Evaluating the quality and processability of cotton linter-derived cellulose acetate by characterization of native and artificial fines

Abstract Understanding the chemical characteristics and residual impurities of a dissolving pulp feedstock is necessary to enhance both the quality and processability of yielded cellulose acetates. Fiber fractionation was performed with three different cotton linter feedstocks. Biomass compositional analysis and fiber quality analysis were used to determine the carbohydrate content of the fractionated fibers and the quantity of fines. To evaluate the impact of fines on the acetylation of cotton linters, artificial fines were prepared from fractionated long fibers and added back to long fibers in varying fines content blends. The cotton linter pulps and artificial fines blends were used to generate acetates which were characterized via degree of substitution measurement by FTIR, the ensuing weight fraction of acetone insoluble substance, and the filtration rate of the acetate. A test to measure the amount of sulfuric acid insoluble substances (SIS) was developed to explain the formation of insoluble gel particles in acetate media; an R 2 of 0.97 was found between fines and resulting SIS. Then, SIS contents were correlated with the acetone insoluble substances in the acetates (R 2 = 0.98). Fines contents were found to be highly influential on the acetate’s degree of substitution, insoluble substance content, and filtration rate (R 2 = 0.99). Thorough activation and excess acetic anhydride reagent were found to limit the effects of fines on degree of substitution. Graphical abstract