Silicone based process aids are well know in the art. For example, U.S. Pat. Nos.: 5,708,084 and 5,708,085 teach polyolefin compositions which can be extruded at relatively high rates to provide extrudate having increased hydrophobicity, said compositions comprising (A) 100 parts by weight of a thermoplastic resin; (B) 1 to 5 parts by weight of an interactive diorganopolysiloxane process aid, said diorganopolysiloxane having a number average molecular weight of at least 10,000.