Dynamics of supercooled van der Waals liquid under pressure. A dynamic light scattering study

Dynamics of 1,1'-di(p-methoxyphenyl)cyclohexane (BMPC) was studied in a temperature range of 253-313 K and a pressure range of 0.1-180 MPa by means of depolarized dynamic light scattering-photon correlation spectroscopy. The temperature dependence of the mean structural relaxation times measured at constant pressures was analyzed using the Vogel-Fulcher-Tamman (FVT) equation. From the FVT analysis the values of the fragility and the glass transition temperature T-g and T-0 as well as their pressure dependence dT(g)/dP and dT(0)/dP were obtained and compared with the corresponding quantities obtained for a chemically similar but dynamically different liquid 1,1'-di(4-methoxy-5-methylphenyl)cyclohexane (BMMPC), in which two additional intramolecular relaxations were previously reported. The temperature and pressure dependence of the mean structural relaxation times was also analyzed using the Avramov model.