Patent ID: 7517942

Claim:
A method for preparing reversibly cross-linked isotactic polypropylene having a degree of crystallinity substantially identical to a degree of crystallinity of a starting polypropylene comprising: A. mixing in the presence of heat; (1) a polymer selected from the group consisting of: (a) isotactic polypropylene homopolymer; (b) isotactic polypropylene copolymer; and (c) mixtures of isotactic polypropylene homopolymer and copolymer; (2) an elastomer; (3) an organic peroxide; and (4) an accelerator, forming macro-radicals; B. simultaneously coupling the macro-radicals with a sulfur obtaining an optimum cross-linking degree, wherein the accelerator is present in a concentration ranging from a 1:4 mass ratio with the sulfur to a 1:1 mass ratio with the sulfur, and wherein the weight fraction of the accelerator does not exceed the weight fraction of the organic peroxide.