Abstract: Expandable vinylaromatic polymers which comprise: a) a matrix obtained by polymerizing 50-100% by weight of one or more vinylaromatic monomers and 0.50% by weight of a copolymerizable monomer; b) 1-10% by weight, calculated with respect to the polymer (a), of an expanding agent englobed in the polymeric matrix; c) 0.05-25% by weight, calculated with respect to the polymer (a), of an inorganic filler homogeneously distributed in the polymeric matrix with a substantially spherical granulometry, an average diameter ranging from 0.01 to 100 ?m, a refraction index higher than 1.6 and a white index, as defined in “Colour Index” (third edition published by the Society of Dyers and Colourists, 1982), equal to or lower than 22.

Abstract: Compositions of expandable vinylaromatic polymers which contain a polymer, of at least one vinylaromatic monomer, having an average molecular weight Mw ranging from 50,000 to 170,000, which comprise: a) 0-50% by weight of a copolymer obtained by polymerizing one or more vinylaromatic monomers and 0.1-15% by weight of an ?-alkylstyrene; b) 0-10% by weight of a compatible polymer having a crystallinity lower than 10% and a glass transition temperature (Tg) higher than 100° C., the remaining percentage consisting of the vinylaromatic polymer; c) 2-10% by weight, calculated with respect to the total, of an expanding agent; with the proviso that at least one of (a) or (b) is present in the polymeric mixture.

Abstract: Expandable vinylaromatic polymers which comprise: a) a matrix obtained by polymerizing 50-100% by weight of one or more vinylaromatic monomers and 0.50% by weight of a copolymerizable monomer; b) 1-10% by weight, calculated with respect to the polymer (a), of an expanding agent englobed in the polymeric matrix; c) 0.05-25% by weight, calculated with respect to the polymer (a), of an inorganic filler homogeneously distributed in the polymeric matrix with a substantially spherical granulometry, an average diameter ranging from 0.01 to 100 ?m, a refraction index higher than 1.6 and a white index, as defined in “Colour Index” (third edition published by the Society of Dyers and Colourists, 1982), equal to or lower than 22.

Abstract: Compositions of expandable vinylaromatic polymers which contain a polymer, of at least one vinylaromatic monomer, having an average molecular weight Mw ranging from 50,000 to 170,000, which comprise: a) 0-50% by weight of a copolymer obtained by polymerizing one or more vinylaromatic monomers and 0.1-15% by weight of an ?-alkylstyrene; b) 0-10% by weight of a compatible polymer having a crystallinity lower than 10% and a glass transition temperature (Tg) higher than 100° C., the remaining percentage consisting of the vinylaromatic polymer; c) 2-10% by weight, calculated with respect to the total, of an expanding agent; with the proviso that at least one of (a) or (b) is present in the polymeric mixture.

Abstract: Beads of expandable vinylaromatic polymers which comprise: a) a matrix obtained by polymerizing 50-100% by weight of one or more vinylaromatic monomers and 0-50% by weight of at least one copolymerizable monomer; b) 1-10% by weight, calculated with respect to the polymer (a), of an expanding agent englobed in the polymeric matrix; c) 2 ppm-2% by weight, calculated with respect to the polymer (a), of an anti-lumping additive, distributed an the surface of the beads, comprising Oxides of metals of groups IB, IIB and VIIB.

Abstract: Process for the preparation of expandable vinylaromatic polymers which comprises: a) polymerizing in aqueous suspension at last one vinylaromatic monomer in the presence of a suspending agent selected from inorganic salts of phosphoric acid; b) recovering the expandable beads from the reaction container; c) washing the beads thus obtained with an aqueous solution containing 0.005-2% by weight of a non-ionic surface-active agent; d) recovering the washed beads substantially without any inorganic salt of phosphoric acid, on the surface, and drying them in a stream of air.

Abstract: Expandable vinylaromatic polymers which comprise: a) a matrix obtained by polymerizing 50-100% by weight of one or more vinylaromatic monomers and 0.50% by weight of a copolymerizable monomer; b) 1-10% by weight, calculated with respect to the polymer (a), of an expanding agent englobed in the polymeric matrix; c) 0.05-25% by weight, calculated with respect to the polymer (a), of an inorganic filler homogeneously distributed in the polymeric matrix with a substantially spherical granulometry, an average diameter ranging from 0.01 to 100 &mgr;m, a refraction index higher than 1.6 and a white index, as defined in “Colour Index” (third edition published by the Society of Dyers and Colourists, 1982), equal to or lower than 22.

Abstract: Process for producing foamable particles of styrenic polymers, which consists in submitting said particles to a partial loss of foaming agent, performed in an oven at a lower temperature than the glass transition temperature (Tg) of said particles.