| 摘要 |
Cross-linked polymeric acrylonitrile soluble in solvents for polyacrylonitrile, e.g. ethylene carbonate and dimethyl formamide, acetamide and sulphoxide, comprises at least 85 mols. per cent of acrylonitrile and from 0-15 mols. per cent of another monoethylenically unsaturated monomer cross-linked by up to 0.06 mols. per cent of a cross-linking agent, the mols. per cent referring to the total number of structural monomeric units in the polymer. Monoethylenic monomers specified are acrylic and methacrylic acids and their esters, e.g. methyl acrylate, acrylamide, methacrylamide, methacrylonitrile, vinyl and vinylidene chlorides and vinyl acetate. The cross-linked polymeric material may be made by polymerizing in solution or aqueous emulsion a mixture of at least 85 mols. per cent of acrylonitrile with up to 15 mols. per cent of a monoethylenic monomer and from 0.001 to 0.3 mols. per cent of a polyethylenic cross linking agent, e.g. methylene-bis-acrylamide, divinyl benzene, triacrylohexahydrotriazine, diallyl phthalate, diallyl maleate and ethylene glycol diacrylate. In examples aqueous emulsion polymerization is carried out in the presence of sodium lauryl sulphate and a mixture of ammonium persulphate and sodium metabisulphite. Alternatively acid or amine groups may be copolymerized into the polymer which are then reacted with a polyhydric compound, a polyvalent metal compound or a polybasic acid, for example an acrylonitrile-acrylic acid copolymer may be reacted with glycol or aluminium or magnesium sulphate.
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