Verfahren zur Herstellung von Polyacrylnitril-loesungen

Acrylonitrile, if desired with at least one other copolymerizable monomer, e.g. methyl acrylate, styrene, itaconic acid, methallyl sulphonic acid, vinyl acetate and vinyl piperidine, is polymerized in solution in a liquid which is a solvent for the monomer and for the polymer and which contains a major proportion of dimethyl sulphoxide, in the presence of a free-radical initiator, e.g. an azo compound, and a reducing agent which is inert to the ingredients which form the mixture to be polymerized, e.g. thiourea dioxide, hydrazoisobutyric acid, ascorbic acid, d-xyloascorbic acid, erythroascorbic acid and araboascorbic acid, and salts thereof. The dimethyl sulphoxide solvent may contain minor proportions of water, acetone, methylene chloride and inorganic salts, e.g. calcium chloride, which last is stated to increase the rate of polymerization from the resulting polymer solutions fibres may be spun which are less discoloured than fibres spun from a polymer prepared in the absence of a reducing agent.