Thermophysical Properties of Two Poly(alkylene glycol) Derivative Lubricants from High Pressure Acoustic Measurements

The speeds of sound in two poly(alkylene glycol) derivatives (triethylene glycol dimethyl ether and tetraethylene glycol dimethyl ether) were measured, at temperatures from 293.15 to 353.15 K and pressures from atmospheric up to 100 MPa, using a pulse technique operating at 3 MHz, with an estimated error of less than ±0.2%. From these measurements, and using literature density and heat capacity data at 0.1 MPa and at several temperatures, PVT surface and isentropic and isothermal compressibilities of each compound were estimated in the same experimental ranges of pressure and temperature.