Electrical properties of structured HIPS/gamma-irradiated UHMWPE/carbon black blends

HIPS/UHMWPE and HIPS/XL-UHMWPE containing carbon black (CB) are unique systems in which CB is attracted to the PE, and thus structuring takes place affecting the morphology and the resultant electrical properties. UHMWPE, having a very high viscosity, was chosen as the dispersed phase within HIPS in place of a conventional polymer in order to explore possibilities of obtaining unique structures that would induce the CB to segregate and form a conductive network. XL-UHMWPE particles also constitute an interesting dispersed phase, maintaining their highly porous and intricate structure even subsequent to melt processing. In both cases the CB is located at the interface; however, differences in resistivity values are observed. When low UHMWPE or XL-UHMWPE contents are incorporated, the HIPS/XL-UHMWPE/CB compositions have lower resistivities due to the heterogeneity of the interface, even at high shear rates. When high UHMWPE or XL-UHMWPE contents are utilized, the trends reverse: HIPS/UHMWPE/CB depict enhanced conductivity, due to the dominance of UHMWPE particle coalescence and the resultant decrease in surface area. This is contrary to what happens with the XL-UHMWPE particles, where the surface area increases with their higher contents, since they do not coalesce.