Abstract: The invention relates to the use of 1,5-enediyne compounds of formula (I) as curing agents in polymeric systems. In particular the invention relates to a curable composition comprising a curing agent of formula (I) and a polymer suitable to be cross-linked and to the cured article obtained therefrom.

Abstract: The invention relates to the use of 1,5-enediyne compounds of formula (I) as curing agents in polymeric systems. In particular the invention relates to a curable composition comprising a curing agent of formula (I) and a polymer suitable to be cross-linked and to the cured article obtained therefrom.

Abstract: Peroxide-curable fluoroelastomeric compositions, consisting of a fluoroelastomer containing bromine, an organic peroxide and a metal-organic hydride having the formula: ##STR1## wherein M is selected from Sn, Si, Ge, Pb; x is an integer from 1 to 3; y, z are zero or integers from 1 to 3, with the proviso y+z=4-x; w is an integer from 1 to 3; the R groups, equal to or different from each other, are selected from: alkyls C.sub.1 -C.sub.4, aryls C.sub.6 -C.sub.12, arylalkyls and alkylaryls C.sub.7 -C.sub.14, optionally containing nitrile and/or hydroxyl groups. The hydride addition allows to increase the curing rate, obtaining at the same time a high crosslinking degree.

Abstract: Fluoroelastomers characterized by the presence of iodine or bromine atoms at the end of the polymeric chain in an amount equal to or lower than 1 iodine or bromine atom per polymeric chain, and by a bromine content in the chain ranging from 0.05 to 2% by weight referred to the total weight of the monomeric units.Said fluoroelastomers exhibit improved characteristics of processability, particularly as regards the utilization in injection molding processes and the detaching from the molds, as well as of stability to heat.A process for preparing fluoroelastomers containing iodine or bromine atoms at the ends of the polymeric chain, in an amount equal to or lower than 1 iodine or bromine atom per polymeric chain, which process comprises polymerizing mixes of fluorinated monomers (VDF, TFE, HFP, FVE) in bulk, in suspension, in aqueous emulsion, or in solution of organic solvents by means of radical starters, in the presence of compounds capable of providing I.sup.- or Br.sup.

Abstract: Fluoroelastomers characterized by the presence of iodine or bromine atoms at the end of the polymeric chain in an amount equal to or lower than 1 iodine or bromine atom per polymeric chain, and by a bromine content in the chain ranging from 0.05 to 2% by weight referred to the total weight of the monomeric units.Said fluoroelastomers exhibit improved characteristics of processability, particularly as regards the utilization in injection molding processes and the detaching from the molds, as well as of stability to heat.A process for preparing fluoroelastomers containing iodine or bromine atoms at the ends of the polymeric chain, in an amount equal to or lower than 1 iodine or bromine atom per polymeric chain, which process comprises polymerizing mixes of fluorinated monomers (VDF, TFE, HFP, FVE) in bulk, in suspension, in aqueous emulsion, or in solution of organic solvents by means of radical starters, in the presence of compounds capable of providing I.sup.- or Br.sup.

Abstract: A process for polymerizing or copolymerizing fluorinated monomers, in an aqueous dispersion, by using radicalic-type starters and fluorinated surfactants, characterized in that it is operated in the presence of a perfluoropolyether having neutral end groups and prepared in the form of an aqueous microemulsion, in order to increase the polymerization rate, to increase the process reproducibility and to minimize the consumption of said perfluoropolyether.

Abstract: A process for polymerizing or copolymerizing fluorinated monomers, in an aqueous dispersion, by the use of radicalic starters and of fluorinated surfactants, characterized in that it is operated in the presence of perfluoropolyether having neutral end groups, being liquid under the polymerization conditions and in the form of an aqueous emulsions, in order to increase the polymerization rate.

Abstract: Components of catalysts for polymerizing olefins having the general formula:VCl.sub.n (OR).sub.min which R=a hydrocarbon radical having 1-18 C; or R.sub.p.sup.1 Si(OH).sub.3-p, in which R.sup.1 =a hydrocarbon radical, 1.ltoreq.p.ltoreq.3; 1.5.ltoreq.n.ltoreq.3, m=3-n; with X-ray powder spectrum, in which maximum intensity diffraction lines, which in the spectrum of normal VCl.sub.3 appear at d=5.75 .ANG., d=2.67 .ANG. and d=1.74 .ANG., exhibit a broadening of the half peak breath of at least three times for the diffraction line at d=5.75 .ANG. and of at least four times for the diffraction lines appearing at d=2.67 .ANG. and d=1.74 .ANG., or said diffraction lines disappear.

Abstract: Catalyst-forming components are prepared from(a) a halogenated Ti compound containing at least a Ti-halogen bond;(b) an electron-donor compound free of active hydrogen atoms;and(c) the solid product of the reaction between at least one electron-donor compound containing active hydrogen atoms and a Mg dihalide or a complex thereof with an electron-donor compound free of active hydrogen atoms, obtained by decomposing organic Mg compounds containing at least one Mg-R or Mg-OR group, in which R is an alkyl, aryl, cycloalkyl or alkenyl radical having 1 to 20 carbon atoms, by means of a halogenating agent different from (a).Catalysts for polymerizing olefins and prepared by mixing the aforesaid catalyst-forming components with an organometallic compound of Al are also disclosed.

Abstract: Catalyst components which comprise the reaction product of a Ti compound and a Mg dihalide and which are in the form of spherical particles having an average diameter of 1 to 100 microns, a surface area of 300 to 500 m.sup.2 /g, and a porosity of 0.3 to 0.4 cc/g are disclosed, as are catalysts also in the form of spherical particles prepared therefrom and useful in the polymerization of ethylene and of alpha-olefins CH.sub.2 .dbd.CHR in which R is alkyl radical having from 1 to 6 carbon atoms, and the polymerization of the alpha-olefins therewith.

Abstract: Catalyst components for the polymerization of olefins are disclosed. Said components comprise the solid product of the reaction of a halogenated Ti compound and of an electron-donor compound not containing active H atoms with the solid product of the reaction between an electron-donor compound containing active H atoms and a Mg dihalide obtained by decomposition, with halogenating agents other than the above halogenated Ti compound, of product (d) obtained from the reaction between an organometallic Mg compound of formula R.sub.m MgX.sub.n is which R is a hydrocarbon or --OR group, X is halogen or a group R, OR, or COX' (X' being halogen), 0<m=2, 0<n<2 and m+n is 2; and a Si compound selected from polysiloxanes, hydropolysiloxanes, silanols and polysilanols.

Abstract: New and improved catalysts for polymerizing alpha-olefins of formula CH.sub.2 .dbd.CHR in which R is a C.sub.1 to C.sub.6 alkyl, more particularly propylene, mixtures of the alpha-olefins, and mixtures thereof with ethylene are disclosed. The catalysts are prepared from Al alkyl compounds and a solid product including a Mg dihalide and reaction products of said halide with at least one Ti compound and an electron donor compound which is an ester of an organic or inorganic oxygenated acid.