A new model for cellulose microfibril

(1)纤维素微纤维的结构形态：纤维素链在胞内呈“平行向上”排列，其还原端与c轴重合。因此，纤维素链在非还原端合成。纤维素I β晶体有一定程度的扭曲，严格地说，它是不完美的晶体。纤维素α晶体的表面可能与α晶体的表面不同。天然纤维素的多晶化很可能来自于晶体形成阶段是否有应力。我们成功地制造了一种高度定向的纤维素微纤维薄膜。该膜的中子衍射揭示了氢在纤维素晶体中的可能位置。因此，纤维素II晶体是一种反平行填料，有利于分子的疏水表面。平行链式填料的β几丁质经HC1溶液溶胀转化为反平行的α几丁质，其过程与碱处理的纤维素I到II相似。(2)纤维素微原纤维的性质纤维素晶体的热膨胀为我们提供了一些新的认识。晶体仅向轴向膨胀。热分解的抵抗性取决于纤维素微纤维。我们可以估计出毒药的纤维素晶体比例。机械现象表明存在不稳定的结晶区。木材纵向杨氏模量表明，非结晶纤维素的取向和密度与结晶纤维素非常相似。在苎麻纤维的情况下，非结晶部分在两个方向上都存在。(3)纤维素微纤维对酶的敏感性：纤维素微纤维对酶的敏感性取决于其形态：典型的缬草晶体在其表面也有一些缺陷。纤维素微原纤维由于其起源而具有自己的形态。

(1) Structure and morphology of cellulose microfibril :Cellulose chain was found to be in the unit cell with "parallel up" packing, and its reducing end coincides with the c-axis. Consequently, cellulose chain is synthesized on the non-reducing ends. Cellulose I beta crystal distorts some extent and, strictly speaking, it is imperfect crystal. Surface of the cellulose I alpha crystal might be different from that of I beta. It is likely that polymorph of native cellulose comes from with or without stress in the forming stage of the crystal. We succeeded in making a highly oriented film of cellulose microfibril. Neutron diffraction of this film revealed probable position of hydrogen in the cellulose crystal. Consequently, cellulose II crystal is an anti-parallel packing which is favorable to hydrophobic surfaces of the molecule. Beta chitin with parallel chain packing transforms into alpha form of anti-parallel one through swelling by HC1 solution in the similar process of cellulose I to II by alkali treatment.(2) Properties of cellulose microfibrilThermal expansion of cellulose crystal gave several new knowledges. The crystal expands to only aaxis direction. Resistibility of thermal decomposition depends on cellulose microfibril. We can estimate Poison's ratio of the cellulose crystal. Mechanical phenomena suggest an unstable crystalline region. Young's modulus of wood in the longitudinal direction indicates that orientation and density of non-crystalline cellulose is very similar to those of crystalline one. In case of ramie fibers non-crystalline parts exist in the both directions.(3) Susceptibility of cellulose microfibril for enzyme :Susceptibility of cellulose microfibril for enzyme depends on its morphology : Typical crystal of valonia also has some defects on its surface.Cellulose microfibrils have their own morphology coming from their origin.