Research on crystal structure of wood cellulose

我们预测纤维素晶体的晶格参数和x射线衍射强度会因其来源的不同而变化。为了证实之前的研究结果，我们对赤松和卡拉松两种木材和两种被认为是最重要的纤维素来源的松木和红木的纤维素样品进行了脱木质素和/或酸水解处理，并分析了它们的结构改性。此外，我们还利用A.sarko和p.s zugenmaier开发的PS79计算机程序对木质纤维素的晶体结构进行了细化。首先，关于纤维素晶体结构的预测变化及其来源，我们已经彻底研究了酸水解的影响，因为任何晶体结构的变化都是由脱木质素处理引起的。用2.4N沸水盐酸水解0 ~ 16h得到的结果如下：未经处理的样品在单斜角度上有明显的差异；软木比硬木大1.5度。由于软木的x射线衍射强度R的相对比值较小，硬木的R较小，因此这两类木材的结构存在差异。随着酸水解的进行，(1)软木的酸水解度降低1.1 ~ 1.4度，硬木的酸水解度降低0.5度，有时升高0.1度，两者之间的差异减小。(2)纤维重复变化明显。(3)软、硬木两种木材R值均减小，R值均增大。两组间减小和增大的速率不相等，使R和R值的差异最小化。这些寿命的研究表明，软木和硬木之间的预测差异是由无定形纤维素和/或半纤维素引起的，它们可以通过水解去除。在纤维素的结构模型方面，精细化分析表明纤维素晶体倾向于(1)O6位置的tg构象；(2)赤松、karamatsu和red meranti的纤维素链和纤维素链围绕分子轴相互旋转约43-45度，keyaki的纤维素链约48-49度。这些链的纵向位移约为2.4 A，与物种无关。少

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