Micromechanics of particle-modified semi-crystalline materials

ness The impact strength of several semi-crystalline polymers can be improved by the dispersion of second-phase rubber particles. A criterion for the effect of this practice is based on the average interparticle matrix ligament thickness. The critical interparticle distance is considered to be an intrinsic material property of the matrix. A toughening mechanism has recently been suggested which considers a layer of transcrystallized material around well dispersed particles, having a reduced yield strength in certain preferentially oriented directions. In this work, the potential of local anisotropy for the toughening of semi-crystalline polymeric material is investigated. The matrix material is modeled within the framework of anisotropic Hill plasticity with a rate dependent and hardening yield stress. Different micromechanical models are used to study the effect of anisotropy on both the deformation and the hydrostatic stress fields in particle-modified systems. A reduced plastic shear resistance of percolating transcrystallized material is found to be very effective in inducing extensive delocalized shear deformations and alters the location of the peak tensile hydrostatic stresses. J.A.W. van Dommelen, W.A.M. Brekelmans and F.P.T. Baaijens