DIELECTRIC-RELAXATION, DIPOLE-MOMENT COMPONENTS AND ORDER PARAMETERS IN NEMATIC MIXTURES OF P-METHOXYBENZYLIDENE-P-N-BUTYL-ANILINE AND 4-N-HEPTYL-4'-CYANOBIPHENYL

The dielectric relaxation spectrum of mixtures of p-methoxybenzylidene -p-n-butylaniline (MBBA) and 4-n-heptyl-4'-cyanobiphenyl (7CB) are rep orted in samples aligned parallel and perpendicular to the applied mea suring held. Two dispersion processes are observed in the parallel ali gned samples and a single broad dispersion in the perpendicular aligne d samples. The experimental results show that the dielectric dispersio n is a co-operative process and there is no evidence (on the time scal e of the experiment) of the formation of any molecular complexing. The intensities are analysed to give give dipole-moment components parall el and perpendicular to the rotational axis of the :polar entity invol ved in the dispersion process as well as the nematic order parameters.