Research on crystal structure of wood cellulose

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We have predicted that lattice parameters and X-ray diffraction intensity of cellulose crystals vary due to the variety of its origins. To confirm the results obtained from previous study, cellulose samples from two sftwoods of akamatsu and karamatsu, and tow hardwoods of keyaki and redmeranti, which were thought to be the most important cellulose origin, were subjected to delignification and/or acid hydrolysis treatment and their structural modification was analysed. In adition, we refined the crystal structure of wood cellulose by the computer program of PS79, developed by A.sarko and P.Zugenmaier. Firstly, concerning the predicted variety of crystal structure of cellulose in relation to its origin, we have thoroughly investigate the effects of acid-hydrolysis, because any change caused to crystal structure with delignification treatment. The results obtained from acid hydrolysis by 2.4N boiling HCl aq. for 0 to 16hrs were followings.1. Samples without any treatment gave a clear diff … More erence in the monoclinic angle ; of softwood was 1.5 degree larger than that of hardwood. Since relative ratio of X-ray diffraction intensity R was smaller in the case of softwood and R smaller in hardwood, the structural difference of these two groups should result.2. Accompanying the progress of acid-hydrolysis, (1)while of softwood decreased about 1.1-1.4 degree, that of hardwood decreased 0.5 deg. or sometime increased 0.1 deg. Thus, the difference in was reduced. (2)Any change in fiber repeat was noticeable. (3)In both case, softwood and hardwood, R value decreased and R increased. The rate of decreasing and increasing value was not equal between two groups so that the difference in R and R value was minimized. These lives of investigation suggest that the predicted difference between softwood and hardwood is caused by amorphous cellulose and/or hemicellulose, which can be removed by hydrolysis.3. Regard to structural model of cellulose, the refinement analysis suggests that cellulose crystal prefer, (1)tg conformation of O6 position, (2) cellulose chains at the corner and the center of the unit cell rotate each other around their molecular axis about 43-45 degree in akamatsu, karamatsu and red meranti, and about 48-49 degree in keyaki. Longitudinal shift of these chains was about 2.4 A, being independent form the species. Less