Abstract: A process for the manufacture of so-called "cold" flexible polyurethane foams is described, which consists of pouring foaming compositions (obtained by mixing, in the main, very active polyether-polyols having an average of at least two hydroxyl groups per molecule, polyisocyanates, water, catalysts and crosslinking agents) into moulds, awaiting the formation of the foams and releasing these from the mould, the characteristic feature being that the composition contains 0.05% to 3% by weight, relative to the polyether-polyols, of a triorganosilylated polyol of the general formula (A).sub.a C(CH.sub.2 OSiR.sub.3).sub.4 -a, in which the symbols R, which may be identical or different, represent methyl, ethyl or vinyl radicals with the proviso that at least one radical R per SiR.sub.3 group is a methyl radical, the symbol A represents a methyl or ethyl radical and the symbol a represents 0 or 1. This process makes it possible to stabilize the foams and give them a regular cellular structure.

Abstract: Organopolysiloxane copolymers comprising units of the general formulae ##STR1## wherein R represents an alkyl group with 1 to 3 carbon atoms or a vinyl group, R' represents a divalent hydrocarbon radical with 1 to 10 carbon atoms, Q represents an organic radical of the formula --OG, ##STR2## or --OSiR.sub.3 in which G represents an alkyl radical with 1 to 4 carbon atoms, and each R group, which may be identical or different, is as defined above, n represents 2, 3 or 4, the C.sub.n H.sub.2n group being straight or branched and y represents a number from 4 to 60; the C.sub.n H.sub.2n groups being the same or different, the ratio of the number of (CH.sub.3).sub.2 RSiO.sub.0.5 units to the number of SiO.sub.2 units being 0.55:1 to 0.75:1 and the ratio of the number of ##STR3## units to the number of SiO.sub.2 units being 0.005:1 to 0.1:1 are used as stabilizers in the preparation of open-cell polyvinyl chloride foams. The raw foams can be easily shaped or moulded prior to gelling and gel without gain of density.

Abstract: Organopolysiloxane copolymers comprising units of the general formulae (CH.sub.3).sub.2 RSiO.sub.0.5 and ##EQU1## and SiO.sub.2, wherein R represents an alkyl group with 1 to 3 carbon atoms or a vinyl group, R' represents a divalent hydrocarbon radical with 1 to 10 carbon atoms, Q represents an organic radical of the formulae --OG, ##EQU2## or --OSiR.sub.3 in which G represents an alkyl radical with 1 to 4 carbon atoms, and each R group, which may be identical or different, is as defined above, n represents 2, 3 or 4, the C.sub.n H.sub.2n group being straight or branched and y represents a number from 4 to 60; the C.sub.n H.sub.2n groups being the same or different, the ratio of the number of (CH.sub.3).sub.2 RSiO.sub.0.5 units to the number of SiO.sub.2 units being 0.55:1 to 0.75:1 and the ratio of the number of ##EQU3## units to the number of SiO.sub.2 units being 0.005:1 to 0.1:1 are used as stabilizers in the preparation of open-cell polyvinyl chloride foams.