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

HIPS/UHMWPE and HIPS/XL-UHMWPE containing carbon black (CB) are unique syst ems in which CB is attracted to the PE, and thus structuring takes place af fecting the morphology and the resultant electrical properties. UHMWPE, hav ing a very high viscosity, was chosen as the dispersed phase within HIPS in place of a conventional polymer in order to explore possibilities of obtai ning unique structures that would induce the CB to segregate and form a con ductive network. XL-UHMWPE particles also constitute an interesting dispers ed phase, maintaining their highly porous and intricate structure even subs equent 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 do minance of UHMWPE particle coalescence and the resultant decrease in surfac e area. This is contrary to what happens with the XL-UHMWPE particles, wher e the surface area increases with their higher contents, since they do not coalesce.