Effect of PBT melt viscosity on the morphology and mechanical properties of compatibilized and uncompatibilized blends with ABS

Abstract

The toughness and morphology of poly(butylene terephthalate), PBT, blends with acrylonitrile–butadiene–styrene, ABS, materials are very sensitive to the PBT molecular weight or melt viscosity. High PBT melt viscosity is shown to lead to improved ABS (and styrene–acrylonitrile copolymer, SAN) dispersion which improves the low temperature fracture toughness of PBT/ABS blends. Compatibilization by methyl methacrylate, glycidyl methacrylate, ethyl acrylate terpolymers, or MGE, was shown to further improve ABS and SAN dispersion and reduce the ductile–brittle transition temperature. Addition of the compatibilizer broadens the window of acceptable processing temperatures. The minimum quantity of ABS required to toughen PBT is lower the higher the PBT melt viscosity. The tensile properties of PBT/ABS/MGE blends were shown to be relatively insensitive to PBT melt viscosity or reactive compatibilization.