High pressure physicochemical properties of biodiesel components derived from coconut oil or babassu oil

Abstract The four main components of biodiesel coming from coconut oil or babassu oil studied in this work are methyl caprylate, methyl caprate, methyl laurate, and methyl myristate. The speeds of sound in methyl caprylate, methyl caprate, methyl laurate were measured at pressures up to 101 MPa within the temperatures from 293 to 318 K and in methyl myristate at pressures up to 91 MPa and at temperatures from 298 to 318 K. The densities were measured under atmospheric pressure in the temperature range from 273 to 363 K for methyl caprylate, methyl caprate, between 283.15 and 363.15 K for methyl laurate and at temperatures from 293.15 to 363.15 K for methyl myristate. The densities, isobaric thermal expansivities, and isentropic compressibilities as a function of temperature and pressure have been calculated using the experimental results. The results obtained show that for a given temperature, the differences between densities of the methyl caprylate, methyl caprate, methyl laurate, and methyl myristate increase with increasing pressure, while for a given pressure the differences between densities of the methyl esters under test decrease with increasing temperature, which leads to cross of density isobars.