Abstract: Pressure-sensitive "hot melt" adhesive compositions based on styrene-butadiene radial block copolymers, styrene-isoprene linear and/or radial block copolymers and plasticizing oils, are characterized in that they maintain low tack values (peeling, quick Stick) although having a good balance of properties normally required.

Abstract: A description follows of epoxydated block copolymers, either linear or branched, which can be defined with the following formulae:1) [A-(E-B-EPOX)].sub.n X2) A.sub.1 -(E.sub.1 -B.sub.1 -EPOX.sub.1)-A-HT-(E.sub.2 -B.sub.2 -EPOX.sub.2)3) [(E.sub.1 -B.sub.1 -EPOX.sub.1)-HT-A(E.sub.2 -B.sub.2 -EPOX.sub.2)].sub.n Xwhere A is a polyvinylaromatic block in a percentage ranging from 10 to 50% by weight, E-B-EPOX is a block composed of ethylene units, epoxydated butene and diene units in which the percentage by weight of the epoxy group ranges from 1% to 40%, HT is a tapered copolymer segment made up of hydrogenated and epoxydated diene monomeric units and vinylaromatic units whose content ranges from 0 to 20%, x is a radical having a valence ranging from 1 to 20.The block copolymers have an average molecular weight ranging from 30,000 to 400,000, a content of polyvinylaromatic blocks of between 10 and 50% by weight and a content of (E.sub.1 -B.sub.1 -EPOX.sub.1)+(E.sub.2 -B.sub.2 -EPOX.sub.

Abstract: A branched and hydrogenated block copolymer can be defined by the formula [(EB).sub.1 --HT--A--(EB).sub.2 ].sub.n X, where (EB).sub.1 and (EB).sub.2 are hydrogenated polydiene blocks, A is a polyvinylaromatic block, HT is a random copolymer segment made up of hydrogenated dienic monomeric and vinylaromatic units, X is a coupling radical having a valence equal to n, and n is a whole number ranging from 3 to 20.This kind of block copolymer shows excellent mechanical characteristics and resistance to atmospheric agents, even when used in combination with other resins.

Abstract: Perfluoropolyethers having fluorinated epoxy groups positioned along their perfluoropolyether chain, and free from peroxidic oxygen, are obtained by means of a low-temperature oxidation process, in the liquid phase, with molecular oxygen and in the presence of U.V. light, of a mixture of a perfluorinated monoolefin and a perfluorinated coniugated diene, and of the subsequent photochemical decomposition of the peroxy groups contained in the photoxidation product, carried out by treating the peroxy-groups-containing product with U.V. light at a temperature comprised within the range of from 0.degree. C. to 160.degree. C. Derivatives of said epoxy containing perfluoropolyethers in which the epoxy groups have been turned into functional groups.

Abstract: New perfluoropolyethers comprising repeating units chosen from among ##STR1## statistically distributed along the chain, having a controlled molecular weight and brominated end groups, prepared starting from the product of the photochemical oxidation of C.sub.2 F.sub.4, and/or C.sub.3 F.sub.6, containing peroxidic oxygen, and subsequent treatment in liquid phase with bromine, at temperatures ranging from -40.degree. to 130.degree. C. in the presence of ultraviolet radiations, said new perfluoropolyethers derivatives being useful as additives in rubber mixes vulcanizable with peroxides, in amounts of 0.01 to 5 parts by w per 100 parts by weight of elastomer, optionally in combination with non brominated perfluoropolyethers, to improve the processability in the extrusion and the detachability of the vulcanized articles from the molding.

Abstract: New perfluoropolyethers comprising repeating units chosen from among ##STR1## statistically distributed along the chain, having a controlled molecular weight and brominated end groups, prepared starting from the product of the photochemical oxidation of C.sub.2 F.sub.4, and/or C.sub.3 F.sub.6, containing peroxidic oxygen, and subsequent treatment in liquid phase with bromine, at temperatures ranging from -40 to 130.degree. C. with the presence of ultraviolet radiations, said new perfluoropolyethers derivatives being useful as additives in rubber mixes vulcanizable with peroxides, in amounts of 0.01 to 5 parts by w per 100 parts by weight of elastomer, optionally in combination with non brominated perfluoropolyethers to improve the processability in the extrusion and the detachability of the vulcanized articles from the molding.

