Study on Cellulosic Fiber Spun from its Lyotropic Mesophase Dope

Influence of the Distribution of Degree of Substitution in Cellulose Acetates on Lyotropic Dope properties and Some Typical Properties of Cellulose Diacetate Fibers Spun from Different Lyotropic Dopes

Abstract

An attempt was made to elucidate the effect of the total degree of substitution («F») and its distribution («f_k», 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 (f_k), 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.