Polymer dope composition, composite fibers made therefrom and process

Abstract

There is provided a shaping composite dope composition comprising a cellulose derivative, an acrylonitrile polymer and a solvent capable of substantially dissolving these polymeric materials simultaneously therein, and exhibiting flow birefringence or optical anisotropy. A composite fiber made from the dope has a strucute such that the cellulose derivative is present in the form of a dispersed phase of fine fibers in a matrix of the acrylonitrile polymer, the crystalline orientation angle of the acrylonitrile polymer phase is 18.degree. to 63.degree. as measured by wide angle X-ray diffractiometry, and the ratio of the crystalline orientation angle of the cellulose derivative phase to the crystalline orientation angle of the acrylonitrile polymer phase satisfies a specified requirement. The composite fiber is excellent in the thermal dimensional stability and mechanical properties, such as tensile strength and tensile elongation and loop strength and loop elongation.