Relative Permittivity of Dimethylsulfoxide and N,N-Dimethylformamide at Temperatures from (278 to 328) K and Pressures from (0.1 to 5) MPa

Abstract

Relative permittivities (εr) were measured at two frequencies with an expanded (k = 2) uncertainty of 0.1 using a re-entrant radio frequency resonator in the pressure range (0.1 to 5) MPa at temps. from (278 to 328) K for N,N-dimethylformamide (DMF) and (293 to 328) K for dimethylsulfoxide (DMSO). At 298.15 K and 0.1 MPa, the assessed literature avs. of 38.4 ± 1.8 and 47.3 ± 1.8 for DMF and DMSO, resp., are consistent with the values of 37.2 ± 0.1 and 46.0 ± 0.1 detd. in this work. Possible sources of uncertainty are discussed. An empirical description of εr(p,T) is given that can be used to calc. the temp. and pressure derivs. of εr. Kirkwood g factors calcd. using the present data show only minimal dipole-dipole correlations for both DMF and DMSO.