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 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 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: 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.

Abstract: Mechanically strong; heat-resistant and transparent PMMA polymers having a high content of syndiotactic triads, a number average molecular weight ranging from 5,000 to 500,000 and a polydispersity index ranging from 1.01 to 1.5, are prepared by anionically polymerizing methyl methacrylate, characteristically at a temperature of at least 0.degree. C., in the presence of (a) at least one organolithium or organosodium initiator and (b) at least one AlR.sup.1 R.sup.2 R.sup.3 ligand, for example at least one di- or tri-phenoxy alkyl aluminum compound.

Abstract: Inhibition of the formation of unsaturated carbon compounds during the heating of 141b by the use of a vessel pre-treated with HF to form an iron fluoride coating on the internal surfaces of said vessel.

Abstract: The present invention relates to an insulating composition for electrical cable comprising a mixture of an ethylene-alkyl acrylate or ethylene-vinyl acetate copolymer and of a polymeric compound, said polymeric compound being an ethylene-alkyl acrylate-maleic anhydride terpolymer or an ethylene-vinyl acetate-maleic anhydride terpolymer, and usual additives such as, for example, a crosslinking agent, its use for the preparation of an insulation sheath of electrical cables and the insulation sheath obtained.

Abstract: The invention relates to a continuous process for the preparation of perfluoroalkyl iodides by thermal telomerization, in the gas phase, of tetrafluoroethylene with pentafluoroethyl iodide or heptafluoroisopropyl iodide in a tubular reactor.To improve the selectivity for a telomer of the desired extent, the telomers of lesser extent are recycled to at least one point in the reactor, which is situated between one-twentieth and three-quarters the length of the tube.

Abstract: The invention relates to a process for preparing 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 composite tubular article is prepared such that it consists of an inner layer of thermoplastic elastomer containing polyamide blocks sheathed by extrusion at an appropriate temperature with 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. Optionally, an innermost layer consisting of a thermoplastic with good liquid-barrier properties is present. The composite tubular article obtained is vulcanized, preferably at a temperature of between -5.degree. C. and +30.degree. C. in relation to the Vicat point of the said thermoplastic elastomer containing polyamide blocks.

Abstract: A novel and safe ethylenically unsaturated peroxyester composition derived from an ethylenically unsaturated dicarboxylic acid is provided, as well as processes for making and using the composition. The peroxyester composition comprises about 0.04 to about 0.70 mole fraction of a first component compound having a formula I: ##STR1## about 0.32 to about 0.50 mole fraction of a second component compound having a formula II: ##STR2## about 0.04 to about 0.70 mole fraction of a third component compound having a formula III: ##STR3## wherein Q is an unsaturated ethylene divalent radical and R.sup.1 and R.sup.2 are organic substituents. Polymeric-peroxides are prepared via polymerizing the peroxyester compositions. The peroxyester compositions are also used for curing unsaturated polyester resins and for initiating polymerization of ethylenically unsaturated monomers.

Abstract: Process for synthesizing 1,1,1-trifluoroethane (143a) in the gaseous phase by reacting 1,1-defluoro-1-chloroethane in gaseous phase in the presence of a Cr catalyst. The process may be run isothermally or adiabatically, without co-feeding air or other oxygen containing gas, in the presence or absence of a Ni, Co, Zn or Mn cocatalyst for the Cr catalyst. The catalyst may be unsupported or supported with a support preferably selected from activated carbon, alumina and fluorided alumina. The formation of olefin byproduct can be kept to less than 10 ppm in accordance with the process of the invention.

Abstract: The invention relates to a process for the alcoholysis of carbon tetrachloride which consists in simultaneously sending, on the one hand, carbon tetrachloride and, on the other hand, an alcohol ROH, over a catalytic composition, characterized in that the said catalytic composition comprises an aqueous solution of a metal halide.

Abstract: Compounds of formula (I) are disclosed: ##STR1## wherein L.sup.1 is a main group atom, L.sup.2 is a neutral ligand, M is a transition element or a metal element of Group 13, 14, 15, or 16 of the Periodic Table, x is the number of coordination sites of M, R.sup.1 is a polymerizable group, R.sup.2, R.sup.3, and R.sup.4 are ligands, and R.sup.5 is an anionic ligand. The compounds or monomers of formula (I) are capable of conversion to polymers by combination with one or more other known monomers, such as methyl methacrylate. Such polymers can then be added as a binder in a paint formulation to make marine antifouling coating compositions. Also described is a method to prevent fouling on surfaces wherein a composition containing a metal complex compound of formula (II): ##STR2## wherein M, x, L.sup.2, n, and R.sup.4 have the same meaning as in formula (I), is applied to the surface susceptible to fouling.

