抄録
The complex dielectric constants of solid phase N-methylacetamide are measured in the temperature range from -185°C to about 20°C at frequencies varying from 50 Hz to 3 MHz. The real part of the complex dielectric constant ε' of this material increases with temperature and decreases with frequency.
The temperature dependence of the imaginary part of the complex dielectric constant ε" is characterized by the following three regions at the various frequencies: (1) a peak appears at low temperature region (2) ε" increases gradually at higher temperature region below solid phase transition point Tc (9.3±0.4°C) and (3) ε" increases remarkably at Tc. The valley in the temperature dependence of ε" which divides the regions (1) and (2) tends to be indist-inguishable at low frequencies.
The dielectric anomaly observed at Tc is believed to be due to the rotational motion of the amino group. At this point the activation energy of the electrical conduction changes from 0.41 eV to 0.81 eV.
The relaxation time τ and activation energy ΔH are 1.33 × 10-5 sec and 21.1 kcal/mol, respectively, at -72°C.
