Abstract: A homogeneous, thermoplastic mixture comprising (A) from 85 to 99.5% by weight of isotactic polypropylene; and (B) from 15 to 0.5% by weight of a liquid, saturated diorganopolysiloxane having a viscosity of from 30,000 to 80,000 cSt at 20.degree. C.The elastic properties of moulded articles produced from the polypropylene/diorganopolysiloxane mixtures of the present invention are substantially improved by the addition of small quantities of diorganopolysiloxane while their dimensional stability under heat and their rigidity are largely preserved.

Abstract: A process for the preparation of a stereospecific .alpha.-olefin polymerization catalyst which comprises (i) forming a solid carrier from an anhydrous magnesium compound and an electron donor compound; (ii) contacting the solid carrier obtained in step (i) with a solution of TiCl.sub.4 in an inert solvent; and (iii) reducing the TiCl.sub.4 with a reducing agent of the formulaAlR.sub.n X.sub.3-nwherein R is an alkyl group having from 1 to 18 carbon atoms, X is a halogen atom, and n is an integer such that 0<n.ltoreq.3.

Abstract: An elastomeric thermoplastic mixture comprising (A) from 40 to 95% by weight of polypropylene, and (B) from 5 to 60% by weight of a partially cross-linked ethylene/vinyl acetate copolymer which has a gel content of from 3 to 50% by weight and a vinyl acetate content of from 20 to 80% by weight, the percentages being based on the sum of A+B.

Abstract: A thermoplastic mixture comprising (A) from 2 to 40% by weight of a partially crystalline ethylene/propylene copolymer or terpolymer having an ethylene content of from 70 to 90% by weight and an endothermic heat of fusion of from 6 to 18 cal/g, (B) from 30 to 93% by weight of a crystalline polypropylene, and (C) from 5 to 30% by weight of a copolymer of ethylene and vinyl acetate containing from 20 to 70% by weight of vinyl acetate, the percentages being based on the sum of (A)+(B)+(C).