Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/2/2011
Publication Date: 8/1/2011
Citation: Cheng, H.N., Dowd, M.K., Shogren, R.L., Biswas, A. 2011. Conversion of cotton byproducts to mixed cellulose esters. Carbohydrate Polymers. 86:1130-1136.
Interpretive Summary: This work continues our efforts to find new utilization for agricultural byproducts and waste. Two of the byproducts of the cotton process are cotton burr and cottonseed hull. These materials are currently used as mulch, feed roughage, or boiler fuel. Both materials are readily available and inexpensive, and value-added products from these materials are of some interest. In this work, we have developed a process to convert these cotton byproducts into higher alkyl and mixed cellulose esters. The process entails iodine-catalyzed esterification reaction which does not require strong inorganic acids or organic solvents like methylene chloride. It also obviates prior separation of cellulose from non-cellulosic components. Mixed cellulose esters such as cellulose acetate propionate (CAP) and cellulose acetate butyrate (CAB) are well known commercial products used as plastics, films, and coatings. The process may be of interest to scientists looking for alternative and cheaper sources of cellulose for the preparation of cellulose esters.
Technical Abstract: Cotton byproducts, such as cotton burr and cottonseed hull, can be used as low-cost feedstock for the production of specialty chemicals. The conversion of these cellulosic byproducts into mixed cellulose esters, e.g., cellulose acetate propionate (CAP) and cellulose acetate butyrate (CAB), was studied. Instead of using the conventional process for preparing these materials, which uses the appropriate anhydrides, sulfuric or perchloric acid, and methylene chloride as solvent, an iodine-catalyzed process was used that requires no chlorinated solvent in the reaction mixture. Product ester ratios and degrees of substitution were determined by 1H NMR spectroscopy. At the conditions studied, acetic anhydride was only slightly more reactive than propionic anhydride in the formation of CAP, but acetic anhydride was noticeably more reactive than butyric anhydride in the formation of CAB.