Effect of Pressure on Dielectric Properties and Volume of 1-Propanol and Glycerol

Dielectric constants and loss have been measured to pressures of 1000 kg/cm2 at audio- and radio-frequencies from 212 to 240°K for glycerol and 124 to 210°K for 1-propanol. Compressions to 1000 kg/cm2 have been measured to room temperature. The increases in static dielectric constant are less than predicted from density increase alone, and the differences are discussed in terms of molecular compression and liquid structure effects. Larger increases of relaxation time with pressure are found at lower temperatures. Constant volume relaxation times do not conform to a simple rate law, and cannot be explained by activation energies depending only on volume. Glycerol shows small, temperature independent, percentage volume decrease with pressure over the whole range; 1-propanol becomes much less compressible at low temperatures.