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We studied the shear viscosity and the main dielectric relaxation time of dibutyl phthalate from 97°C down to −96°C (near its glass transition temperature Tg). A visco penetrometer and a dielectric spectrometer built in our laboratories allowed us to obtain experimental data in the ranges 10-109 Pa.s for viscosity and 1 mHz–2 MHz for dielectric relaxation time. All these data and those of different authors give viscosity and dielectric relaxation time versus temperature on twelve decades; they are well fitted by the Cohen and Grest relation. These fits obtained on a large temperature range show that there is a strong correlation between viscosity and dielectric relaxation time. Furthermore it appears that the dielectric relaxation time distribution is broadening in the vicinity of Tg.

We studied the complex permittivity of alkylhydrazines/water mixtures from room temperature down to − 120°C between 50 mHz and 2 MHz, in the mole fraction range 0.1 ≤ x ≤ 1. The addition of a second suitable component decreases and even eliminates, at sufficient concentration, the anomalies of pure water and allows, according to Oguni and Angell, to separate the “normal” and the “anomalous” parts of water physical properties. The static permittivity of alkylhydrazines - water mixtures (with monomethylhydrazine and 1,1-dimethylhydrazine) leads to estimate, by extrapolation at x = 0, the static permittivity of normal supercooled water below its homogeneous nucleation temperature, in spite of chemical associations present in the solutions. The values calculated by this method are in good agreement with our previous results obtained on alcohol/water mixtures and the data predicted by the random network model of Sceats and Rice.