Abstract: The invention relates to expanded polypropylene beads having a density of from 5 to 200 g/l and a bead diameter of from 1 to 10 mm which comprise from 0.002 to 20% by weight of graphite particles.

Abstract: In a process for preparing expanded or expandable polymer beads based on biodegradable saturated polyesters made from at least one diol and from at least one dicarboxylic acid, A. polymer pellets are dispersed in a liquid, B. a volatile blowing agent is injected into the dispersion and made to impregnate the pellets at an elevated temperature, C. the pressure on the dispersion is reduced at an elevated temperature, whereupon the pellets comprising blowing agent expand to give foam, and, respectively, D. the pellets are isolated from the liquid.

Abstract: A process comprises producing expanded polyolefin particles by impregnating polyolefin granules with a volatile blowing agent in suspension under pressure, and then releasing the pressure. The suspension medium has a lower density than the polyolefin granules and the suspension is practically free from suspension agents.

Abstract: The invention relates to sound-absorbent foam moldings which have a sound-absorption level according to DIN 52215 of from 30 to 95% in the frequency range from 0.5 to 4 kHz. The foam is an incompletely fused molded polyolefin or polystyrene foam with from 10 to 40% interstitial volume.

Abstract: Expanded polyolefin particles are produced by impregnation of polyolefin granules with a volatile blowing agent in suspension under pressure and subsequent decompression. The blowing agent used is ammonia.

Abstract: In a process for producing polyolefin foam particles, partially foamed particles are produced in a first stage by extrusion of a polyolefin containing solid blowing agents, and these are then further foamed in the second stage using steam.

Abstract: Prefoamed polyolefin beads, produced by extrusion followed by granulation, have a crystal structure with a double peak.

Abstract: The invention relates to a process for the production of expanded polyolefin beads by impregnating polyolefin particles with volatile blowing agents in a fluidized bed.

Abstract: Polyolefin foams having a density of from 0.01 to 0.1 g/cm.sup.3 and having 2 to 1000 cells/mm.sup.2 and containing a resin acid, a lower alkyl ester of a resin acid or (hydro) abietyl phthalate as organic foaming aid have a homogeneous cell structure.

Abstract: Polyolefin foams having a density of from 0.01 to 0.1 g/cm.sup.3 and having 2 to 1000 cells/mm.sup.2 and containing a resin acid, a lower alkyl ester or a resin acid or (hydro) abietyl phthalate as organic foaming aid have a homogeneous cell structure.

Abstract: In foams having a density of from 0.01 to 0.2 g/cm.sup.3 and a cell count of from 2 to 1,000 cells/mm.sup.2 and based on an impact copolymer, the impact copolymer consists ofa) from 1 to 55% by weight of a block copolymer ofa.sub.1) from 35 to 65% by weight of ethylene anda.sub.2) from 35 to 65% by weight of propylene andb) from 45 to 99% by weight of a random copolymer ofb.sub.1) from 0.5 to 6% by weight of ethylene and from 94 to 99.5% by weight of propylene, or ofb.sub.2) from 0.5 to 12% by weight of but-1-ene and 88 to 99.5% by weight of propylene.

Abstract: Novel foams having a density of from 0.01 to 0.1 g/cm.sup.3, based on a copolymer comprising ethylene, propylene and a C.sub.4 - to C.sub.8 -.alpha.-olefin, and having a torsion modulus of from 100 to 800 N/mm.sup.2 have high tensile, compressive and flexural strengths and at the same time high elongation at break.

Abstract: Foam particles of propylene polymers which have shrunk from 40 to 95% of their original volume and have a bulk density of from 10 to 30 g/1 can be expanded if they are treated with air or nitrogen under superatmospheric pressure, subsequently decompressed. If desired post-foamed by heating and, after aging, re-treated with air or nitrogen under superatmospheric pressure, subsequently decompressed and aged under atmospheric pressure until the pressure in the cells has dissipated.

Abstract: Expandable styrene polymers and styrene polymer foams having a particularly uniform and fine-cell foam structure contain, as a cell regulator, small amounts of a mixture of resin acids, lower alkyl esters of resin acids or (hydro)abietyl phthalate and a polyoxyethylene monoester or monoether.

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 styrene polymers which contain a blowing agent and are surface-coated with from 0.05 to 1% by weight of an ester. The coating agent is a hydroxycarboxylic acid ester, or an ester of a carboxylic acid with an oxyalkylated alcohol; tristearyl citrate is a preferred ester.The styrene polymers can be used to produce foam moldings, with short mold dwell times and good welding of the foam particles.