| 摘要 |
Acetonitrile-soluble terpolymers having a specific viscosity between 0.1 and 0.6 comprise between 60 and 75 per cent of acrylonitrile, 10 and 30 per cent of vinyl chloride and 5 and 20 per cent of vinylidene chloride, the sum of the copolymerized monomers being 100 per cent, and the ratio of vinyl to vinylidene chloride in the terpolymer being from 0.5 : 1 to 5.0 : 1. Polymerization is carried out in aqueous media containing emulsifiers such as sodium dioctylsulphosuccinate and the sodium sulphate derivative of 7-ethyl-2-methyl undecanol-4, and catalysts such as benzoyl peroxide, potassium persulphate and mixtures of the latter with sodium bisulphite. Also present during polymerization may be mercaptans such as tert.-dodecyl mercaptan or mixed tertiary mercaptans of 8, 10 and 12 carbon olefins. A constant ratio of monomers is preferably maintained in the reaction mixture during polymerization by the addition of the monomers as required. The terpolymers are also soluble in dimethylformamide, dimethylacetamide and ethylene carbonate. The acetonitrile solutions may have incorporated therein stabilizers such as dibutyl tin maleate, dioctyl tin maleate, di-(2-ethylhexyl) tin maleate and the diglycidyl ether of diphenylol propane. Acetonitrile solutions of the terpolymers are wet spun into an aqueous coagulating bath which may contain up to 40 per cent of acetonitrile, the fibres produced are stretched at a temperature of at least 110 DEG C. and then subjected to a brief heat treatment at temperatures of 150 DEG C. to 250 DEG C. while under tension permitting controlled shrinkage.
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