Cellulose molecular weights determined by viscometry

The equation suggested in the standard method SCAN C15:62 for the estimation of the degree of polymerization (DP) of a cellulose sample from its intrinsic viscosity ([η]) in cupriethylenediamine hydroxide (cuene) solution, P 0.905 = 0.75 [η]/mL g −1 , where P is an indeterminate average DP, is incorrect. Although differences between the experimental results from several laboratories need to be resolved, a tentative replacement ( P V = 1.65 [η]) is suggested, based upon the pooled data and a conversion from the intrinsic viscosity of cellulose tricarbanilate (CTC) in tetrahydrofuran (THF) to that of cellulose in cuene. The treatment of statistical errors in Mark–Houwink–Sakurada parameters, and the nonlinearity of the log[η]−log P v correlation are discussed.