PHASE-TRANSITION BEHAVIOR OF BINARY-SYSTEMS - VARIOUS NON-NEMATIC SOLUTES IN NEMATIC SOLVENT (EBBA)

Phase transition behavior of the systems of EBBA with methyl alcohol (MeOH), 1,2-dibromoethylene (DBE), o-xylene, m-xylene, and p-xylene was studied determining the phase diagrams for each system by polarizing microscope. The slopes, beta //n and beta //i, of the nematic and the isotropic phase boundary lines in each system were qualitatively described by the molecular field treatment proposed by Humphries. The order parameters for both cis- and trans-DBE in EBBA were obtained from analyses of **1H-NMR spectra. In the nematic phase, they decrease with increase in temperature. In the nematic/isotropic coexisting phase (N/I phase), the order parameter for cis-DBE is almost independent of temperature. The proton spin-lattice relaxation times (T//1) in the MeOH/EBBA system were measured by a pulse NMR technique. Little temperature dependence of T//1 was found in the N/I phase region.