a composition comprising : a crosslinkable thermoplastic resin ; an aliphatic monomeric compound having two or more carbon to carbon double bonds ; an organic peroxide crosslinking agent ; and a linear organopolysiloxane / alpha - olefin copolymer having the following formula : ## str1 ## wherein r is a saturated aliphatic or aromatic group and each r is alike or different ; a is about 1 to about 1000 ; and b is about 5 to about 100 the composition is useful as coating composition for an electrical conductor .