1993 年 42 巻 480 号 p. 1109-1114
The viscosities of 0.1mol·kg-1 aqueous solutions of tetraalkylammonium bromide (R4NBr; R=Me, Et, n-Pr, and n-Bu) were measured at 5.0, 10.0, 15.0, 25.0, 40.0, and 50.0°C up to 375MPa, using a high pressure rolling-ball viscometer. The reproducibility of the viscosities under high pressure was within ±1%. The viscosity minimum observed at 5.0°C for pure water became shallow or disappeared by adding R4NBr salts and with increasing temperature. The additive effect became larger in order of the alkyl chain length of R4NBr salts. The activation energy (Ev) and activation volume (Vv) for the viscous flow of aqueous solutions of R4NBr were estimated at each pressure. The minimum of Ev at about 250MPa was observed and its minimum became shallow in order of the alkyl chain length of R4NBr. The Vv of R4NBr increased with increasing pressure.