リグニンの誘電特性

抄録

In order to make clear the mechanism of the dielectric relaxation processes in MWL (milled wood lignin), the dielectric loss factors of HINOKI MWL, acetylated HINOKI MWL and three kinds of DHP (dehydrogenation polymer) prepared from p-coumaryl alcohol, p-coumaric acid and isoeugenol, respectively, were measured over the frequency range of 3×10² to 1×10⁶Hz and the temperature range of -70°C to room temperature.
The results show that two relaxation processes exist in MWL: one is observed in high frequency range below room temperature and the other in low frequency range at room temperature. The activation energy for the relaxation process in high frequency range is about 10kcal/mole and this relaxation process is almost eliminated by acetylation. Furthermore, the same ralaxation process is observed in DHP from p-coumaryl alcohol in which CH₂OH group is present. From these results it is considered that the relaxation process in high frequency range is associated with the reorientation of CH₂OH dipoles. On the other hand, the activation energy for the relaxation process in low frequency range is about 14kcal/mole and the relaxation process is eliminated by drying and is not observed in acetylated MWL. Consequently, it is considered that the relaxation process in low frequency range is due to the reorientation of water molecules adsorbed to OH group.