J. Dufour et al., SHEAR VISCOSITY AND DIELECTRIC-RELAXATION TIME OF DIBUTYL PHTHALATE DOWN TO GLASS-TRANSITION TEMPERATURE, Journal of molecular liquids, 62, 1994, pp. 75-82
We studied the shear viscosity and the main dielectric relaxation time
of dibutyl phthalate from 97 degrees C down to -96 degrees C (near it
s glass transition temperature Tg). A visco penetrometer and a dielect
ric spectrometer built in our laboratories allowed us to obtain experi
mental data in the ranges 10-10(9) 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 temperatu
re on twelve decades; they are well fitted by the Cohen and Grest rela
tion. These fits obtained on a large temperature range show that there
is a strong correlation between viscosity and dielectric relaxation t
ime. Furthermore it appears that the dielectric relaxation time distri
bution is broadening in the vicinity of Tg.