Some Physical Properties of Cellulose Derivatives Prepared by Homogeneous Periodate Oxidation

采用新开发的均相高碘酸盐氧化法，首次制备了高断裂度的2，3-二醇纤维素（DAC），并得到了清晰透明的膜。DAC的粘弹性与纤维素的粘弹性进行了研究。在-150 ° C ~ 150 ° C温度范围内，110 Hz频率下动态力学测量表明，DAC有两种弛豫过程，分别集中在-70 ° C和112 ° C附近。第一个过程在-70 ° C时与介电弛豫有关，并且被认为与纤维素中的过程相似，这是由于羟甲基的运动。另一方面，在112 ℃左右，吡喃葡萄糖环的C_2-C_3键断裂导致该过程，而纤维素在类似区域没有类似的过程。这一过程被归结为主链上的微布朗运动沿着.根据应力-伸长率图的温度变化，DAC的玻璃化转变温度Tg估计为约80 ° C。高于Tg的DAC膜显示出在112 ℃下达到200%的显著伸长率。我们其次制备了在侧链中具有低聚氧亚甲基醚基团的新型二醇纤维素衍生物（di-OAc）。比较了二醋酸纤维素与具有相同侧链的纤维素衍生物（COAc）的动态力学性能。已知具有吡喃葡萄糖环的纤维素衍生物的特征在于在侧链中存在微布朗运动，其出现在与沿着主链的微布朗运动不同的区域中。然而，澄清的是，对于二-〇 Ac，主链和侧链微布朗运动同时发生。从这些结果，我们可以得出结论，这里获得的二醇纤维素衍生物在机械性能上与普通的具有吡喃葡萄糖环的纤维素衍生物有很大的不同。

In accordance with the newly developed homogeneous periodate oxidation procedure, we firstly prepared high cleavage level 2, 3- dialcohol cellulose(DAC)which gives off a clear and transparent film. Viscoelastic properties of DAC were investigated in relation to those of cellulose. Dynamic mechanical measurements for DAC at 110Hz over the temperature range from -150ﾟC to 150ﾟC revealed two kinds of relaxation processes, which were respectively centered around -70ﾟC and ll2ﾟC. The first process at -70ﾟC was related to dielectric relaxation, and was regarded to be, similar to the process in cellulose, due to the motion of methylol groups. On the other hand, the cleavage of C_2-C_3 bonds of the glucopyranose ring resulted in the process at around 112ﾟC, while no comparable process has been reported for cellulose in the similar region. This process was ascribed to the micro- Brownian motion along the main chain. From the temperature variation of the stress-elongation diagrams, the glass transition temperature Tg for DAC was estimated to be about 80ﾟC. The DAC film above Tg showed a marked elongation reaching 200% at 112ﾟC.We secondly prepared a, new dialcohol cellulose derivative(di-OAc)having oligo oxymeihylene ether groups in the side chain. Comparison of dynamic mechanical properties between di-OAc and the corresponding cellulose derivarive(COAc)with the same side chain as in di-OAc were made. Cellulose dirivatives with glucopyranose ring are known to be characterized by the presence of the micro Brownian motion in the side chain, which appears in the region different from the micro Brownian motion along the main chain. It was clarified, however, that for di-OAc the main chain and side chain micro- Brownian motion occur at the same time. From these results, we may conclude that the dialcohol cellulose derivative obtained here is quite different in the mechanical properties from ordinary cellulose derivatives having glucopyranose ring.