Acetylation behaviour of cotton and bagasse celluloses. I. Effect of cold alkali refining

Abstract

AbstractSecondary cellulose acetates from untreated cotton linters, bagasse dissolving pulp and bagasse kraft pulp as well as the acetates from the same pulps after treatment with sodium hydroxide solutions of different concentrations at room temperature were prepared. The acetates obtained were chemically and physically evaluated. The acetate from the untreated linters showed the best chemical and physical properties. It was followed by the acetylated dissolving pulp and finally the acetylated kraft pulp. The cold alkali treatment of the three pulps increased the accessibility of the cellulose hydroxy groups to reactant molecules and improved the filtrability of the acetates obtained. The higher content of hemicellulose and low molecular weight carbohydrates in the pulp, the lower was the thermal stability of the acetate. Cellulose acetates from alkali treated linters, dissolving pulp and kraft pulp were of lower thermal stability than the acetates obtained from the untreated pulps. However, treatment of the dissolving pulp with 15% sodium hydroxide before acetylation dissolved the degradation products of the carbohydrates which were responsible for the decrease in heat stability.