<Original>Dielectric Properties of (Cellulose Oligo-Oxymethylene Ether) Acylates

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この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました。The dielectric properties of (cellulose oligo-oxymethylene ether) acylates were measured over a wide frequency and temperature range. The resulting complex dielectric constants (ε^*) were found to be closely related to complex dynamic modulus (E^*) in the region of the mechanical β and γ processes through the following expression: (ε^*-ε_U)l(ε_R-ε_U)=1-(E^*-E_R)l(E_U-E_R) where ε_R and ε_U are the relaxed and unrelaxed dielectric constant, while E_R and E_U are the relaxed and unrelaxed dynamic modulus. From this, we used the dielectric relaxation data for discussing the ft and y processes so far detected by mechanical experiment. In the dielectric measurement at constant temperatures, the γ absorption for the acetate exhibited a marked peak, while the ft absorption appeared as a low frequency shoulder to the γ peak. The normalized absorption curves for the f process in the acetate at temperatures between -70℃ and 0℃ reduced to a single curve (master curve). However, the absorption curves below -80℃ deviated from the master curve, but instead, they were on the master curve for the pivalate. In accord with this, the plots of (ε_R-ε_U) vs. temperature in the γ region for the acetate changed sharply at about -80℃. From these findings, the molecular relaxation mechanism for the f process in the acetate was considered to be different below and above ca. -80℃. The similar results were drawn for other COAs with linear side chain. It was also shown that the β process gave unexpectedly large values of the activation entropy (100eu or more), and the process was confirmed to be due to the micro-Brownian motion of the side chain.
京都大学の論文
1986-12-28

<Original>Dielectric Properties of (Cellulose Oligo-Oxymethylene Ether) Acylates

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