| 摘要 |
The process of the parent Specification (wherein shaped structures of certain elastomeric linear polymers are subjected to heat treatment above 80 DEG C. but below their melting point and then cooled) is modified in that undrawn shaped articles comprising the same or another substantially linear segmented elastomeric polymer are heated, while substantially free of applied stretch, at 105 DEG to 150 DEG C., preferably 110 DEG to 130 DEG C., for at least 5 minutes and preferably not more than 10 hours. "Undrawn shaped articles" are defined as filaments and like products which have not been stretched beyond the elastic limit subsequent to their formation, although they may have been drawn to some extent during the actual spinning operation, before they are fully set. "Segmented elastomers" are defined as elastomeric polymers comprising segments of a crystalline polymer having a melting point above 200 DEG C. alternating with segments of an amorphous polymer having a molecular weight above 600 and a melting point below 50 DEG C. The crystalline polymer may be a polyurea, polyurethane, polyamide, polybisureylene or polyester. The amorphous polymer may be a polyester, a polyether or a polyhydrocarbon. The crystalline segments generally make up about 10-40% by weight of the segmented elastomer, which generally has a molecular weight of at least 5,000. The preferred elastomers contain bis-ureylene segments alternating with polyether or polyester segments. In an example, samples of filaments formed by wet spinning a solution in dimethyl formamide of a diisocyanate-modified poly(tetramethylene oxide) glycol extended with hydrazine into water at 70 DEG C. are heated in an oven at 120 DEG C. without tension for periods ranging from 1/4 to 70 hours. The heat treatment improves the tenacity, stress decay and tensile recovery properties of the products. Specification 849,154 and U.S.A. Specifications 2,813,775, 2,813,776 and 2,965,437 also are referred to.
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