A New Mechanism of Toughening Glassy Polymers. 1. Experimental Procedures

Normally brittle, high molecular weight polystyrene can be very effectively toughened by blending polybutadiene of 2.76 kg/mol at volume concentrations of a few percent. An increase of toughness by about a factor of 10 above that of homo-PS can be readily achieved with a 1.1% PB-2.76K blend if the precipitated PB pools can be maintained at a size smaller than 0.2 μm. It is proposed that this dramatic effect is the result of a controlled solvent crazing action of the PB-2.76K on the homo-PS when the former becomes soluble into the latter in the fringing layers of the craze borders subjected to negative pressure by the local craze tuft drawing process. © 1990, American Chemical Society. All rights reserved.