EFFECT OF VISCOSITY RATIO AND PEROXIDE COAGENT TREATMENT IN PP/EPR/PETERNARY BLENDS/

Ternary blends of PP/EPR/PE (isotactic polypropylene/ethylene-propylen e rubber/high density polyethylene) (80/10/10 by weight) were prepared using a corotating twin screw extruder. The effect of the viscosity r atio of a rubber domain (EPR + PE) to a matrix PP (eta(EPR)/eta(PP)), and peroxide/coagent treatment on the micrograph (POM), rheology, and mechanical properties of the blend have been studied. Rubber domain si ze was easily controlled by the addition of PE. When PE satisfying eta (PE) < eta(EPR) was added, the rubber domain size decreased, and vice versa. With increasing viscosity ratio, the rubber domain size increas ed and the crystallization temperature (T-cc) of PP and impact strengt hs of the blend decreased. The effects of peroxide treatment on domain size seem dual, i.e. originally small domains become larger and vice versa. By contrast, the addition of coagent reduced the domain size an d improved the interfacial adhesions. The spherulite size increased so mewhat with peroxide treatment, and significantly decreased with coage nt treatment. Copyright (C) 1996 Elsevier Science Ltd