Study on Cellulosic Fiber Spun from its Lyotropic Mesophase Dope

Abstract

An attempt was made to elucidate the effect of the total degree of substitution («F») and its distribution («fk», k =2, 3 and 6) of cellulose acetates (CA) in their lyotropic solution in common solvent (dimethvlacetamide; DMAc) on their molecular orientation behavior characterized by IR analysis, and to compare the properties of cellulose diacetate fibers spun from lyotropic solutions differing solvent (DMAc and aq-70 wt% nitric acid (HNO3)). The followings are found : 1) Molecular orientation phenomena of polymer and solvent for CD/DMAc lyotropic systems on imposing shear significantly differ depending on both (F) and (fk), for example, CA with higher «f6»/«F») tends to show similar molecular orientation to cellulose II even at almost same low (F). 2) The fibers spun from CDA/aq.70 wt% HNO3 lyotropic system exhibit always superior mechanical properties such as tensile strength and Younds' modulus to those of the fibers spun from CDA/DMAc lyotropic system. 3) The former lyotropic system shows a characteristic IR perpendicular dichroism band corresponding to ring CO stretching band which ordinary shows parallel dichroism for cellulose. 4) Kevlar-like structure is expected for the fibers spun from CDA/aq. 70 wt% HNO3 lyotropic system.