Abstract: Composite including a rubber/thermoplastic blend adherent by itself to a thermoplastic material; the blend is in the form of a thermoplastic matrix containing rubber nodules functionalized and vulcanized during the mixing with the thermoplastic. Composite articles obtained by overmoulding the vulcanized rubber/thermoplastic blend onto the thermoplastic.

Abstract: A compound (I) is prepared by reaction of at least one (meth) acrylate (II) with a heterocyclic alcohol (III), in the presence of at least one catalyst chosen from the chelates of calcium with 1,3-dicarbonyl compounds, such as calcium acetylacetonate. ##STR1## R.sup.1 =H, CH.sub.3 ; A, B=C.sub.2 -C.sub.5 alkylene; R.sup.2 =C.sub.1 -C.sub.4 alkyl.

Abstract: The invention relates to a star block copolymer of the formula [S.sub.1 -S.sub.2 -(B.sub.1 /S.sub.3)-B.sub.2 ].sub.m -X-[B.sub.2 (B.sub.1 /S.sub.3)-S.sub.2 ].sub.n in which X represents a polyfunctional radical resulting from a coupling agent, m and n represent non-zero integers such that m+n is equal to 3 or 4, S.sub.1 and S.sub.2 each represent a block of a polymer containing at least one vinylaromatic monomer, B.sub.2 represents a block of a polymer containing at least one conjugated diene, (B.sub.1 /S.sub.3) represents a block of a statistical copolymer containing at least one vinylaromatic monomer and at least one conjugated diene, 40 to 75% by weight of (B.sub.1 /S.sub.3) consisting of resulting from vinylaromatic monomer, characterized in that the sum of the mass of the blocks B.sub.2 contains more than 40% by weight and less than 90% by weight of the total mass of the conjugated diene contained in the said star block copolymer. The invention also relates to the process for obtaining this copolymer.

Abstract: A multifunctional anionic polymerization initiator which is in the form of a star-shaped polymer soluble in an apolar medium and substantially free of residual double bonds. The initiator is denoted by the general formula (PA).sub.a N.sup.n- nLi.sup.+. PA is a polymer block of a vinylaromatic or diene monomer A. The variable "a" is the number of branches in the block PA. N is a crosslinked core comprising no or practically no residual double bonds and has the formula (PMc)(RLi).sub.p. Mc is a monomer containing at least two polymerizable double bonds per molecule. PMc is a crosslinked core of at least one polymerized monomer Mc, containing 3 to 30% of residual double bonds in relation to the initial double bonds originating from the monomer Mc. R is an alkyl, aryl, arylalkyl, alkylaryl, cycloalkyl, or alkenyl. The variable "p" is the number of residual double bonds in PMc which are neutralized by RLi. The variable "n" is the number of anionic sites present in the crosslinked core N.

Abstract: The initiating system for the anionic polymerization of acrylic monomers, and where necessary, vinyl comonomers, including at least one R-M initiator in which M=a metal chosen from among the alkaline and alcaline earth metals and R=an alkyl with a linear or branched chain at C.sub.2 -C.sub.6 or aryl or arylalkyl, is characterized by the fact that the polymerization takes place in the presence also of at least one R.sub.1 OM.sub.1 alkaline metal alcoholate, in which R=an alkyl with a linear or branched chain at C.sub.1 -C.sub.6 or aryl or aryalkyl and M.sub.1 =an alkaline metal, on condition that when M.sub.1 is lithium, then R=an aryl or arylalkyl. Said process for the polymerization of primary, secondary, or tertiary alkyl acrylates, and possibly of vinyl comonomers, is characterized by the fact that the polymerization takes place in the presence of an initiating system as described above.

Abstract: The invention relates to a coating composition for PVC sections, based on a polymeric vehicle, a crosslinking agent, and a thermoplastic resin powder. The coating composition is particularly useful for coating PVC sections for windows, shutters, and doors. PVC joinery coated with the composition of the invention has exceptional impact strength and resistance to abrasion, friction, and inclement weather.