Degradation of wood pulp during acetylation

A comparison of the DP distributions of wood pulps and the cellulose acetates prepared from them shows that the DP distributions of the acetates are essentially exponential and virtually independent of the DP distribution of the original pulp. The DP of a number of acetates prepared under identical conditions from different pulps were unrelated to the DP to the starting pulps. Although the pulp DP is thus not a factor which determines the acetate DP, there are other intrinsic properties of the pulp which do affect the final DP of the cellulose acetate. The nature of these properties is not understood, but it can be shown that they are altered by changes in wood pulp processing. The ratio of hemicellulose in pulp to hemicellulose in the acetate made from it varies from one pulp to another. The acetate solution properties of the cellulose are more closely related to the composition of the acetate flake than to the composition of the original pulp. The viscosity of the concentrated acetate dope can be accounted for almost entirely in terms of flake DP and flake mannan content. Pulp manufacturers and acetate producers should strive toward conditions which increase the rate of degradation of the he mi celluloses and decrease the rate of cellulose degradation during acetylation.