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方面重新审视了纤维素热解的基本特征。发现纤维素微晶在惰性气氛中在320℃以上时会降解。所得碳的质量产率低至纯纤维素理论值的1/3-1/4。通过向纤维素中添加少量硫酸实现碳收率的提高，收率达到理论值的80%左右。正如对高碘酸氧化纤维素所观察到的那样，纤维素的衍生化在提高产率方面也具有显着的效果。二醛纤维素通过与胺反应进一步衍生化，导致材料在高衍生化水平下发生异常爆炸性分解。来自细菌、被囊类或藻类的高结晶纤维素样品在1600℃以上进行石墨化，所得材料的结晶度与起始材料。石墨化材料含有显然源自纤维素微纤丝的微纤丝微晶。这种新型石墨——碳纳米棒可能会带来新的应用。因此，人们努力通过冷冻干燥加工纤维素、嵌入其他材料以及微纤维涂层来以更高的产率制备这种材料。银涂层显示出一些效果，但尚未实现产率的显着提高。作为具有类纤维素结构的聚合物，研究了聚(乙烯醇)在添加硫酸的情况下的热解碳化。与纯材料不同，含有硫酸的 PVA 在 250°C 左右表现出重量损失，损失水平与化学计量脱水相对应。所得材料被认为含有类聚乙炔结构，并可能产生新型导电聚合物。