Effect of melt flow on morphology and linear thermal expansion of injection-molded ethylene-propylene-diene terpolymer/isotactic polypropylene blends

Abstract

An ethylene–propylene–diene terpolymer/isotactic polypropylene blend with a structure of co-continuous microlayers was fabricated by injection molding and was then investigated. The blend exhibited an extremely low coefficient of linear thermal expansion (CLTE) in the directions of the length and the width. As the thickness of the oriented portion increased, the CLTE was further reduced. The morphology of the co-continuous microlayers and the thermal expansion behavior varied with the sampling positions on the injection-molded sheets. To study the relationship between the morphology and the melt flow, the melt flow behavior during injection molding was simulated using Moldflow. Orientation of the microlayers was determined using shear flow. When the shear rate increased, the orientation state increased and the CLTE decreased. © 2015 Society of Chemical Industry