Abstract: Poly(alkyl (meth)acrylates) are inexpensively prepared, even on an industrial scale, by anionically polymerizing at least one alkyl (meth)acrylate monomer in the presence of a lithium-based initiator and in a liquid solvent medium in which the solubility parameter .delta. is less than 20, said initiator comprising an alcoholate having the formula ROLi, wherein R has the formula R.sup.1 (OR.sup.2).sub.m, in which R.sup.1 is a linear or branched alkyl radical having from 2 to 4 carbon atoms, R.sup.2 is a linear or branched alkylene radical having from 2 to 4 carbon atoms, and m is 1, 2 or 3.

Abstract: The invention relates to the purification of pentafluoroethane (F125) containing chloropentafluoroethane (F115) by vapor-phase catalytic hydrogenolysis.A catalyst based on palladium deposited on aluminium trifluoride is employed.

Abstract: A diblock copolymer obtained by polymerizing acrylic, methacrylic or nonacrylic vinyl monomers in the presence of a polymerization initiating amount of an initiation system including (1) at least one functional initiator and (2) an alkali metal alcoholate. The alcoholate has the formula:R'OM'in which M' is an alkali metal and R' has the formula:R.sup.1 (OR.sup.2).sub.min which R.sup.1 is a linear or branched alkyl radical containing from 1 to 6 carbon atoms or an arylalkyl radical, R.sup.2 is a linear or branched alkylene radical containing from 2 to 4 carbon atoms, and m is the integer 1, 2 or 3.

Abstract: Bifunctional primer naphthalene compounds having the formula: ##STR1## wherein M" is an alkali metal, preferably sodium or lithium, and R.sup.1 and R.sup.2 are, e.g., alkyl radicals, are prepared from corresponding 1,5-diethenylnaphthalene derivatives, and are well suited for the improved anionic polymerization of diene, vinylaromatic and/or (meth)acrylic monomers.

Abstract: The invention relates to a continuous process for the preparation of aluminum nitride by the carbonitriding of alumina. According to this process, a reaction that uses alumina, carbon, and a resin that generates carbon by pyrolysis is performed in a methodical reactor. The invention relates to a continuous process for the preparation of aluminum nitride by the carbonitriding of alumina.

Abstract: The invention relates to a translucent and flexible polyamide-based composition, which is easy to process, in particular by extrusion, comprising: (A) from 50 weight-% to 95 weight-% 1) of at least one polyamide resin (I), 2) of various additives (IV) such as stabilizers, mould-release agents, lubricants, crystallization accelerators, pigments, organic and/or inorganic fillers or dyes, or antioxidizing agents, 3) optionally of at least one plasticizing agent (V), and (B) from 5 weight-% to 50 weight-%: (a) of at least one ethylene-alkyl (meth)acrylate-unsaturated dicarboxylic acid anhydride terpolymer (II), (b) of at least one ethylene-alkyl (meth)acrylate copolymer (III) with 1/30.ltoreq.(b)/(a).ltoreq.2. In accordance with the present invention, the flexural modulus of the composition, measured according to ISO standard 178, is less than or equal to 2/3 of the flexural modulus of the PA resin (I) alone and is strictly less than 750 MPa.

Abstract: Anionic waterborne polyurethane dispersions made using hydroxyl terminated polybutadiene resins and use of the dispersions to make films and adhesives.

Abstract: The invention relates to the gas-phase hydrogenolysis of chlorofluorocarbons or of chlorofluorohydrocarbons in the presence of a palladium-based catalyst deposited on a support in which sulfur is incorporated into the catalyst in order to stabilize the catalytic activity.

Abstract: This process for the preparation of isobornyl (meth)acrylate by reaction of (meth)acrylic acid with camphene consists in blending the reactants in a blending tank and in placing the mixture in contact with the catalyst in a cartridge which is separate from the blending tank.Single figure.

Abstract: The aldolization is characterized by the use of a solid basic catalyst which has the following general formula?(Mg.sup.2+).sub.1-x (Al.sup.3+).sub.x (OH.sup.-).sub.2 !.sup.+x ?(OH.sup.-).sub.x (H.sub.2 O).sub.n !.sup.-x (II)wherein 0.20.ltoreq.x.ltoreq.0.33 and n has a value of less than 1. This catalyst has a defined crystal structure similar to that of hydrotalcite or, alternatively, of meixnerite. Also disclosed are processes for the preparation of the catalyst.

Abstract: The invention concerns the anionic polymerization of alkyl methacrylate in the presence of a priming system. The priming system comprises an organolithium primer and an organic compound of aluminum and pyridine. This priming system allows better polymerization control.

