Encapsulated phase structure and morphology evolution during quiescent annealing in ternary polymer blends with PA6 as matrix

Abstract

This work is aim to study the encapsulated morphology development in ternary blends of polyamide 6/high density polyethylene/maleic anhydride-grafted-ethylene propylene diene monomer (PA6/HDPE/EPDM-g-MA) and polyamide 6/maleic anhydride-grafted-high density polyethylene/ethylene propylene diene monomer (PA6/HDPE-g-MA/EPDM) through thermodynamically control described by Harkins spreading theory. The phase morphology was confirmed by using scanning electron microscope (SEM) and selective solvent extraction revealed that PA6/HDPE/EPDM-g-MA blend having a composition of 70/15/15 vol % is constituted of polyamide 6 matrix with dispersed composite droplets of HDPE subinclusions encapsulated by EPDM-g-MA phase, while for PA6/HDPE-g-MA/EPDM blend with the same composition is constituted of polyamide 6 matrix with dispersed composite droplets of HDPE-g-MA subinclusions encapsulated by EPDM phase. Quiescent annealing test revealed that for PA6/HDPE/EPDM-g-MA blend, a perfect core-shell structure with one HDPE particle encapsulated by EPDM-g-MA phase was formed during annealing, and for PA6/HDPE-g-MA/EPDM blend, a novel complete inverting HDPE-g-MA/EPDM core/shell structure was achieved. Moreover, quantitative analysis about coalescent behaviors of HDPE-g-MA and HDPE subinclusions during quiescent annealing were investigated by image analysis and the result suggested that the grafted maleic anhydride group in HDPE-g-MA, acted as a role of steric repulsion, could suppress coalescence effects, thus leaded to a lower coalescent rate than that of HDPE subinclusions. © 2013 Wiley Periodicals, Inc.