The influence of pressure on dielectric relaxation for phthalate derivatives in the supercooled state

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Abstract
The dielectric relaxation of phthalate derivatives in the supercooled state has been studied at pressures up to 300 MPa, covering a frequency range from to . The behaviour of the relaxation time is very well reproduced by the relation . The analysis of the absorption curves shows that pressure increases the amplitude of the -relaxation more than the equivalent temperature change. The scaling form presented by Dixon and co-workers for the -process in supercooled liquids is re-examined in the light of pressure - dielectric relaxation data. It was found that Dixon scaling distinguishes isothermal measurements from isobaric measurements, by means of the greater strength of the second relaxation process for the pressure path.