Abstract: Multistage process for the polymerization of one or more olefins of the formula CH.sub.2 .dbd.CHR, in which R is hydrogen or an alkyl, cycloalkyl or aryl group having from 1 to 10 carbon atoms, comprising:(A) a first stage of polymerization, in which a first olefin polymer is prepared in the presence of titanium catalyst or vanadium catalyst;(B) a treatment stage in which the catalyst used previously is deactivated and in which a metallocene compound is supported on the olefin polymer produced in stage (A); and(C) a second stage of polymerization in which one or more olefins are polymerized in the presence of the product obtained from stage (B).

Abstract: Shaped articles for biomedical use characterized by a good transparency and flexibility also at low temperatures are prepared starting from elastomeric copolymers of ethylene with propylene and/or other alpha-olefins having a unique set of mechanical properties and thermoplastic processability. Of particular interest are devices for containing, administering, draining and transport of blood and biological and physiological fluids, syringe seals and similar applications.

Abstract: Amorphous propylene polymers are disclosed having the following characteristics:(a) intrinsic viscosity [.eta.]>1 d1/g;(b) %(r)-%(m)>0, wherein % (r) is the % of syndiotactic diads and %(m) is the % of isotactic diads;(c) less than 2% of the CH.sub.2 groups contained in sequences (CH.sub.2).sub.n, with n.gtoreq.2;(d) Bernoullianity index (B)=1.+-.0.2.These propylene polymers, which are in addition endowed with a narrow molecular weight distribution, can be obtained directly from the polymerization reaction of propylene as sole product and, therefore, do not require to be separated.

Abstract: A process for the preparation of an ethylene/1-butene or ethylene/1-butene/diene elastomer by slurry polymerization of the monomers in a polymerization medium consisting mainly of an excess of the 1-butene maintained in liquid form, performed in the presence of a catalyst based on a metallocene compound of Ti, Zr or Hf. This process is exempt from occurrence of reactor fouling and enables the recovery of the polymer without the use of steam as a stripping agent.

Abstract: Crystalline propylene polymers having P.I. values lower than or equal to 3.7, and having, at an MFR (Melt Flow Rate) ranging from 600 to 1000 g/10 min., an Mw value from 100,000 to 60,000, and at a MFR ranging from 1000 to 2000 g/10 min., an Mz value higher than or equal to 140,000, are obtained by way of polymerization with specific supported catalysts.

Abstract: Novel crystalline copolymers of propylene with minor proportions of ethylene and/or alpha-olefins, endowed with very good mechanical properties, a low melting point and a limited solubility in xylene at 25.degree. C., and the process for preparing them by means of the polymerization of mixtures of propylene with ethylene and/or alpha-olefins of suitable composition, by using catalysts obtained from stereorigid and chiral compounds of zirconium, and methylalumoxanic compounds.

Abstract: Spherical components of catalysts for the polymerization of olefins comprising:(a) a vanadium compound selected from the compounds of formula VOX.sub.2 Y or VX.sub.n Y.sub.n-4n, where X is Cl or Br and Y is Cl, Br OR or NR.sup.I.sub.2(b) MgCl.sub.2 in spherical form.Said components have an average diameter greater than 1 .mu.m, a surface area of at least 10 m.sup.2 /g, a porosity of at least 0.1 g/cm.sup.3 and an X-ray spectrum having particular characteristics.

Abstract: Crystalline propylene polymers having P.I. values lower than or equal to 3.7, and having, at an MFR (Melt Flow Rate) ranging from 600 to 1000 g/10 min., an Mw value from 100,000 to 60,000, and at a MFR ranging from 1000 to 2000 g/10 min., an Mz value higher than or equal to 140,000, are obtained by way of polymerization with specific supported catalysts.

Abstract: Disclosed is a catalyst for the polymerization of olefins, which includes the product of the reaction between an Al-alkyl compound and a solid catalyst component containing a magnesium halide in active form, a titanium compound and an electron-donor selected from the 1,3-diketones of formula: ##STR1## wherein the radicals R are the same or different, the radicals R.sup.I are the same or different, and R and R.sup.I are C.sub.1 -C.sub.20 alkyl, C.sub.3 -C.sub.20 cycloalkyl, C.sub.6 -C.sub.12 aryl, C.sub.7 -C.sub.20 arylalkyl or alkylaryl radicals or hydrogen, with the proviso that at least one of the R radicals is not hydrogen and can be bonded with the other R radical to form a cyclic structure, and at least one of the R.sup.I radicals, which are not bonded to one another to form a cyclic structure, is a branched alkyl, cycloalkyl or aryl radical, or is bonded to one or both R radicals to form a cyclic structure.

