Effect of pre-treatment of sugarcane bagasse on the cellulose solution and application for the cellulose hydrogel films

Abstract

Sugarcane bagasse was used as a cellulose resource, and the transparent cellulose hydrogel films were obtained from the purified cellulose by phase inversion process without chemical cross-linking, when the dissolved cellulose in lithium chloride/N,N-dimethyl acetamide was transformed into the solid film. On these processes, bagasse was pre-treated by 10 wt% sodium hydroxide in the absence and presence of bleaching of 10 vol% sodium hypochlorite (NaOCl) solution in order to obtain cellulose fibers. Here, the bleaching temperature was varied from 40 to 50°C. The effect of pre-treatment conditions on the resultant cellulose solution and hydrogel films was investigated. It was seen that strong bleaching removed most of lignin component from the bagasse. However, viscosity and size exclusion chromatogram of the cellulose indicated that this operation decreased average molecular weight of the cellulose fibers from 2.1 × 106 to 4.8 × 105. These property changes of fibers also caused increase of water content and weakening of mechanical strength of the resultant hydrogels. In addition, scanning probe microscopy in wet state revealed that the porous fiber network structure in the hydrogel was greatly influenced by bleaching with NaOCl. The average pore size of fiber network was decreased from 8.1 to 5.9 nm as the NaOCl treatment was at 50°C, because of expanded fibers in the swollen hydrogel. Copyright © 2016 John Wiley & Sons, Ltd.