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

Toward novel materials by carbonization of cellulosic raw materials

通过纤维素原料的碳化开发新型材料

基本信息

批准号：
11460077
负责人：
KUGA Shigenori
金额：
$ 10.05万
依托单位：
THE UNIVERSITY OF TOKYO
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

Basic features of pyrolysis of cellulose were reexamined in terms of loss of crystallinity and carbon yield. Cellulose crystallite was found to degrade at above 320C in inert atmosphere. Mass yield of resulting carbon was as low as 1/3-1/4 of theoritical value for pure cellulose. Imprivement of carbon yield was achieved by addition of small amounts of sulfuric acid to cellulose, the yield reaching about 80% of theoritical value. Derivatization of cellulose also had remarkable effect in increasing the yield, as observed for periodic acid-oxidized cellulose. Further derivatization of dialdehyde cellulose through reactions with amines caused anomalous explosive decomposition of the material at high level of derivatization.Highly crystalline cellulose samples from bacteria, tunicate or algae were graphitized at above 1600C, and crystallinity of the resultant material was in accord with that of starting material. The graphitized material contained microfibrillar crystallite apparently derived from the cellulose microfibril. This new form of graphite, carbon nanorod, may lead to novel applications. Hence efforts were made for preparing this material in higher yields, through processing of cellulose by freeze drying, embedding in other materials, and coating of microfibrils. Coating with silver showed some effect, but significant improvement in yield has not been achieved.As a polymer having cellulose-like structure, poly (vinyl alcohol) was examined for its pyrolytic carbonization with addition fo sulfuric acid. Unlike pure material, PVA with sulfuric acid showed weight loss at around 250C, giving loss levels that correspond to stoichiometric dehydration. The resulting material is considered to contain polyacetylene-like structure and may lead to a novel electroconductive polymer.

从结晶度损失和碳产率两个方面重新考察了纤维素热解的基本特征。在惰性气氛中，纤维素微晶在320 ℃以上发生降解。所得炭的质量产率仅为纯纤维素理论产率的1/3-1/4。在纤维素中加入少量硫酸可提高炭的产率，产率可达理论值的80%左右。纤维素的衍生化在增加产率方面也具有显著效果，如对于高碘酸氧化的纤维素所观察到的。将双醛纤维素与胺反应进一步衍生化，在高衍生化程度下引起材料的异常爆炸性分解，将细菌、被囊动物和藻类的高结晶纤维素样品在160 0 ℃以上石墨化，所得材料的结晶度与起始材料的结晶度雅阁。石墨化的材料含有微纤维状微晶，显然衍生自纤维素微纤维。这种新形式的石墨，碳纳米棒，可能会导致新的应用。因此，人们努力通过冷冻干燥处理纤维素、包埋在其他材料中以及涂覆微纤维来以更高的产率制备这种材料。涂银有一定效果，但产率没有明显提高。聚乙烯醇作为一种具有纤维素样结构的聚合物，在添加硫酸的情况下进行了热解碳化研究。与纯材料不同，具有硫酸的PVA在约250 ° C下显示出重量损失，给出对应于化学计量脱水的损失水平。所得材料被认为含有聚乙炔样结构，并可能导致一种新的聚乙炔聚合物。