Influence of filler-polymer interactions on the cure mismatch of dissimilar polymeric blends

Abstract

Cure mismatch between the blends of two dissimilar polymers, poly[ethylene(vinyl acetate)](EVAc-28, VAc content 28%) and polychloroprene (CR) was investigated through rheometric, mechanical, and dynamic mechanical properties. These studies indicate cure-heterogeneity due to fast curing as well as degradation of CR with dicumyl peroxide (DCP) at 170°C, which facilitates easy liberation of acidic HCl. The low temperature curing of unfilled blends at 145°C reduces the rate of curing as well as liberation of HCl, leading to lower cure heterogeneity and improved physical properties compared to those cured at 17°C. The high specific component of surface energy of carbon black (N110) leads to better filler-polymer interaction with more polar CR and causes lowering in effective occluded volume measured from storage modulus. Carbon black suppresses the cure heterogeneity of the blends and improves their physical properties considerably. CR, which shows higher minimum rheometric torque compared to EVAc-28, is more viscous and hence carbon black incorporation is relatively difficult. This also leads to higher agglomerate structure causing higher networking factor. © 1997 John Wiley & Sons, Inc.