HIPS/gamma-irradiated UHMWPE/carbon black blends: Structuring and enhancement of mechanical properties

CB-containing HIPS/UHMWPE and HIPS/XL-UHMWPE are unique systems, in which s tructuring takes place, affecting the electrical (to be described in a futu re article), rheological, mechanical, and dynamical-mechanical properties. The XL-UHMWPE particles have undergone structural fixation due to the cross linking, maintaining their porosity and internal intricate structure even a fter high-temperature melt processing, as opposed to the UHMWPE particles. Differences in the flow mechanisms of HIPS/UHMWPE and HIPS/XL-UHMWPE blends have been attributed to polymer viscous flow in the former case vs. partic le slippage in the latter. The mechanical properties of HIPS/UHMWPE are enh anced when utilizing XL-UHMWPE as a dispersed phase, especially the strengt h, because of changes in the inherent properties of the UHMWPE following ir radiation, and in particular, the nature of the HIPS/XL-UHMWPE interface. T he results for the CB-containing 70HIPS/30XL-UHMWPE blend are especially su rprising and of practical importance, due to the fact that no degradation o f the mechanical properties has occurred as a result of the CB incorporatio n. The dynamical mechanical properties reflect the differences between the UHMWPE and XL-UHMWPE-containing blends as well. The presence of either type of UHMWPE, CB content, and blend composition affect the dissipation, but h ave only a minor influence on the transition temperatures of the components . Of special interest is the increased damping of XL-UHMWPE-containing comp ositions. (C) 1999 John Wiley & Sons, Inc.