Toughening Polystyrene by Core-Shell Rubber Particles: Analysis of the Internal Structure and Properties

Abstract

A series of polybutadiene-graft-polystyrene (PB-g-PS) core-shell structural rubber particles has been prepared by grafting styrene onto polybutadiene seeds via emulsion polymerization. All the PB-g-PS particles were designed with the same chemical composition and similar grafting degree but different internal structures. The difference in internal structure was realized by controlling the allocation of ‘external grafting’ and ‘internal grafting’ of styrene. Three different internal structures: rare sub-inclusion, small size sub-inclusions and large-scale sub-inclusions in the rubber phase were observed by transmission electron microscopy. Slight aggregation of rubber particles of PB-g-PS with large-scale sub-inclusions was found in PS/ PB-g-PS blends. The results of dynamic mechanical analysis showed the PB-g-PS with small size sub-inclusions had lower glass transition temperature than the others. Izod test results showed that the PB-g-PS with large-scale sub-inclusions could toughen the PS matrix more effectively. The deformation mechanisms responsible for these effects are discussed.