CROSSLINKED, HEAT SHRINKABLE POLYPROPYLENE COMPOSITIONS

A heat-shrinkable article suitable for use as an insulating or coating material comprises a crosslinked composition of a polypropylene homopolymer or copolymer and an ethylene- propylene elastomer. The article is formed by a process comprising: i) creating a blend of the polypropylene homopolymer or copolymer and the ethylene-propylene elastomer by melt mixing; ii) melt processing the blend produced in i) to produce a melt processed material; iii) crosslinking the melt processed material produced in ii) by exposing it to radiation to produce a crosslinked material; iv) stretching the crosslinked material at a first temperature close to or above its softening or melting point and subsequently cooling it to a second temperature below its softening or melting point, to thereby freeze the crosslinked material i n its stretched form. Subsequent heating of the article close to or above its softening point or crystalline melting point results in recovery of the pre-stretched dimensions of the article. Due to i ts relatively high content of polypropylene, the heat-shrinkable article thus produced has greater toughness and rigidity than polyethylene-based systems, making it suitable for use as insulation for wires and cables a heat-shrinkable corrosion resistant sleeves for high-temperature transmissionpipeline joints, and for heat-shrinkable tubing or shapes for electrical insulation a nd mechanical protection.