Abstract: Perfluoropolyethers having fluorinated epoxy groups positioned along their perfluoropolyether chain, and free from peroxidic oxygen, are obtained by means of a low-temperature oxidation process, in the liquid phase, with molecular oxygen and in the presence of U.V. light, of a mixture of a perfluorinated monoolefin and a perfluorinated conjugated diene, and of the subsequent photochemical decomposition of the peroxy groups contained in the photooxidation product, carried out by treating the peroxy-groups-containing product with U.V. light at a temperature comprised within the range of from 0.degree. C. to 160.degree. C. Derivatives of said epoxy containing perfluoropolyethers in which the epoxy groups have been turned into functional groups.

Abstract: The process for the scission of high molecular weight perfluoropolyethers having neutral end groups obtained from photo-oxidation processes of perfluoroolefins, or fluorination of hydrogenated polyalkylene oxides, or by polymerization with opening of the partially fluorinated oxetane ring, the scission being carried out in the presence of catalysts selected from the group consisting of fluorides, oxyfluorides and oxides of transition metals, or selected from the group consisting of Al, Sn, and Sb, at temperatures ranging from 150.degree. to 380.degree. C. The scission process leads to the formation of low molecular weight perfluoropolyethers having neutral and acid end groups, the perfluoropolyetheral acids being subjected to conversion reactions in order to obtain functionalized perfluoropolyethers. The products can be used as operative fluids for high vacuum pumps.

Abstract: A process for the dissociation of high molecular weight perfluoropolyethers to obtain low molecular weight perfluoropolyethers which comprises treating a perfluoropolyether with 0.1-10% by weight of a catalyst consisting of Ti, Cr, Mn, Fe, Co, Ni, V, Cu, Mo, Sn, Sb, Zr, Zn oxides at temperatures comprised between 150.degree. and 380.degree. C.

Abstract: A process for decomposing perfluoropolyethers to products with a controlled molecular weight, comprising heating the perfluoropolyethers at temperatures of from 150.degree. to 380.degree. C. with 0.1%-2% by weight of a catalyst comprising a fluoride and/or oxyfluoride of Al, Ti, V, Co or Ni; and in case to fluorination at high temperatures to obtain completely neutral perfluoropolyethers.

Abstract: A process for the scission of high molecular weight perfluoropolyethers having neutral end groups obtained from photo-oxidation processes of perfluoroolefins, or fluorination of hydrogenated polyalkylene oxides, or by polymerization with opening of the partially fluorinated oxetane ring, said scission being carried out in the presence of catalysts composed of fluorides, oxyfluorides, or oxides of transition metals, or of Al, Sn, Sb, at temperatures ranging from 150.degree. to 380.degree. C.; said scission process leads to the formation of low molecular weight perfluoropolyethers having neutral and acid end groups, the perfluoropolyethereal acids being subjectable to conversion reactions in order to obtain functionalized perfluoropolyethers and to be utilized to provide new polymers.

Abstract: A method of preparing perfluoropolyethers having a regulated molecular weight starting from the product obtained by photochemical oxidation of C.sub.2 F.sub.4 and having a various content of oxygen peroxide, consisting in heat-treating the peroxidized product in order to partially remove the oxygen peroxide till reducing it to a relatively low value, which is prefixed as a function of the molecular weight to be obtained for the final product, and in the subsequent treatment with gaseous fluorine at high temperatures.

Abstract: Neutralization of perfluoropolyethers is accomplished by reacting them with gaseous fluorine in the presence of radiations having a wavelength from 200 to 300 nm. The presence of radiations permits to operate at lower temperatures and with higher reaction rates, and to reach an exhaustive neutralization.

Abstract: Perfluoropolyether comprising, besides --CF.sub.2 -- and --CF.sub.2 F.sub.4 units, also a third fluoroalkylene unit containing three or more carbon atoms, said units being connected to each other through --O-ether bridges, and process for obtaining above said polyether, consisting in reacting a mixture of polyperoxidic perfluoropolyether and a fluorinated olefin, in the presence of U.V. radiations.