DENSITY EFFECTS IN THE LANDAU-DE-GENNES-THEORY NEAR THE NEMATIC-ISOTROPIC PHASE-TRANSITION

Density effects at the nematic-isotropic phase transition is studied b y means of Landau-de Gennes theory. The analysis shows that the densit y variation shifts the nematic-isotropic transition temperature T-NI a nd changes the Landau-de gennes free energy expansion coefficients. Th e possibility of the tricritical behaviour of the nematic-isotropic ph ase transition is also discussed by the density variation. The low val ue of T-NI - T (T* is the absolute stability limit of the isotropic p hase) and the various thermodynamic quantities are also calculated to compare with the experimental data.