Abstract: A method for improving the expandability of styrenic polymer particles is disclosed. The method comprises copolymerizing a styrenic monomer with an amount of an acrylate monomer effective to improve the expandability of the particles without adversely affecting their heat sensitivity. Polymer foams of low density can be prepared with reduced amounts of blowing agents.

Abstract: A waterstop splicing method and apparatus including a table having first and second coplanar aligned table top surfaces that simultaneously and equally, open and close by mechanical means driven by adjustable compression springs which provide equal forces to both tops. The table is equipped with two identical clamping arm assemblies in proximate relation to the facing edges of the two table surfaces, with one clamping arm assembly for each side, each of the clamping arm assemblies being provided with a bar having slidably and lockably assembled thereon a plurality of clamp devices, which are individually adjustable for pressure, width and cross-section of the waterstop strips for enabling securing of a waterstop to the table at any desired angle without puncturing. A removable recessed channel is provided in the middle of the table for supporting a thermoplastic welding iron having opposing heated parallel surfaces for simultaneously contacting the ends of a pair of aligned strips.

Abstract: Expandable styrene polymer particles are surface-coated with conjugated diene elastomers to prevent the particles from lumping together during expansion. The coating is applied by adding 0.05-0.25 part of conjugated diene elastomer to an aqueous suspension containing 100 parts of polymer particles during the impregnation of the mixture with a blowing agent.