Studies on behavior for dissolution of native cellulose used bacterial cellulose in aqueous NaOH solutions

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In this study, we examined the possibility of dissolution of native cellulose used bacterial cellulose in aqueous NaOH solutions, and to obtain information about the morphology-relating dissolution: Bacterial cellulose was chosen because its cellulose is a superfine fiber and the biosynthetic process to fibril is relatively well known. The dissolution of bacterial cellulose in aqueous NaOH solutions has been investigated by the following three methods. First, the heat-treatment of bacterial cellulose was examined at high temperature above 180°C in aqueous NaOH solutions. As a result, the dissolution of bacterial cellulose was not observed. Because it is thought that decomposition by hydrolysis proceed more rapidly than dissolution. However, it became apparent that the decomposition of the cellulose at high temperature is not controlled by aqueous NaOH solution but by aqueous Na_2SiO_3 solution. Secondly, it is not yet known how intra-and inter-molecular hydrogen bonding and the disorde … More red component are produced during the crystallization, but these structure entities are very important in relation to solubility of native cellulose. In order to obtain new information about these structures, solid-phase nitration of bacterial cellulose has been investigated in detail. It is found that the disordered component is distributed in the whole areas of the fiber, and the diffusion of the reaction medium with high acid concentration breaks intra-and inter-molecular hydrogen bonding. In order to break only this hydrogen bonding, bacterial cellulose was treated at -80°C in the reaction medium with high acid. Such treated cellulose dissolved in aqueous NaOH solution. Thirdly, the treatment of hydrolysis of bacterial cellulose was carried out by sulfuric acid to discuss the relationship between solubility and polymerization degree of cellulose. This bacterial cellulose with low polymerization degree rapidly dissolved in 8% NaOH solution at low temperature. The detailed analysis for the relationship between solubility and polymerization degree of cellulose is in progress at present. Less