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 invention relates to the production and use of block copolymers which are obtained by means of controlled radical polymerization in the presence of nitroxides for the purpose of reinforcing fragile polymer matrices. The invention offers advantages such as (i) simplicity of copolymer synthesis and use and (ii) fine dispersion of the copolymer molecules in the fragile matrix, which ensures both the transparency of the material and high reinforcement against impact. More specifically, the invention relates to the radical synthesis of block copolymers comprising at least three blocks, which include one block having a glass transition temperature of less than 0° C. and a thermoplastic end block having a glass transition temperature of more than 0° C., thereby guaranteeing compatibility with the fragile matrix to be reinforced against impact.

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: Thermoplastic composition comprising a (meth)acrylic (co)polymer and particles of hollow glass spheres—or a mixture of particles of hollow glass spheres and particles of a mineral and/or organic compound—the said particles scattering light: having a mean size of 0.5 ?m to 200 ?m; possessing a refractive index different from that of the transparent thermoplastic by at least ±0.05; and being used in an amount of 5 ppm to 1000 ppm by weight with respect to the total composition. Corresponding fashioned articles, especially sheets for backlight units.

Abstract: The invention relates to the production and use of block copolymers which are obtained by means of controlled radical polymerisation in the presence of nitroxides for the purpose of reinforcing fragile polymer matrices. The invention offers advantages such as (i) simplicity of copolymer synthesis and use and (ii) fine dispersion of the copolymer molecules in the fragile matrix, which ensures both the transparency of the material and high reinforcement against impact. More specifically, the invention relates to the radical synthesis of block copolymers comprising at least three blocks, which include one block having a glass transition temperature of less than 0° C. and a thermoplastic end block having a glass transition temperature of more than 0° C., thereby guaranteeing compatibility with the fragile matrix to be reinforced against impact.

Abstract: The invention concerns moulded discs for audio and/or optical information recording media (such as CDS and DVDs) obtained from a thermoplastic polymer material comprising, by weight, (a) 60 to 95%, preferably 70 to 85%, of a thermoplastic resin selected from (1) a methyl methacrylate homopolymer, (2) a copolymer containing in majority units derived from methyl methacrylate monomer, (3) a mixture of the homopolymer (1) and/or of the copolymer (2) with a substituted or unsubstituted styrene copolymer and of at least one monomer selected from (meth)acrylonitrile, maleic anhydride and maleimides or (4) a glutarimide polymer, optionally mixed with a substituted or unsubstituted styrene/(meth)acrylonitrile copolymer and (b) 5 to 40%, preferably 15 to 30%, of at least one impact modifier compound in the form of particles having an average size of between 10 and 200 nm, preferably between 40 and 150 nm.