Processing Lyotropic Crystalline Solutions of Cellulose in the Liquid Ammonia/Ammonium Thiocyanate Solvent System to Form High Performance Fibers and Films

纤维素具有形成纤维和薄膜的潜力，这些纤维和薄膜比目前已知的纤维和薄膜要坚固得多。建议通过对在氨/硫氰酸铵溶剂体系中形成的液晶溶液进行湿法纺丝来实现这一点。通过调节溶剂比和聚合物浓度，可以补偿手性纤维素分子形成胆甾型溶液的倾向，而形成向列型溶液。到目前为止的研究表明，向列型系统是形成高强度、高模数纤维的首选系统。在开发生产这类纤维的工艺时，必须仔细注意重要的纺丝参数和后挤压条件。纤维素是一种自然产生的材料，可用于工业，如树木的木浆或棉花植物的纤维。任何一种形式的纤维素都不会融化，也不容易在任何溶剂中溶解。为了制造有用的产品，如纤维或由纤维素制成的薄膜，人们必须能够通过加工熔体或溶液来成形它。此外，人们还发现，如果在溶剂中产生浓度非常高的溶液，可能会产生一种非常有趣的物质形式，称为液晶。如果用这些纤维素液晶制备纤维或薄膜，就可能形成非常坚固和耐用的新纤维、织物和薄膜。这种新的轻质、坚固、坚硬的材料或复合材料有可能在许多方面取代钢和其他传统的工程材料。

Cellulose has the potential for forming fibers and films that are much stronger than those which are currently known. It is proposed to accomplish this via wet spinning of liquid crystalline solutions that form in an ammonia/ammonium thiocyanate solvent system. The tendency for the chiral cellulose molecules to form cholesteric solutions can be compensated and nematic solutions formed in their stead by adjusting the solvent ratio and the polymer concentration. Research thus far indicates that a nematic system is the preferred one from which high strength, high modulus fibers will be formed. In developing a process for producing such fibers, careful attention must be given to both important spinning parameters and to post extrusion conditions. Cellulose is a naturally occurring material which is available to industry as wood pulp from trees or as fibers from cotton plants. Cellulose in either form does not melt nor does it dissolve readily in any solvent. In order to make a useful product, such as a fiber or a film from cellulose, one must be able to shape it by processing a melt or a solution. Further, it has been discovered that if very concentrated solutions are produced in a solvent, a very interesting form of matter called liquid crystals may develop. If fibers or films are prepared from these cellulose liquid crystals, new fibers, fabrics, and films may be formed which are exceptionally strong and resistant. It is possible that the new lightweight, strong, stiff materials or composites could replace steel and other conventional engineering materials in many uses.