Process for producing creep resistant cross-linked products from polypropylene and polybutene-1, and the cross-linked products so produced

Claim 1

A PROCESS FOR INCREASING THE CREEP RESISTANCE OF LINEAR CRYSTALLINE HOMOPOLYMERS MADE UP OF ISOTACTIC MACROMOLECULES AND SELECTED FROM THE GROUP CONSISTING OF POLYPROPYLENE AND POLYBUTENE-1, WHICH PROCESS CONSISTS ESSENTIALLY OF THE STEPS OF MIXING THE LINEAR HOMOPOLYMER WITH FROM 1% TO 10% BY WEIGHT OF DICUMYL PEROXIDE AND WITH FROM 5% TO 50% BY WEIGHT OF A MONOMERIC MATERIAL SELECTED FROM THE GROUP CONSISTING OF STYRENE AND DIVINYL BENZENE, AND HEATING THE MIXTURE AT A TEMPERATURE OF ABOUT 170*C., TO PRODUCE A POLYPROPYLENE AND POLYBUTENE-1 RESPECTIVELY, HAVING CROSS-LINKS MADE UP OF UNITS DERIVED FROM THE MONOMERIC MATERIAL BETWEEN THE CHAINS THEREOF, THE CROSS-LINKED HOMOPOLYMER BEING RESISTANT TO SOLVENTS AND TO CREEPING AT TEMPERATURES ABOVE THE MELTING POINT OF THE CRYSTALLINE ISOLATIC HOMOPOLYMER, AND BEING FURTHER CHARACTERIZED IN THAT IT HAS SUBSTANTIALLY THE SAME DENSITY, MECHANICAL PROPERTIES, HARDNESS, FLEXIBILITY, BRITTLE POINT, POWER FACTOR, VOLUME RESISTIVITY, AND DIELECTRIC CONSTANT AS THE STARTING LINEAR HOMOPOLYMER AT THE TEMPERATURES OF NORMAL USE, AND A STRESS-ELONGATION CURVE WHICH IS SIMILAR TO THAT OF VULCANIZED RUBBER.