The present work is a continuation of our efforts to design a cohesive zone model for modelling fracture of amorphous glassy polymers through the initiation, widening and breakdown of crazes. The challenge lies in devising a traction-separation law that not only mimics the growth of a craze (Estevez et al. 2000) at various loading rates and temperatures but also takes molecular level features into account. To this end, we are performing molecular dynamics simulations on unit cells consisting of a coarse-grained bead-spring model of polymer molecules. The models employed are similar to those used by Kremer and Grest (1990) for simulating effects of entanglements in polymer melts. Such models have also been used recently by Baljon and Robbins (2001) to study the phenomenon of crazing. Through the use of these models we expect to be able to generate traction-separation laws that are sensitive to the molecular weight and entanglement density of the polymer. These studies substantially improve upon the continuum models of growth and breakdown of craze fibrils that we have recently proposed (Mahajan et al. 2004).
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