Some Physical Properties of Cellulose Derivatives Prepared by Homogeneous Periodate Oxidation

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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.