Abstract: Process for processing expandable polymer particles e.g. polystyrene (EPS) that eliminates the maturing step between the pre-expander and molding steps. The expandable particles are first over pressurized with gas, e.g. air, carbon dioxide, nitrogen, and mixtures thereof, at a pressure between 500 and 8000 kPa and a temperature between ?20° C. and 130° C. for 15 to 7200 minutes to create a gas pressure in the particles. Using the gas pressure in the particles, pre-expanding the particles with a heating medium, e.g. steam at a temperature between 100° C. and 120° C. and at a pressure ranging above atmospheric pressure and below the gas pressure in said particles, i.e. 50 to 200 kPa for 5 to 120 seconds. The pre-expanded particles are air dried in the pre-expander while holding a positive pressure in the particles; are optionally transferred to a pressure silo; and then are transferred to a molding machine where the gas pressure in the particles is used to form a foam article.

Abstract: Process for the preparation of expandable polyvinylarene particles in which compact polyvinylarene particles are impregnated by an inorganic N2- and/or O2-containing gas at a temperature below 95° C. and at a pressure of 100 to 2,000 kPa gauge.

Abstract: Polymer particles containing a polymer of a vinylarene monomer, a porous silicate compound and at least 1.5% by weight of water, based on the weight of vinylarene, water and porous silicate compound, wherein the porous silicate compound is selected from alumino silicates and amorphous silica particles, and a process for the preparation of such polymer particles.

Abstract: Process for the preparation of expanded polyvinylarene particles in which polyvinylarene particles pre-expanded to an apparent density do ranging between 600 and 200 kg/m3 are impregnated by an inorganic gas, and the impregnated particles thus obtained are expanded to an apparent density of at least three times lower than do.