Abstract: Syndiotactic polymers of alpha-olefins selected from the group consisting of 1-butene, 4-methyl-1-pentene and 4-methyl-1-hexene and a method of preparation thereof by polymerizing said olefins with catalysts obtained from specific Zr or Hf cyclopentadienyl compounds and aluminoxane compounds.

Abstract: Disclosed are polymers and copolymers of CH.sub.2 .dbd.CHR alpha olefins where R is hydrogen or a 1-6 carbon atom alkyl radical, containing in the chain from 0.1 to 40 mole % of monomeric units ##STR1## where X is selected from the group consisting of (CH.sub.2).sub.r CH.sub.2 CH.sub.2 Y ##STR2## where r=0-10, Y is a halogen atom, R.sup.1 is a hydrocarbon radical with 1-18 carbon atoms.

Abstract: Polymers and copolymers of L(+) and D(-) lactic acid, with high molecular weight and in the absence of catalysts, are prepared by upgrading low molecular weight polymers in the solid state.

Abstract: Polyolefins stabilized against oxidation phenomena are obtained by using a process comprising the polymerization of monomers by way of a catalyst prepared by reacting an aluminum alkyl compound, and optionally an electron donor compound, with a solid component comprising a Ti compound and an electron-donor compound supported on magnesium chloride, the polymerization being carried out in the presence of one or more phenolic stabilizers and using, as electron-donor compound in the solid catalyst component, a compound selected from particular classes of ethers.

Abstract: Catalyst components for the polymerization of olefins obtained by reacting a tetravalent titanium halide or halogen alcoholate and an electron-donor compound with a porous polymer support on which is supported a magnesium dihalide or a magnesium compound which does not contain Mg--C bonds and can be transformed into a dihalide, characterized in that the Mg content before and after the reaction with titanium compound ranges from 6 to 12% by weight.

Abstract: Essentially syndiotactic crystalline copolymers of propylene with minor proportions of 1-butene, endowed with good mechanical properties, lowered melting point and limited solubility in xylene at 25.degree. C. and the process for their preparation by polymerizing mixtures of propylene with 1-butene, by using catalysts obtained form stereorigid and chiral zirconium and hafnium compounds and from polymethylalumoxane compounds.

Abstract: Functional polyolefins containing a terminal functional group; the block copolymers that can be obtained from such polyolefins by reaction with polymers reactive with the functional groups and the precursors used for the preparation of the functionalized polyolefins, which are made of olefin polymers terminated at one end with ZnR groups where R is an alkyl or aryl radical with 1-10 carbon atoms.

Abstract: Articles of syndiotactic styrene polymer where the polymer is present predominantly in a new crystalline form characterized by an X-ray spectrum which presents reflections of maximum intensity at 2 .theta.of 12.2.degree. and 20.0.degree., where in the 2 .theta. range from 15.degree. to 18.degree. no reflections of appreciable intensity appear.

Abstract: A process for the production of primarily syndiotactic vinyl aromatic polymers by polymerizing or copolymerizing vinyl aromatic monomers such as styrene or styrene derivatives in the presence of a catalyst system comprising the product of the reaction between:a) a compound of a transition metal (M) different from titanium and containing at least a bond M-O, M-C, M-N, M-P, M-S or M-halogen, andb) an organoaluminum compound containing at least an oxygen atom bound to the aluminum atom or bound between two aluminum atoms.Compound a) can be used as such or may be supported on a suitable carrier.

Abstract: Catalyst components for the polymerization of olefins comprising a titanium or vanadium compound supported on a porous particulate polymeric support which particles have a porosity greater than 0.3 cc/g and a pore distribution such that at least 40% of the pores have radius greater than 150 .ANG..The catalyst components are prepared by impregnating the polymeric support with a solution of the Ti or V compound and evaporating the solvent.

Abstract: Catalysts for the polymerization of olefins, comprising the product of the reaction between:A) a cyclopentadienyl compound of Ti, Zr or Hf;B) an alumoxane compound of formula: ##STR1## in which R.sup.1, R.sup.2, R.sup.3, R.sup.4, the same or different from each other, are alkyl, alkenyl or alkylaryl radicals having 2 to 20 carbon atoms.