| 摘要 |
1278677 Treating polyacrylonitrile fibres CELANESE CORP 5 Aug 1969 [5 Aug 1968] 39108/69 Heading B5B [Also in Division C1] Polyacrylonitrile filamentary material is thermally stabilized by heating it in an oxygencontaining atmosphere at from 10‹ to 100‹ C. below its critical temperature, i.e. the highest temperature which the filamentary starting material can withstand for three minutes without loss of filamentary configuration, until the material contains at least 5% by weight of combined oxygen, thereafter further heating the material in an oxygen-containing atmosphere at a temperature between said critical temperature and a temperature 50‹ C. higher and continuing this further heating for at least one minute and until the material has an increased combined oxygen content of at least 7% by weight, to produce a thermally stabilized product which does not burn in a match flame, is capable of undergoing carbonization and still has a filamentary configuration. The filamentary material may be made from an acrylonitrile homo-polymer or a copolymer containing at least 99 mole per cent of acrylonitrile units and up to 1 mole per cent of monoethylenically unsaturated comonomer units. The filamentary starting material may have a single filament tenacity of at least 5 grams per denier. It may be a yarn having from 0À1 to 1À0 turns of twist per inch. The filamentary material may contain at least 95 mole per cent of acrylonitrile units may be able to withstand a temperature of at least 300‹ C. without loss of its filamentary configuration and may be passed continuously through one or more zones in which the thermal stabilization is effected. Orientation by stretching may be effected prior to thermal stabilization. The thermal stabilization may be effected under conditions which permit the filamentary material to shrink by from 10 to 30% of its original length. The thermal stabilization may be effected by heating in an oxygen-containing atmosphere first at from 10‹ to 40‹ C. below the critical temperature of the starting material and subsequently at up to 30‹ C. above the said critical temperature. The thermally stabilized material may be heated at a temperature of from 900‹ to 3000‹ C. in an inert atmosphere until a carbonized product is formed, especially at a temperature of from 2000‹ to 3000‹ C. in an inert atmosphere until substantially complete graphitization has occurred.
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