Structure and Relaxation of Cellulose Derivatives

本研究的目的是获得具有高压电常数的新型纤维素衍生物，并研究其弹性、介电和压电弛豫。研究了氰乙基纤维素的压电性能。合成了新的含氟纤维素衍生物。研究了它们的压电性。纤维素衍生物的结晶度和取向都很低。因此，与氰乙基纤维素相比，它们的压电常数非常低，约为10^<-13> C/N。但由于纤维素衍生物的高取向性和结晶性，可以认为纤维素衍生物具有开发高压电材料的可能性。研究了纤维素衍生物的弛豫行为。研究了纤维素衍生物中由于侧链引起的分散，包括醋酸纤维素、甲磺酸纤维素、氰乙基纤维素、pdaf -氰乙基纤维素和pdaf -乙基纤维素。三乙酸纤维素和二乙酸纤维素侧链的局部模式存在差异。由于乙酰基的存在，三乙酸纤维素的压电、介电和弹性温度分散在-30ºC左右，甲基基的存在使二乙酸纤维素的压电、介电和弹性温度分散在-80ºC左右。在乙基纤维素和醋酸纤维素中观察到压电模量、介电模量和弹性模量的初始分散，在乙基纤维素中约为55‰，在三乙酸纤维素中约为100‰，在二乙酸纤维素中约为100‰以上。由于纤维素衍生物的结晶度和取向度都很低，我们无法测量它们的温度依赖性。测定了纤维素晶体的温度依赖性。在200℃以上，纤维素晶体发生垂直于分子链的急剧热膨胀。可以认为，纤维素晶体中存在温度分散。

The purpose of this research is to obtain new cellulose derivatives with high piezoelectric constants and investigate the elastic, dielectric and piezoelectric relaxations. The piezoelectric properties of cyanoethyl cellulose have been investigated. New cellulose derivatives with fluorine were synthesized. The piezoelectricity of them was investigated. The degree of crystallinity and orientation of the cellulose derivatives were very low. And so the piezoelectric constants of them were very low compared with that of cyanoethyl cellulose which was of the order of 10^<-13> C/N. But it may be considered that there is a possibility of development of high piezoelectric materials from cellulose derivatives by high orientation and crystallization of them. The relaxation behaviors of cellulose derivatives are investigated. Dispersions due to side chain in cellulose derivatives are studied about cellulose acetate, cellulose tosylate, cyanoethyl cellulose, PDAF-cyanoethyl cellulose, and PDAF-ethyl cellulose. There was a difference between cellulose triacetate and cellulose diacetate in local mode of side chain. There was observed the piezoelectric, dielectric and elastic temperature dispersions at about -30ﾟC in cellulose triacetate due to acetyl group, and at about -80ﾟC in cellulose diacetate due to methylol group. There were observed the primary dispersions of the piezoelectric, dielectric and elastic moduli in ethyl cellulose and cellulose acetate, at about 55ﾟC in ethyl cellulose, at about 100ﾟC in cellulose triacetate, and above 100ﾟC in cellulose diacetate. Because the cellulose derivatives were very low at the degree of crystallinity and orientation, we could not measure the temperature dependency of them. The temperature dependency of cellulose crystals was measured. There was an abrupt thermal expansion perpendicular to molecular chain in cellulose crystals above 200ﾟC. It may be considered that there is the temperature dispersion in cellulose crystals.