Abstract: Shaped articles of cross-linked polymers comprising a first component having little or no cross-linking and high elongation, and a second component having a relatively high level of cross-linking and low elongation. Such articles are particularly useful in the form of electrical insulation, the first component being adjacent to a wire or other conductor. Preferably each of the components comprises a crystalline fluorocarbon polymer, especially an ethylene/tetrafluoroethylene copolymer. Such articles can be prepared by (1) melt-extruding a first polymeric composition which contains little or no cross-linking agent, and a second polymeric composition which contains a greater amount of cross-linking agent, (2) maintaining the two extrudates under conditions such that cross-linking agent migrates from the second to the first composition, and (3) cross-linking both compositions, preferably by radiation.