Abstract: The invention relates to a method for forming an article comprising closed-cell microfoam from thermoplastic, wherein at least one molten thermoplastic comprising a foaming agent is subjected under pressure to a forming operation and, after the pressure has been at least partially released is cooled, wherein the amount of foaming agent is substantially identical to the amount corresponding to that quantity of gas released by the foaming agent which is comprised by a close-packed structure of the foam cells having a specific foam-cell diameter, substantially uniform throughout the foam, at the pressure prevailing during cool-down.

Abstract: Semipermeable membrane consisting of a polymer, embodying [--SO.sub.3 --] groups; said [--SO.sub.3 --] groups may be present in the continuous polymer chains or may be present in links between continuous polymer chains. The membrane may have been formed either by in situ coagulation of a polymer solution in the pores of a porous substrate or by interfacial crosslinking of a water-soluble phenolic polymer with a sulphonyl halide compound to form an [--SO.sub.3 --] groups embodying polymer in the pores of a substrate.

Abstract: A composition of polyvinylchloride containing the usual additives and a plate out preventing, chemically or physically acting drying agent. The drying agent is preferably an expanded and finely ground aluminiumsilicate, having a high oil absorption and water absorption and preferably low amounts of earth alkaline metals. The plate out preventing drying agent is incorporated in a normal additive composition in order to avoid handling of voluminous masses of drying agent. This incorporation is executed by mixing with a mixture of additives or during the chemical reaction for preparing the additive composition.