Simple measurement of the pressure dependence of density for fatty acid esters

A simple variable-volume method using a polytetrafluoroethylene capsule as a sample cell was applied to measure the pressure dependence of liquid density (rho). The method was applied to 2-ethylhexyl benzoate at 313, 333, and 353 K, and the reproducibility of its volume change was confirmed at pressures of up to 400 MPa. A correction term for the apparatus was also estimated. The uncertainty in the high-pressure rho measurements was estimated to be similar to +/- 1%. Using the developed method, the rho values of methyl laurate at pressures of up to 400 MPa at 313 and 333 K, as well as those of methyl linoleate at pressures of up to 400 MPa at 313, 333, and 353 K, were measured. The results were in good agreement with the literature values in the low-pressure range. The proposed method enables the determination of the high-pressure rho of liquids with greater ease than previously possible.