MEASUREMENTS OF DIELECTRIC PERMITTIVITY NEAR THE CONSOLUTE CRITICAL-POINT OF METHANOL-CYCLOHEXANE MIXTURE

The dielectric permittivity as a function of temperature and frequency for a near critical methanol plus cyclohexane mixture was investigated. A low frequency dispersion (f//r equals 150 KHz) was found which is usually interpreted in terms of the Maxwell-Wagner polarization. The 'static' dielectric constant was measured at 2000 kHz, and a decrease of the vertical d epsilon /dT vertical value close to T//c was observed. The critical properties of the epsilon multiplied by v product was described in terms of the J. V. Sengers et al, model. The results yield the critical exponent 1 minus alpha equals 0. 89, rather than 2 beta equals 0. 65. Neglecting the specific volume anomaly leads to a slight decrease of the obtained exponent value.