Abstract: Process for the preparation of impact-strengthened cast PMMA sheets comprising the following stages: 1. a mixture comprising: at least one alkoxyamine Z(-T)n, in which Z denotes a polyvalent group and n an integer greater than 2, preferably of between 2 and 10, advantageously between 2 and 8, and the monomer(s) intended to form a central block B is heated to a temperature sufficient to activate the alkoxyamine and polymerize the monomer(s); 2. the central block B, optionally mixed with the unconsumed monomer(s) from stage 1, is reactivated in the presence of the monomer(s) intended to form the branches A; 3. MAM and optionally at least one comonomer M which can be copolymerized by the radical route with MMA and at least one radical initiator are added to the mixture obtained in stage 2; 4. the mixture from stage 3 is cast in a mould and then heated.

Abstract: Process for the preparation of impact-strengthened cast PMMA sheets comprising the following stages: 1. a mixture comprising: at least one alkoxyamine Z(-T)n, in which Z denotes a polyvalent group and n an integer greater than 2, preferably of between 2 and 10, advantageously between 2 and 8, and the monomer(s) intended to form a central block B ?is heated to a temperature sufficient to activate the alkoxyamine and polymerize the monomer(s); 2. the central block B, optionally mixed with the unconsumed monomer(s) from stage 1, is reactivated in the presence of the monomer(s) intended to form the branches A; 3. MAM and optionally at least one comonomer M which can be copolymerized by the radical route with MMA and at least one radical initiator are added to the mixture obtained in stage 2; 4. the mixture from stage 3 is cast in a mould and then heated.

Abstract: The heat and light stability imparted to vinyl halide polymers by metal compounds conventionally employed for this purpose is considerably improved by the presence of a mercapto ester such as 2-mercaptoethyl stearate. The esters can replace a substantial portion of the metal compound with no significant reduction in stability.

Abstract: Light-scattering methacrylic polymer material comprising: from 80 to 90% of a methacrylic (co)polymer; from 5 to 15% of a compatible fire retardant chosen from a halogenated polyphosphonate and a halogenated neutral ester compound of phosphoric acid; and from 1 to 5% of a silica having an elementary particle size of less than 500 nm.

Abstract: Adhesive compositions based on polyurethane and a polyamine suspension have a free isocyanate functional group content of between 2 and 9% by weight, with the polyamine being in the form of particles having a mean diameter of between 30 and 60 &mgr;m. A process for preparing the adhesive compositions involves reacting a polyol and a polyisocyanate to form a polyurethane prepolymer, wherein the prepolymer is mixed with the polyamine suspension. The adhesive compositions can be used for the adhesive bonding of materials, especially for motor vehicles.

Abstract: The present invention relates to crosslinkable hot-melt adhesive compositions in the form of prepolymer containing free isocyanate functional groups; the said prepolymer results from the reaction of a polyisocyanate and of a copolymer (A) of ethylene and of at least one unsaturated carboxylic acid ester and containing hydroxyl functional groups. These adhesives are crosslinked by the ambient moisture.

Abstract: The invention relates to adhesive compositions based on polyurethane and on a polyamine suspension, characterized in that the free isocyanate functional group content is between 2 and 9% by weight and the polyamine is in the form of particles of mean diameter between 30 and 60 .mu.m. Its subject-matter is also a process for the preparation of the said compositions which consists in reacting a polyol and a polyisocyanate to form a polyurethane prepolymer, which prepolymer is mixed with the polyamine suspension.Such compositions can be employed for the adhesive bonding of materials especially for motor vehicles.

Abstract: The present invention relates to hot-melt adhesive compositions based on copolymers of ethylene, vinyl acetate and vinylalkoxysilane units, which are crosslinkable by moisture, wherein the hot-melt adhesive is substantially anhydrous. More particularly, it relates to the storage stability of the hot-melt adhesive compositions including at least one crosslinking catalyst. The invention also relates to a process for the manufacture of the hot-melt adhesive composition comprising drying the hot-melt adhesive under vacuum at a temperature lower than 180.degree. C. and purging with a dry gas at a temperature lower than 180.degree. C.

Abstract: Unique hot-melt adhesive compositions that irreversibly crosslink in a few days in the presence of atmospheric moisture comprise a polyisocyanated EVA terpolymer having a melt index at 190.degree. C. ranging from 100 to 1,000, such polyisocyanated terpolymer comprising (1) from 60% to 90% by weight of ethylene, (2) from 10% to 40% by weight of vinyl acetate and (3) from 5 to 60 meq. OH of an ethylenically unsaturated termonomer bearing at least one primary hydroxyl functional group per mole, and the composition being essentially devoid of free hydroxyl functional groups.

Abstract: A process for the sterilization of objects made of polymers in which the molecule contains a halogen, or of products packaged in such polymer material, the polymer containing a heat stabilizer wherein, prior to irradiation of the object or the package and its contents, there is incorporated into the polymer one or more esters carrying at least one mercaptan function in the proportion of one --SH group for 3 to 10 carbon atoms.

Abstract: The process concerns stabilization of polymers against ionizing radiation where the polymer molecule contains a halogen. It comprises incorporating hydroquinone into the polymer, especially into polyvinyl chloride, the polymer containing both a metallic compound, heat stabilizer, and also a mercaptan.

Abstract: The present invention is related to a process for absorbing acid gases from industrial gaseous mixtures by washing under pressure with a solvent. The invention is concerned more particularly with the use of hexamethyl phosphorotriamide OP[N(CH.sub.3).sub.2 ].sub.3, pure or mixed with water, as a physical solvent of acid gases.This new physical solvent is of particular interest in the treatment of natural acid gases and refinery gases.

Abstract: H.sub.2 S is removed from gas containing CO.sub.2 by a thioether, thioamide or alkyl thiocarbonate solvent.