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.

根据结晶度和碳产量的丧失，对纤维素热解的基本特征进行了重新检查。在惰性气氛中，发现纤维素结晶石在320c以上降解。纯纤维素的理论价值的质量产量低至理论上值的1/3-1/4。通过将少量的硫酸添加到纤维素中，可以实现碳产量的振动，该产量达到了理论上的80％。纤维素的衍生化对增加产量也具有显着影响，如周期性酸氧化纤维素所观察到的那样。通过与胺的反应进一步衍生了氧化纤维素，导致材料在高衍生化的高水平上的异常爆炸性分解。从细菌，皮膜或藻类的高度结晶纤维素样品在1600C上进行了石墨，并在1600C上进行了石墨，并且所产生材料的结晶度与起始材料相符。石墨化的材料包含微纤维晶体，显然是源自纤维素微纤维的。这种新形式的石墨纳米棒可能会导致新的应用。因此，通过冷冻干燥，嵌入其他材料和微纤维涂层来处理纤维素，以更高的收率制备这种材料。用银涂层显示出一定的作用，但尚未实现显着提高。当具有纤维素样结构的聚合物时，检查了与添加的FO硫酸的聚合物（乙烯基醇）的热解碳化。与纯材料不同，含硫酸的PVA在250°C左右显示体重减轻，给出了与化学计量脱水相对应的损耗水平。所得材料被认为包含聚乙炔样结构，并可能导致新型的电导性聚合物。