Speed of Sound, Density, and Derivative Properties of Tris(2-ethylhexyl) Trimellitate under High Pressure

Abstract

Speed of sound measurements were carried out in liquid tris(2-ethylhexyl) trimellitate (TOTM) at pressures up to 200 MPa along isotherms ranging from (293.15 to 373.15) K in order to report data of density and its derivatives. The measurements were performed with a pulse echo technique working at 3 MHz. Additional density and heat capacity measurements were carried out at atmospheric pressure in order to initiate the estimation procedure of volumetric properties from speed of sound integration. Results were compared with density measurements performed with a U-tube densimeter at pressures up to 140 MPa on the same sample. Finally, an equation that correlates density and its derivatives within their estimated uncertainties is given.

In Pursuit of a High-Temperature, High-Pressure, High-Viscosity Standard: The Case of Tris(2-ethylhexyl) Trimellitate

“…The data for lot C, 24 obtained using a U-tube Anton Paar DMA HPM densitometer with a claimed uncertainty of 0.1% at a 95% confidence level at temperatures from 293 to 373 K and pressures up to 140 MPa, agree with the results for lots A and B within the uncertainty of the latter, the maximum deviation being 0.12%.…”

“…Three different lots of TOTM have been subject to density measurements using Anton Paar U-tube instruments; they are lots A−C. Lot C was used by Bazile et al 24 for their density and speed of sound measurements and by Linẽira del Ri ́o et al 25 for viscosity measurements.…”

“…These independent measurements agree well with all the U-tube measurements mentioned earlier within their uncertainty. 24 Again, it would seem that the effect of the variability of composition of samples among lots has an effect upon the density comparable with the uncertainty in the density measurements themselves.…”

“…Most of the results have been obtained using vibrating U-tube densitometers from Anton Paar with one set of data obtained by Bair 12 with a bellows volumometer and another by Bamgbade et al 22 using another variable volume cell. Bazile et al 24 U-tube densitometer and also by integration of their speed-ofsound measurements (see section 3.6).…”

“…The fitting parameters were determined by fitting eq 12 to all speed of sound data reported by Bazile et al 24 with the same weight for each data. The fitting parameters and statistical information on the fit are also summarized in Table 8.…”