ABSTRACT:Cellulose triacetate(CTA, combined acetic acid content, 61.0wt%) was successfully fractionated on the basis of molecular weight by successive solutional fractionation using 1-chloro-2,3-epoxypropane as the solvent and hexane as the nonsolvent. The fractions cover a very wide range of molecular weights, having comparatively narrow molecular weight distribution (em). For CTA/DMAc system, the CTA chain is gaussian in the unperturbed state and a ( =dln =Flory's viscosity parameter)=0.106 and the draining parameter X =2 were obtained. On the basis of the light scattering and viscosity data, the short-range interaction parameter A=l.46x 10-8 cm, the conformation parameter cr=3.14, and the characteristic ratio Coc.=20.4. These values were estimated by using method 2B, 2C, and 2G, proposed in the previous paper (This journal, 10, 409 (1978)). The A value in polar solvents (group I: DMAc, trifluoroacetic acid, and acetone) is significantly larger than that in non-polar solvents (group II: dichloromethane, tetrachloroethane, and trichloromethane). The effect of the degree of substitution on [17] and cr for cellulose acetate in acetone is just the reverse of those for cellulose nitrate in the same solvent. The CTA chain is semiflexible and the contribution of the volume effect on [17] is much smaller than that of the draining effect.