Light‐scattering and viscosity measurements were obtained for seven fractions of the diethylacetamide derivative of cellulose xanthate (DAX) in 90% dimethyl sulfoxide. The degree of substitution (D.S.) range represented by the samples was 0.4 to 1.22; the molecular weight range was 112,000 to 446,000. The following empirical equation between the intrinsic viscosity and D.P.w was found: [η] = (5.63 – 3.35 D.S.) × 10−3 D.P.w. As reflected by the km– D.S. plot, the Martin constants, and the configuration parameters, it was apparent that the low D.S. derivatives are considerably more extended in solution than high D.S. derivatives of the same chain length. Under such conditions, it is apparent that solvent‐polymer interaction has assumed an important role in determining the polymer configuration. The behavior of the DAX molecule in solution was found to be strikingly similar to that of other cellulose derivatives. Hydrodynamic considerations revealed that the behavior in solution appears to approach that of the more flexible synthetic polymers at D.S. levels above 0.9 and molecular weights above 400,000.

Viscose‐grade cotton linters (DPw = 1135) were converted to viscose by the emulsion xanthation technique. Two variables—namely, substitution level and xanthation time—were considered insofar as their influence on the uniformity of substitution with regard to chain length was concerned. The stable diethylacetamide derivatives were prepared by reaction with diethylchloroacetamide and fractionally precipitated from aqueous 2‐chloroethanol. The DPw and degree of substitution (DS) of the individual fractions were determined. The results in each case indicated that the longer chains were more highly substituted than the shorter chains. For a constant xanthation time (6 hr.), uniformity in substitution improved with increasing substitution level. For a constant CS2:cellulose ratio (1.48), uniformity increased with xanthation time. A mechanism is suggested which accounts for these phenomena.