Abstract: Particulate polystyrene containing blowing agent and having improved expandability is based on polystyrene having a weight-average mean molecular weight of not more than from 130,000 to 180,000 and a molecular weight distribution curve in which the high molecular weight flank drops steeply. The expandable polystyrene particles are produced by polymerizing styrene in aqueous suspension in the presence of blowing agents and of chain transfer agents or styrene oligomers.

Abstract: Particulate polystyrene containing blowing agent and having improved expandability is based on polystyrene having a weight-average mean molecular weight of not more than from 130,000 to 180,000 and a molecular weight distribution curve in which the high molecular weight flank drops steeply. The expandable polystyrene particles are produced by polymerizing styrene in aqueous suspension in the presence of blowing agents and of chain transfer agents or styrene oligomers.

Abstract: Particulate polystyrene containing blowing agent and having improved expandability is based on polystyrene having a weight-average mean molecular weight of not more than from 130,000 to 180,000 and a molecular weight distribution curve in which the high molecular weight flank drops steeply. The expandable polystyrene particles are produced by polymerizing styrene in aqueous suspension in the presence of blowing agents and of chain transfer agents or styrene oligomers.

Abstract: The invention relates to pre-expanded plastic beads based on poly-para-methylstyrene with the following properties:(a) the bead size lies between 0.2 and 3 cm,(b) the thermal stability, measured in accordance with DIN 53,424 is above 110.degree. C., and(c) the bulk density is below 35 g/l.The corresponding expandable plastic beads are prepared through the polymerization of para-methylstyrene in an aqueous suspension with the addition of volatile organic blowing agents during or after polymerization, whereby polymerization occurs in the presence of molecular-weight-regulating substances. Typical molecular-weight-regulating substances are organic chain transfer agents with a transfer constant K between 0.1 and 50, said agents being added in amounts ranging from 0.1 percent by weight to 1 percent by weight when a yield ranging from 20 to 95 percent is reached. Oligomers of the styrene or para-methylstyrene in quantities from 0.1 percent by weight to 10 percent by weight may also be employed.

Abstract: Particulate expandable styrene polymers having short minimum molding times which are coated with from 0.005 to 0.5% by weight, based on the expandable styrene polymer, of a mono- and/or poly-urethane melting below 150.degree. C. and obtained by reaction ofI (a) aliphatic, cycloaliphatic, aliphatic-cycloaliphatic, araliphatic and aromatic mono- and/or poly-isocyanates with(b) linear or branched monoalcohols of from 2 to 24 carbon atoms which may or may not be olefinically unsaturated and/or halogenated, or mixtures of such monoalcohols and(c) optionally dihydric to tetrahydric alcohols,the ratio of NCO groups to the total number of hydroxyl groups being from 0.25 to approximately 1:1 and the molar ratio of dihydric to tetrahydric alcohols (if used) to polyisocyanates being not more than 0.

Abstract: Particulate expandable styrene polymers which contain from 0.0001 to 0.2% by weight, based on the styrene polymer, of an inhomogeneously distributed nucleating agent for expandable polystyrene, the nucleating agent being present only in a peripheral zone of the particles while the interior of the particles is free from nucleating agent. Nucleating agents which may be used are organic compounds having at least three bromine atoms, bonded to aliphatic or cycloaliphatic structures, in the molecule, or bromine compounds which are polymerizable, or are copolymerizable with styrene.

Abstract: Particulate expandable styrene polymers containing organic halogen compounds and, to improve processability, from 0.0001 to 1.0% by weight, based on the styrene polymer, of an amine which is soluble in styrene and free from hydroxyl groups.

Abstract: Particulate, expandable styrene polymers containing a flame-proofing organic halo compound as expanding agent and also a mixture of from 2.5 to 30% by weight of a hydrocarbon of from 3 to 6 carbon atoms and from 97.5 to 70% by weight of monofluorotrichloromethane, based on the total weight of said mixture serving as expanding agent, show good processability and exhibit self-extinguishing properties even during processing.