| 摘要 |
977,943. Polyacrylonitrile filaments. MONSANTO CO. Jan. 2, 1961 [Jan. 4, 1960], No. 85/61. Addition to 888,342. Drawings to Specification. Heading B5B. A molecularly orientated, normally lustrous polyacrylonitrile filament which is substantially free from porosity has an apparent density of at least 0.7 gm/cc., an area ratio of 1.5-1.1, an internal fibre surface area in the range of 150- 500 sq. m/gm., and collapsed sub-microscopic interstitial spaces spaced apart a distance of up to 300 A and having a frequency of 200-2,000 x 10<SP>14</SP> per gm. of filament, the said measurements being made before the orientation of the filament and the collapsing of said spaces. The filament may be formed by extruding a solution of polyacrylonitrile in N,N-dimethyl formamide or acetamide into a coagulating bath of polyalkylene glycol and then into a stretching bath of hot water. The filament may then be relaxed under low tension in a hot liquid or gaseous atmosphere and dried. Stretching may also occur in the coagulating bath which may contain up to 20% of solvent and up to 10% of water. |
