Macroscopic yield in cavitated polymer blends

Polymer blends in which the rubber particles have cavitated may be regarded as porous materials. The yield behaviour of many porous media can be well described with the Gurson model. Polymers, however, are characterized by la rge elastic strains prior to yield. These effects are neglected in the orig inal Gurson formulation, which, as will be shown, leads to an overestimatio n of the yield stress for the voided blend. The localization of polymer pla sticity in narrow shear bands also results in deviations from the standard theory. This paper presents two-dimensional cell calculations of a voided p olymer and demonstrates that the overall yield characteristics are not repr esented well by the Gurson potential. A modification of this potential is p roposed that accounts for elasticity effects and shear banding and gives be tter agreement with the cell results. The new potential is generalized to a full three-dimensional continuum model for voided polymer blends. (C) 2001 Elsevier Science Ltd. All rights reserved.