The Metabolemeter III: Phase Behaviour Under Pressure of bis-(4-4′-<i>n</i>-Heptyloxybenzylidene)- 1, 4-Phenylenediamine and Terephthalylidene-bis-(4-<i>n</i>-Decylaniline)

Abstract

Abstract By using a metabolemeter, the phase transitions of bis-[4, 4′-n-heptyloxybenzylidene]-1, 4 phenylenediamine (HBPD) and terephthalylidene-bis-[4-n-decylaniline] (TBDA) have been studied. The weakly first order phase transitions (SG-SF and SF-SI) and the narrowly separated phase transitions (SC-SA and SA-I) of TBDA are detectable. For HBPD, both transitions SG-SI and SI-SC are individually observed and the enthalpy changes are deduced from pressure increments at the tranformations: two triple points are detected, one directly by a change of slope in the drawing of the equilibrium curves. The pressure-temperature phase diagrams are given; for each transiton, the volume increases on increasing the temperture.