Pressure behaviour of dielectric permittivity on approaching the near-critical consolute point

Results are presented of studies on dielectric permittivity (epsilon) for t he isothermal pressure (P) path of approaching the near-critical consolute point in 1-nitropropane-hexadecane solution. The pretransitional anomaly is well portrayed by the relation isomorphic to that applied in temperature ( T) studies under atmospheric pressure, However, the epsilon(P) anomaly is m uch larger, with almost negligible influence of correction-to-scaling terms and the low-frequency Maxwell-Wagner dispersion (even for f = 1 kHz), than it was observed in temperature studies at atmospheric pressure. This makes possible a reliable estimation of a critical exponent phi = 1 - alpha appr oximate to 0.88 which accounts for the critical anomaly. Discrepancies betw een the epsilon(P) and the epsilon(T) behaviour may be associated with diff erent I,positions of isothermal pressure and isobaric temperature paths of approaching the critical consolute point.