Abstract: There are disclosed new solid catalyst-forming components for use in preparing catalysts for the stereoregular polymerization of alpha-olefins containing at least 3 carbon atoms, mixtures of alpha-olefins with one another and/or with ethylene, said components being obtained by reacting(a) at least one hydrocarbon-soluble halogenated Ti compound;(b) a product comprising a Mg dihalide obtained by decomposition of an adduct of at least a Mg dihalide and an electron-donor compound present in the adduct in an amount of at least 0.5 mole per mole of Mg dihalide, the decomposition product being characterized in that, in its X-rays powder spectrum, instead of the diffraction line of maximum intensity which appears in the X-rays powder spectrum of the normal Mg dihalide, a halo appears whose intensity maximum is shifted with respect to said line, and(c) an electron-donor compound which does not contain active hydrogen atoms.

Abstract: New catalysts for the polymerization and copolymerization of olefins are disclosed. The catalysts are prepared from (1) a new class of metal complexes of general formula M.sub.m M'X.sub.2m Y.nE, in which M is Mg, Mn and/or Ca; m is a number from 0.5 to 2.0; M' is Ti, V and/or Zr; X is Cl, Br or I; Y is one or more atoms or groups of atoms of various kinds in an amount such as to satisfy the valence of M'; n is a number from 0.5m to 20m; and E is an electron-donor compound; and (2) organometallic compounds of metals belonging to one of Groups I to III of the Mendelyeev Periodic Table.

Abstract: There are disclosed new starting components for use in preparing catalysts for the polymerization and copolymerization of olefins. The new starting components are compounds having the general formulae R.sub.2 AlOR" and/or RAl (OR").sub.

Abstract: High yields of elastomeric copolymers of ethylene and higher alpha-olefins, or of ethylene, higher alpha-olefins and unsaturated monomers (polyenes) containing two or more double bonds are obtained by copolymerizing a mixture of the monomers in contact with a catalyst prepared by mixing a catalyst-forming component which is an organometallic compound of aluminum with a supported catalyst-forming component obtained by contacting a halogenated titanium compound with a carrier or support consisting of or comprising an anhydrous Mg or Mn halide partially or completely complexed with a Lewis base capable of forming a complex with it.The copolymers so obtained have valuable mechanical properties, in particular a relatively low value of permanent set and do not exhibit excessive residual deformation at break.