Gel-permeation chromatography of cellulose esters. Effect of average DP,DS, substituent size,and primary hydroxyl content

Hydrolyzed cellulose acetates and cellulose tripropionates prepared over wide ranges of intrinsic viscosity (DP) were fractionated by gel-permeation chromatography (GPC). An increase was observed in the polystyrene equivalent length (PSEL) at 50% cumulative height with increasing DP of the ester. Cellulose acetates and propionates over wide range of acyl content (DS), and a homologous series of triesters (propionate through heptanoate) of the same DP were fractionated by GPC. Increased amount and size of acyl gave relatively small increases in PSEL. The molecular size of cellulose acetates was not affected by the amount of primary hydroxyl present in the esters. The breadth of molecular weight distribution of the cellulose esters, as measured by the weight-average to number-average molecular size ratio, M?_w/M?_n, was not affected by any variation in the composition of the esters. A blend of cellulose tripropionates of widely differing DP gave a broadened GPC curve in agreement with that calculated from the components of the blend.