Toughening of glassy polystyrene through ternary blending that combines low molecular weight polybutadiene diluents and ABS or HIPS-type composite particles

The effectiveness of toughening brittle glassy polymers such as polystyrene (PS) through deformation-induced plasticization by low molecular weight di luents of polybutadiene (PB) was amply demonstrated in earlier studies. In those applications, surface-initiated crazes of unusual growth kinetics and stability could produce effective toughening in sheet samples of millimete r thicknesses, but would have been ineffective in more massive parts where crazes could not be initiated in the interiors to promote a plastic respons e of the entire volume. This shortcoming has now been rectified through the development of ternary blends incorporating into the previous PS/PB blends a critical small volume fraction of ABS- or HIPS-type composite particles that serve to initiate crazes throughout the volume. Thus, we demonstrated in the present study that incorporation of 10% commerical ABS or 20% commer cial HIPS into the most effective PS/PB-3K blend results in tensile toughne sses equal to or exceeding those of commercial ABS or HIPS in full concentr ation. (C) 1999 John Wiley & Sons, Inc.