Abstract: Propylene polymer obtained by melt-blending of:100 parts by weight of polypropylene;from 0.01 to 10 parts by weight of a functional compound (a) comprising at least 2 acrylate groups;at least 0.005 part by weight of a sulphur-containing compound (b) chosen from thiuram sulphides; andfrom 0.01 to 5 parts by weight of a compound (c) capable of generating free radicals.

Abstract: Catalyst systems comprising, on the one hand, a catalytic solid based on complexed titanium trichloride and, on the other hand, a nonhalogenated organoaluminium activator. When employed in gas phase olefin polymerization processes, these catalyst systems make it possible to manufacture a wide range of homopolymers and copolymers (random and block) with an isotacticity index which can be adjusted to very low values and with excellent pourability, even in the case of copolymers of high comonomer content. In the absence of transfer agents they also make it possible to synthesize polymers of very high molecular masses, with an increased activity. These polymerization processes yield particularly advantageous results in the case of propylene.