A polymeric material mixture comprising a fluorine-containing polymer, a siloxane polymer, and at least two polymer processing additives (PPA), wherein the at least two polymer processing additives have different chemistries. For example, there can be a flexible coextruded pipe for providing a protective housing for cables, fluids, sludge or solids, the pipe comprising a pair of telescopically related inner and outer layers, where said inner layer is lubricated with the polymeric material mixture.