Effects of physical crosslinking on properties of plasticized high molecular weight PVC

Abstract

A series of high molecular weight PVC (HMW-PVC) resin was synthesized by suspenion process at various temperatures and compounded to prepare plasticized HMW-PVC. Plasticized HMW-PVC is physically crosslinked by microcrystallites and chain entanglements. The molecular weight and degree of crystallinity of PVC resin increase with decrease of polymeri-zation temperature. More dense physical crosslinking networks are formed in plasticized PVC with the decrease of polymerization temperature of PVC resin. Plasticized HMW-PVC exhibits thermal reversible processability, but the gelation temperature and melt viscosity increase with increasing physical crosslinking density. Physical crosslinking also has great effects on the mechanical properties of plasticized HMW-PVC. The compression set and deformation decrease as molecular weight and crystallinity of PVC resin increase, but the softening temperature and tensile strength increase. The crosslinking network of plasticized HMW-PVC is more similar to the dissociable network of gels than to the permanent network of crosslinked rubber and is not stable under stretching at high stress.