Elsevier Science Ltd.