357-361.
The dielectric constants (real and imaginary) of benzaldazine and its hydroxy derivatives have been measured at different frequencies up to 100 kHz. The measurements were also carried out at different temperatures up to near the melting point of each sample. Two phase transitions were obtained during measurements at 320 and 370 K. The rotation of the benzene ring around the -CN- axis was responsible for these transitions. The effect of variation of the OH substituent between o-, p- and w-positions on the dielectric loss was discussed. The a.c. conductivities for the different samples were measured and explained. © 1992.