Abstract: Process for preparing polymer, e.g. polystyrene, particles that may not or may contain a water-retaining agent and that require only a one-step process for incorporating the water-retaining agent. The polymer particles may be prepared via an extrusion process, or a bulk polymerization process wherein a water-retaining agent is blended into the polymer melt. Water is incorporated into the particles by soaking them in hot or cold water or treating the particles with steam for a predetermined time depending on the desired water content in the particles. The water-retaining agent may be starch, zeolite, silica dioxide or poly (N-isopropyl acrylamide) ranging from 0.1% to 10.0% by weight. The particles can be expanded via appropriate means to form pre-expanded or expanded particles in a conventional manner.

Abstract: Process for preparing polymer, e.g. polystyrene, particles that may not or may contain a water-retaining agent and that require only a one-step process for incorporating the water-retaining agent. The polymer particles may be prepared via an extrusion process, or a bulk polymerization process wherein a water-retaining agent is blended into the polymer melt. Water is incorporated into the particles by soaking them in hot or cold water or treating the particles with steam for a predetermined time depending on the desired water content in the particles. The water-retaining agent may be starch, zeolite, silica dioxide or poly (N-isopropyl acrylamide) ranging from 0.1% to 10.0% by weight. The particles can be expanded via appropriate means to form pre-expanded or expanded particles in a conventional manner.

Abstract: A process for the manufacture of stable interpenetrating polymer blend networks is provided, comprising the preparation of a gel of a poly(alkylene) polymer by dissolving it in a mixture of one or more organic solvents and one or more vinyl aromatic monomers, optionally mixed with a compatible monomer, cooling this solution to a temperature of at most 80.degree. C., adding of a radical forming initiator for the polymerization of the vinyl aromatic monomer(s), homogenizig the solution, cooling the solution to a temperature to obtain gelation of the polyalkylene polymer in the solvent mixture, followed by heating the obtained gel to a temperature of at least 80.degree. C. and subsequently polymerization of the vinyl aromatic monomer(s) in bulk or suspending the heated solution in a vigorously stirred aqueous medium of a lower temperature to obtain gelation and polymerizing the suspended gel into polymer blend beads, stable interpenetrating polymer blend networks and intermediate gel used therewith.