Compressed liquid densities of squalane and pentaerythritol tetra(2-ethylhexanoate)

New experimental densities are reported for squalane and for branched pentaerythritol tetra(2-ethylhexanoate), PEB8, in the compressed liquid state over the temperature range from (278.15 to 353.15) K and for pressures up to 45 MPa. The reliability of the technique and the procedure up to 25 MPa has been verified in our previous works, and in the present work they were checked up to 45 MPa by comparing our experimental densities for heptane with literature data. A total of 297 density values have been measured with a high-pressure vibrating tube densimeter. The correction factor for density due to the sample viscosity has been considered. This factor ranges from 1 x 10(-4) to 1 x 10(-3) g center dot cm(-3) for PEB8 and from 4 x 10(-5) to 6 x 10(-4) g center dot cm(-3) for squalane over the entire Tp interval. The pressure and temperature dependencies of squalane and PEB8 densities could be accurately represented by the Tammann-Tait equation with standard deviations of 3 x 10(-5) g center dot cm(-3) for squalane and 9 x 10-5 g center dot cm(-3) for PEB8. These density data were used to analyze the isothermal compressibility, the isobaric thermal expansivity, and the internal pressure of squalane and PEB8.