Vapor-Pressure Measurements and Modeling of Dipentaerythritol Ester Lubricants

Abstract

The aim of this work is to present new vapor-pressure measurements and provide a good description of the volumetric and phase behavior of dipentaerythritol ester (DiPEs) lubricants, using the Statistical Associating Fluid Theory (SAFT) model (PC-SAFT and SAFT-VR versions). Characteristic parameters of these versions were optimized for dipentaerythritol hexapentanoate (DiPEC5), dipentaerythritol hexaheptanoate (DiPEC7), and dipentaerythritol isononanoate (DiPEiC9), using experimental vapor pressures and densities. With these parameters, compressed densities were predicted. Experimental vapor pressures, determined by a gas saturation apparatus, range between 2 × 10−5 Pa and 16 Pa, whereas the absolute deviations obtained in the correlations for both versions of the model (PC-SAFT and SAFT-VR) are between 10−6 Pa and 1 Pa. In the case of saturated densities, the average absolute deviation (AAD) values, for both models, range from 0.2% to 1.3%, except for DiPEC7, where the AAD is 4.4% when using the SAFT-VR model. The SAFT-VR version gives slightly better correlations, although we must note that this version has four parameters, whereas the PC-SAFT version has three.

Temperature and Pressure Dependence of the Viscosities of Krytox GPL102 Oil and Di(pentaerythritol) Hexa(isononanoate)

“…The second, di­(pentaerythritol) hexa­(isononanoate) (isononanoic acid, 1,1′-[2-[[3-[(1-oxoisononyl)­oxy]-2,2-bis­[[(1-oxoisononyl)­oxy]­methyl]­propoxy]­methyl]-2-[[(1-oxoisononyl)­oxy]­methyl]-1,3-propanediyl] ester or diPE i C 9 , Figure ), is a stable ester that does not have the disadvantage above. It has been used as a lubricant component and is more viscous than Krytox GPL102 under the same conditions. Measurements were suggested to the author by Professor Josefa Fernández of the University of Santiago de Compostela, Spain, as the pVT data, necessary for the buoyancy correction required by the falling body viscometer employed in this laboratory, have been measured in hers.…”

Solubilities of Carbon Dioxide in a Dipentaerythritol Ester and in a Polyether

“…The solubility was carried out using an isochoric technique which determines the amount of gas dissolved in a known volume of liquid from a fixed volume of gas . This procedure is adequate when, as in the present case, the vapor pressure of the solvent can be considered negligible. , García et al measured the vapor pressures of DiPEC7, finding values even lower than those of PEs. Taking into account the molecular structure of PAG1, we also expect very low vapor pressures for this oligomer.…”

“…8 This procedure is adequate when, as in the present case, the vapor pressure of the solvent can be considered negligible. 25,26 Garcı ´a et al 27 measured the vapor pressures of DiPEC7, finding values even lower than those of PEs. 28 Taking into account the molecular structure of PAG1, we also expect very low vapor pressures for this oligomer.…”

“…In the case of the DiPEC7, the volume of the absorbed gas in the solvent, v abs gas , is calculated as the partial molar volume in the liquid phase at infinite dilution. Thus, as in our previous articles, it was calculated using the correlation reported by Heidemann and Prausnitz based on the work of Lyckman et al To do so, it is necessary to know the cohesive energy density of the solvent, , c 2 , which was evaluated at each temperature from the enthalpies of vaporization and the density values measured by García et al and Fandiño et al, respectively. For PAG1 another method was used to calculate v abs gas because its enthalpies of vaporization are unknown.…”

Synergistic effect of dipentaerythritol and montmorillonite in EVOH‐based nanocomposites

“…Moreover, DPE has some further advantages: it is characterized by a low volatility and excellent heat and oxidation stability. Indeed, thanks to such features DPE is used in several applications: for example, its esters are suitable base oils for aviation gas turbine lubricants, high‐temperature chain oil, high‐temperature greases (for example, heat conduction greases) . DPE is also a component in some formulations in intumescent fire retardant (IFR) coatings, such as an ammonium phosphates/DPE/melamine blend.…”