A MODEL FOR IZOD STRENGTH IN IMPACT-MODIFIED POLYSTYRENE

The strength of impact-modified polystyrene is related to the volume o f craze matter generated in fracture. In the Izod test, crazes tend to initiate and propagate between interacting neighbours. The efficiency of craze termination is also critical to toughness, and depends upon the particle morphology. Using computer simulations of crazes propagat ing through an array of model particles, it has been possible to quant itatively model the crazing process and predict strength. The model is applicable to materials having a wide range of particle sizes, rubber phase volumes, and either solid or occluded particles. Predictions ar e in good agreement with data obtained for experimental blends as well as commercial HIPS.