DIELECTRIC-RELAXATION BEHAVIOR OF ABSORBED WATER ON AROMATIC POLYESTERS

This study was undertaken to elucidate the state and/or the motion of absorbed water and the effects of absorbed water on beta-processes of polyesters from the results of dielectric measurements. The difference spectra were obtained by subtracting the dielectric loss curves of the dry samples from those of the water-absorbed samples. The difference spectra show the following features: 1) the line shape of the difference spectra are symmetric and the same for the four samples, 2) the heights of the peak in the difference spectra depend on the amount of absorbed water, 3) there is little change in the height of these peaks with decrease of temperature. These facts suggest that the molecular motions of beta-processes in polyesters are independent of small amounts of absorbed water, though each observed beta-process is affected by absorbed water. The dipole moment of absorbed water was calculated from the dielectric increment of the difference spectra. The result shows that the water in the polyesters is absorbed in the gas phase.