The effects of nanotube fillers on craze formation in simulated glassy polymers under tensile load

We consider the work required to deform uniformly dense polymer systems of glassy bead-spring chains filled with rod-like inclusions with aspect ratio akin to carbon nanotubes (CNTs). We consider 0, 0.40, and 2.0 wt% of filler particles. For each composition, we vary the attractive strength of the polymer–inclusion interaction between one and eight times the nominal polymer–polymer interaction strength. Significant enhancements in plateau stress and work of deformation are observed only for the highest weight fraction of the most attractive inclusions. We show that the primitive path algorithm can be used in polymer glasses to simplify the identification of entanglements. We show that the number of entanglements and chains bridging multiple inclusions cannot be directly used to predict the toughness of the polymer composite. Our results indicate that entanglements do not appear to be the primary molecular-scale structural features responsible for determining material properties of polymer glasses.