Synthesis of cellulose acetate from cotton byproducts

Cotton burr and cottonseed hull are relatively inexpensive cotton byproducts. In an effort to derive greater value out of these natural renewable materials, we have succeeded in converting part of them into cellulose acetate without prior chemical breakdown or physical separation of cellulose, lignin, protein, and other components. The conventional approach of treating the raw materials with acetic acid, acetic anhydride, and sulfuric acid in a solvent yielded very little product. An alternative process that involved treating the materials with acetic anhydride and iodine proved to be more successful. No solvent was used in this alternative approach except during the sample workup. The process was optimized by varying the temperature and the amounts of acetic anhydride and iodine used. The best yields obtained thus far were about 15–24%, which corresponded to conversion of between 50% and 80% of the starting cellulose. Formation of the acetates and the degree of substitution were monitored via NMR spectroscopy.