| 摘要 |
Filamentary materials consisting of polyacrylonitrile or copolymers or blends containing at least 70% of polyacrylonitrile and up to 30% of other polymerised mono-olefinic monomers, are placed in a closed chamber which is then evacuated and into which wet or saturated steam is introduced at a pressure within the range 30-60 p.s.i.g. and a temperature within the range 135 DEG -155 DEG C. until the pressure within the chamber is within the range 30-60 p.s.i.g., whereafter the chamber is immediately vented to the atmosphere. The above series of operations may be repeated one or more times. After one or more such series of operations the chamber may be finally evacuated to cool the materials and remove excess water therefrom. The filamentary materials may consist of a copolymer of 94% of acrylonitrile and 6% of vinyl acetate, or a blend of polyacrylonitrile and a polymer of an alkenyl-substituted N-heterocyclic compound. The filamentary materials may also consist of a 94/6 acrylonitrile/vinyl acetate copolymer blended with sufficient of a 50/50 acrylonitrile/vinyl pyridine copolymer to give a product containing 3%-8% by weight of polyvinylpyridine. A long list is given of other polymers which may be present in the filamentary materials in the form of blends or copolymers with polyacrylonitrile. In an example, staple fibres consisting of a 94/6 acrylonitrile/vinyl acetate copolymer blended with sufficient of a 50/50 acrylonitrile/2-methyl-5-vinylpyridine copolymer to give a product containing 6% by weight of pyridine polymer, and formed by wet spinning, are placed in an autoclave which is then evacuated and into which saturated steam at 40 p.s.i.g. is introduced until the pressure in the autoclave reaches 40 p.s.i.g. The introduction of steam is then immediately stopped and the autoclave is at once vented to the atmosphere. The above cycle is repeated 4 times except that the evacuation of the autoclave is eliminated between cycles. The staple fibres are then removed from the autoclave and dried. The process reduces the fibrillation to which wet spun polyacrylonitrile fibres are subject when in the form of yarns and fabrics and when subject to abrasion. Specification 735,208 is referred to.
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