| 摘要 |
A fibre and film-forming composition comprises a solution in at least 75% sulphuric acid of a condensation polymer containing in the molecule repeating <FORM:1036471/C3/1> groups, the solution containing also an additive which is an amide having a molecular weight below 5000, such as N,N-dimethyl acetamide. The polymer may be a polyamide such as polyhexamethylene terephthalamide, a polyurethane or a polyurea. Particularly suitable polymers include polyamides melting above 275 DEG C. and having cyclic groups in the molecule, e.g. meta- or paraphenylene, cycloalkylene groups such as 1,4-cyclohexylene and/or heterocyclic groups such as piperazylene or an alkyl substituted piperazylene group, e.g. 2-methyl piperazylene or 2,5-dimethyl piperazylene, as an integral part of the polymer chain. A long list is given of condensation polymers which may be used. The amide additive may be a monomeric amide of a mono- or dicarboxylic acid containing up to 10 carbon atoms, in an N-monoalkyl or N,N-dialkyl derivative of such an amide, especially where the alkyl groups contain up to 4 carbon atoms. The solution may contain 5 to 30% by weight of the polymer and 1 to 15% preferably 2 to 8% by weight of the amide additive, based on the weight of the solvent.
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