Crazing is an important failure mechanism in glassy amorphous polymers. Crazing involves intense localized plasticity prior to failure and hence, controlling craze nucleation, growth and breakdown are potential strategies for increasing the fracture toughness of these materials. Several aspects of the mechanics of a craze like craze initiation, craze morphology and the role of entanglements are still not well understood. In the present work, we attempt to investigate these aspects through carefully designedMolecular Dynamics (MD) simulations on sufficiently large macromolecular ensembles. A methodology to estimate and characterise the entanglement structure was developed. Local regions of low entanglement density were found to serve as ideal nucleating sites. Craze growth occurs through few ingenuous mechanisms of entanglement rearrangement. We also establish that only the very large clusters of binary contacts act as indestructible entanglements. These micro scale phenomena provide a comprehensive understanding of the macro scale phenomena like yielding, strain softening and hardening.

Keywords: Crazing, Polymers, Entanglements, Initiation, Growth.