Localized plastic deformation in ternary polymer blends

Patterns of localized plastic strain in polycarbonate (PC)/acrylonitrile–butadiene–styrene (ABS) polymer blends are investigated numerically with respect to their dependence on the blend microstructure as well as their interrelation to toughening mechanisms in these materials. Modeling of the blends consists of two steps: the representation as a twophase material of ABS particles embedded in a PC matrix and the development of a homogenized constitutive description of ABS which itself has a heterogeneous microstructure. The constitutive models for the two phases account for large visco-plastic strains, the intrinsic softening-rehardening behavior of glassy polymers as well as plastic dilatation in the ABS phase to comprise the effect of rubber particle cavitation. Cell model calculations for periodic microstructures illustrate that patterns of localized plastic deformation in the blend are qualitatively different for different ABS modifier types. Network-like shear banding in the PC matrix is found to be beneficial for toughening by reducing peak hydrostatic stresses. Quantitative analyzes indicate that toughening in PC/ABS blends may be most efficient for a rubber content in ABS in an intermediate range of 5–35%.