US Patent 7612119 Expandable vinylaromatic polymers and process for their preparation

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) 0.01-20% by weight, calculated with respect to the polymer (a) of carbon black distributed in the polymeric matrix having an average diameter ranging from 30 to 2000 nm, a surface area ranging from 5 to 40 m2/g, a sulfur content ranging from 0.1 to 2000 ppm and an ash content ranging from 0.001 to 1%.