Dielectric studies of liquid crystals under high pressure II. Low frequency relaxation process in 4-n-pentyl-4'-cyanobiphenyl in relation to theories of the nematic state

The results of high pressure dielectric studies of 4-n-pentyl-4'-cyanobiphenyl (5CB) are analysed in terms of theories of the nematic state. The retardation factor g∥ = τ∥/τ₀ and the effective, single-particle potential of mean torque were calculated at the nematic-isotropic transition temperature T_NI and along the isothermal, isobaric and isochoric paths within the nematic phase of 5CB. The potential of mean torque is compared with the order parameter known for the same conditions. The values of parameter γ relating the potential to the volume is discussed.