Abstract: Living random (meth)acrylic copolymers, facilely converted into random co(meth)acrylates and block copolymers thereof, comprise the anionic copolymerizates of at least one comonomer A with at least one comonomer B selected from among the (meth)acrylates and maleimides, at least one of the comonomers A and B comprising a (meth)acrylate, in the presence of (i) at least one alkali or alkaline earth metal, mono- or difunctional initiator and (ii) at least one ligand, for example a nonnitrogenous macrocyclic complexant, e.g., a crown ether, or an alkali metal alcoholate.

Abstract: This invention relates to compositions resulting from the reaction, in aqueous phase, of aluminum hydroxide, of alkali metal cation hydroxide and of calcium or strontium hydroxide. The addition of such a composition to PVC resins or to olefinic resins from Ziegler catalysis prevents the degradation of these resins under the effect of light or of heat, in particular during extrusion.

Abstract: Novel N-substituted maleimide homopolymers having a number-average molecular weight ranging from 12,000 to about 100,000 are prepared by anionically polymerizing an N-substituted maleimide monomer, in solvent phase, in the presence of at least one organometallic polymerization initiator which comprises sec-butyllithium, a sodium alcoholate, diphenylmethylpotassium, naphthalenelithium or naphthalenesodium, and novel N-substituted maleimide homopolymers having a polydispersity index ranging from 1.1 to 1.5 are prepared by anionically polymerizing an N-substituted maleimide monomer, in solvent phase, in the presence of at least one alkali metal organometallic polymerization initiator and at least one inorganic or organic salt of an alkali or alkaline earth metal; novel block copolymers include blocks of the above maleimido homopolymers and, e.g., blocks of an acrylic or methacrylic polymer.

Abstract: Disclosed are polymers and copolymers containing at least one repeating unit of the formula ##STR1## in which X is O or NH; R is a single bond or a hydrocarbon chain; R' is a hydrocarbon chain containing one or two carbon atoms, and P is the residue of an oligomer HX--P--XH whose solution viscosity determined in meta-cresol at 30.degree. C. at concentrations of 0.5 g/dl is lower than 0.50 dl/g.sup.-1. Also disclosed is a process for obtaining the polymers and copolymers.

Abstract: The invention relates to a composite tubular article consisting of a vulcanized elastomer containing carboxylic acid or dicarboxylic acid anhydride functional groups, which is used in combination with a thermoplastic elastomer containing polyamide blocks. The invention also relates to a process for the preparation of such articles, characterized in that a tube consisting of an outer layer of thermoplastic elastomer containing polyamide blocks and optionally an inner layer consisting of a thermoplastic with good liquid-barrier property is sheathed by extrusion at an appropriate temperature of an elastomeric composition comprising a synthetic or natural elastomer containing carboxylic acid or dicarboxylic acid anhydride functional groups, a crosslinking system and optionally various adjuvants and fillers, in that the composite tubular article obtained is vulcanized, preferably at a temperature of between -5.degree. C. and +30.degree. C.

Abstract: Compounds represented by the formulae (I) and (II) in which:R.sup.1 =H or CH.sub.3 ;X=O or S;R.sup.2 =C.sub.1-12 straight-chain or branched alkylene groups, monocyclic or polycyclic cycloalkylene and heterocycloalkylene groups, alkylarylene and arylalkylene groups;R.sup.6 =H or C.sub.1-12 alkyl and aryl radicals;R.sup.3 =C.sub.1-20 alkyl and aryl radicals, --(CH.sub.2).sub.p SR.sup.4 groups where p=integer from 2 to 12 and R.sup.4 =C.sub.1-20 alkyl, and ##STR1## where q is an integer from 2 to 12 and R.sup.5 =H or CH.sub.3.

Abstract: The present invention relates to a new process for the manufacture of fine powder of silicon nitride, to this powder and to the sinters obtained from the latter. The process comprises the reaction, in a nitrogen countercurrent and in continuous fashion, of silica, carbon and a seed crystal, in the presence of a volatile compound of a metal chosen from the group consisting of Be, Mg, Ca, Sr, Ge, Sn, Ti, Hf, Na and Ba, in a reaction zone possessing a temperature gradient, comprising a hot zone in which the said metal compound passes into the gaseous state and a cold zone in which the said metal compound in the gaseous state condenses, the said metal compound in the gaseous state being carried from the hot zone to the cold zone by the nitrogen countercurrent.

Abstract: The present invention relates to a thermoplastic film including at least one ethylene copolymer, which film is capable of being sealed by a high-frequency current. The film is characterized by its inclusion of a sufficient quantity of at least one N,N'-ethylenebisamide in order to obtain a high-frequency sealing time not exceeding 1 second. The films thus sealed are especially useful for packaging.

Abstract: An acrylic acid ester is manufactured by reaction of the said acid and an alcohol chosen from C.sub.