High-pressure and temperature dependence of dielectric relaxation in supercooled di-isobutyl phthalate.

Abstract

Results are presented for isothermal, high-pressure (up to p=300 MPa), and temperature (under atmospheric pressure) measurements of complex dielectric permittivity in supercooled di-isobutyl phthalate. The relaxation times determined from the temperature study obey the temperature Vogel-Fulcher-Tammann (VFT) law. The pressure dependence of relaxation times describes the relation \ensuremath{\tau}=${\mathrm{\ensuremath{\tau}}}_{0}$exp[B/(p-${\mathit{p}}_{0}$)]. This equation gives the same ideal glass transition pressure ${\mathit{p}}_{0}$ as the generalized VFT formula proposed by Leyser et al. [Phys. Rev. E 51, 5899 (1995)]. For isobaric and isothermal absorption curves, the scaling behavior has been also tested. \textcopyright{}1996 The American Physical Society.