Abstract: Multilayer material, essentially without adhesives between the various layers, particularly with two or three layers, consisting of at least one layer of aliphatic polyamide and at least one layer, alternating with the polyamidic layer, of vulcanized acrylic rubber, the above materials being characterized by a peeling strength (between the polyamidic layer and the vulcanized acrylic rubber layer) of more than 5 daN/cm.The process for the preparation of the above material is also described.

Abstract: The preparation and use of organometallic complexes of Group III metals having the formula:Me(Ar)(AlX.sub.3 R).sub.3 (I)wherein Me, Ar, X and R are as defined herein, to stereospecifically polymerize unsaturated monomers is provided.

Abstract: A catalytic system to polymerize diolefinic monomers consists of a lanthanide salt, an organometallic compound of a metal belonging to groups I, II and III of the periodic table of elements and an organometallic compound of boron. The polymers obtained are characterized in that they have a high degree of 1,4 chain units and ratio between 1.4-cis/1,4-trans units which can vary as desired, and also a narrow molecular weight distribution.

Abstract: Organometallic complexes of lanthanides with a well-defined stoichiometry which can be used in the stereospecific polymerization of unsaturated monomers, can be represented by the general formula:Me(Ar)(AlX.sub.3 R).sub.3 (1)wherein: Me represents a metal with atomic number 21, 39, or an atomic number of between 57 and 71, Ar represents benzene or a susbstituted benzene with from 1 to 3 alkyl groups containing from 1 to 10 carbon atoms, X is a halogen atom, whereas R is a linear, cyclic or branched alkyl radical containing from 1 to 12 carbon atoms;the preparation of the complexes is described together with their use in the stereospecific copolymerization of unsaturated monomers.

Abstract: A catalytic system to polymerize diolefinic monomers consists of a lanthanide salt, an organometallic compound of a metal belonging to groups I, II and III of the periodic table of elements and an organometallic compound of boron. The polymers obtained are characterized in that they have a high degree of 1,4 chain units and ratio between 1.4-cis/1,4-trans units which can vary as desired, and also a narrow molecular weight distribution.

Abstract: New organometallic derivatives of group IIIA are described having general formula M(C.sub.6 F.sub.5).sub.3 wherein M is a metal of group IIIA selected from aluminium, gallium and indium.The above derivatives are prepared by exchange reaction between a metal alkyl MR.sub.3 with an organometallic derivative of boron having the formula B(C.sub.6 F.sub.5).sub.3.

Abstract: Organometallic complexes of lanthanides with a well-defined stoichiometry which can be used in the stereospecific polymerization of unsaturated monomers, can be represented by the general formula:Me(OR).sub.3 *(Me.sub.1 R.sup.1 R.sup.2 R.sup.3).sub.xwherein, Me represents a metal with atomic number 21, 39, or an atomic number between 57 and 71, OR is an alkoxylic group of an alcohol; Me represents a metal of the group IIIA, whereas R.sup.1, R.sup.2, R.sup.3 can be H, or a linear, branched or cyclo-aliphatic alkyl radical containing from 1 to 10 carbon atoms and x is an integer (3 or 4) and depends on the type of alkoxide used.The preparation of the complexes is described and their use in the stereospecific polymerization of unsaturated monomers.

Abstract: The processability of a polybutadiene with a high content of 1,4-cis-structure is improved by means of the addition of PCl.sub.3 before the polymerization reaction is quenched and when Mooney viscosity of polybutadiene has reached a prefixed value, preferably lower than, or equal to 30; the polymerization of butadiene is carried out in a solution in an aliphatic or cycloaliphatic solvent, in the presence of a catalytic system based on rare earths, preferably a neodymium-based catalytic system.