Abstract: A semi-conductive or insulating composition includes an ethylene/octene copolymer and at least one additional polymer, such as ethylene/vinyl acetate. The composition may also include carbon black and other additives. The composition may be used as a semi-conductive or insulating layer in such applications as electrical cables.

Abstract: Vulcanizable semiconductive shield compositions contain a linear, single-site catalyzed polymer formed by polymerizing ethylene with at least one comonomer selected from C.sub.3 to C.sub.20 alpha-olefins; a carbon black selected from furnace carbon blacks that contain ash and sulfur in amounts of 50 ppm or less and have crystal dimensions L.sub.a and L.sub.c of 30 .ANG. or less, acetylene carbon blacks, and furnace carbon blacks having an ASTM grade of N-351; and a crosslinking agent. The compositions may be used to manufacture semiconductive shields for electrical conductors, such as power cables. The semiconductive shields exhibit improved processability, low water vapor transmission and low shrinkback, without abrading or corroding extrusion equipment.