A New Mechanism of Toughening Glassy Polymers. 2. Theoretical Approach

A theoretical model is presented for the toughening of brittle glassy polymers by the controlled solvent crazing action of precipitated low molecular weight rubber diluents existing in the form of randomly dispersed small spherical pools. In this mechanism the central process is the increased sorption of the diluent under the deformation-induced negative pressure existing in a boundary layer on the craze periphery where the sorbed diluent produces substantial plasticization that significantly lowers the craze flow stress to prevent premature craze fracture. The resulting expressions for the reduction of the craze flow stress with increasing volume fraction of diluent are in excellent agreement with experimental measurements. © 1990, American Chemical Society. All rights reserved.