权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Structural analysis of native cellulose and its derivatives by direct imaging of molecular chains

通过分子链直接成像对天然纤维素及其衍生物进行结构分析

基本信息

批准号：
63440013
负责人：
OKANO Takeshi
金额：
$ 19.01万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1991
项目状态：
已结题

项目摘要

Following results were generated during 4 years of intensive research.1) 2 types of native celluloses categorized by ^<13>C-NMR, namely the Bacterial-Valonia type and the Cotton-Ramie type, were investigated by electron diffraction. They were assigned to the mixtwe of triclinic and monoclinc phases and the single phase of monoclinic, respectively. 2) The triclinic unit contained only one chain in it. Accordingly all the chains in one microfibril had the same polifity. The entirely new model were thereby proposed, which was a good alternative of 8-chain unit cell by Honjo-Watanbe. 3) Among woody celluloses such as those from softwoods, hardwoods, and bamboos, we have pointed out the difference in their diffraction intensities and dspacing data. The discriminant analyses based on those data showed that the holocelluloses of woody samples (17 softwoods and 61 hardwoods) were all categafift to the Cotton-Ramie type, although some of them (15 softwoods and 7 hardwoods) were once classified to the Bacterial-Valowa type before purification. There still remains, however, certain differences between softwoods and hardwoods. 4) Mercerization of cellulose, the transformation of cellulose I into II, is known to be an irreversible process. Having investigated intermediate crystalline alkaline celluloses in the early stage of swelling, we concluded that the fully swollen cellulose cannot go back to cellulose I. 5) Mercerization of dispersed microcrystalline cellulose was investigated by electron microscopy and x-ray diffraction. The change of crystalline state accompanied remarkable morphological changes such as the formation of cracks along microfibrils and the formation of bead-like particles. 6) The diamagnetic orientation behavior of the aqueous suspension of cellulose microcrystals was investigated When the strong magnetic field was applied, the crystals oriented perfectly, being their fiber axes perpendicular to the magnetic field.

经过4年的深入研究，获得了以下结果：1）通过电子衍射研究了2种天然纤维素<13>，即细菌-Valonia型和棉-苎麻型，这2种天然纤维素通过1H C-NMR分类。它们分别归属于三斜和单斜相的混合相和单斜相的单相。2)三斜单元中只有一条链，因此一根微纤维中的所有链具有相同的极性。由此提出了一个全新的模型，它是Honjo-Watanbe的8链晶胞的一个很好的替代。3)指出了软木、硬木和竹子等木质纤维素在衍射强度和间距数据上的差异。判别分析结果表明，尽管部分木材（15种软木和7种硬木）在纯化前曾被归为Bacterial-Valowa型，但木材样品（17种软木和61种硬木）的全纤维素均属于棉-麻型。然而，软木和硬木之间仍然存在某些差异。4)纤维素的丝光，即纤维素I转化为纤维素II，是一个不可逆的过程。通过研究中间结晶碱性纤维素在溶胀早期的情况，我们得出结论：完全溶胀的纤维素不能再回到纤维素I。5)用电子显微镜和x-射线衍射研究了分散微晶纤维素的丝光处理。结晶状态的变化伴随着显着的形态变化，如形成裂缝沿着微纤维和珠状颗粒的形成。6)研究了纤维素微晶体水悬浮液的抗磁取向行为。在强磁场作用下，纤维素微晶体完全取向，纤维轴垂直于磁场。