M. Sandmann et al., PVT MEASUREMENTS ON 4-N-PENTYL-4'-CYANO-BIPHENYL (5CB) AND TRANS-4-(4'-OCTYL-CYCLOHEXYL)-BENZONITRILE (8PCH) UP TO 300 MPA, Zeitschrift fur Naturforschung. A, A journal of physical sciences, 52(10), 1997, pp. 739-747
Specific volumes are presented for 4-n-pentyl-4'-cyanobiphenyl (5CB) a
nd trans-4-(4'-octyl-cyclo-hexyl)-benzonitrile (8PCH) for temperatures
between 300 and 370 K up to 300 MPa. The p,V-m,T data were determined
for the liquid crystalline and isotropic phases, and partly also for
the solid phase adjacent to the melting curve. Stable and metastable c
rystal phases can be distinguished. The density and melting temperatur
e of the metastable form are lower than for the stable one. Volume and
enthalpy changes accompanying the phase transitions are reported as w
ell. The p, V-m, T data allow to calculate the entropy change for a hy
pothetical transition at constant volume. The molar volumes along the
nematic-isotropic phase transition T-NI(p) allow to determine the mole
cular field parameter gamma = partial derivative ln T-NI/partial deriv
ative ln V-NI.