Effects of a Star Styrene Butadiene Additive on the Thermodynamic Properties of a Group III Mineral Base Oil
AIChE Annual Meeting
2023
2023 AIChE Annual Meeting
Annual Student Conference: Competitions & Events
Undergraduate Student Poster Session: Fuels, Petrochemicals, and Energy
Monday, November 6, 2023 - 10:00am to 12:30pm
Automotive transmission fluids are primarily composed of mineral base oils and often
contain additives that help improve the performance of these oils. In this study, the effect of a
star styrene-butadiene additive (MW=50,000 g/mol) on the thermodynamic properties of a
petroleum-derived Ultra S4 mineral base oil was investigated. The interest has been on their
properties under pressure.
The oils were evaluated at 1, 2, and 5 wt % addition levels of the styrene-butadiene
modifier copolymer. Specific properties that have been evaluated include the density, isothermal
compressibility, isobaric expansivity and the internal pressure.
Densities were determined at temperatures from 298 to 398 K over a pressure range from
10 to 35 MPa using a high-pressure variable-volume view-cell. The internal volume of the cell
is changed with a movable piston, the position of which is altered with the aid of an automated
pressure generator. The piston position and thus the internal volume of the cell is monitored with
an LVDT (linear variable differential transformer) sensor at any given temperature and pressure.
Densities are then determined form the initial mass loading which is known.
Density data are then correlated with the Sanchez-Lacombe Equation of State, which is a
lattice fluid equation of state that is effective in accounting for and describing the pressure
effects. The correlation equations are then used to evaluate the derived thermodynamics
properties, namely, compressibility, expansivity and internal pressure.
The results showed that the inclusion of the additive increased the density of the base oil
at a similar level for all these concentrations. Isothermal compressibility of the base oil also
increased for the 1 and 2 wt % addition levels, but there was essentially no change for the case of
5% additive. The additive caused a decrease in isobaric expansivity of the base oil at all
concentrations, with the 1% addition causing the greatest decrease. The internal pressure also
showed a decrease at all concentrations, with the greatest decrease occurring at the 2% addition
followed by the 1% addition.
contain additives that help improve the performance of these oils. In this study, the effect of a
star styrene-butadiene additive (MW=50,000 g/mol) on the thermodynamic properties of a
petroleum-derived Ultra S4 mineral base oil was investigated. The interest has been on their
properties under pressure.
The oils were evaluated at 1, 2, and 5 wt % addition levels of the styrene-butadiene
modifier copolymer. Specific properties that have been evaluated include the density, isothermal
compressibility, isobaric expansivity and the internal pressure.
Densities were determined at temperatures from 298 to 398 K over a pressure range from
10 to 35 MPa using a high-pressure variable-volume view-cell. The internal volume of the cell
is changed with a movable piston, the position of which is altered with the aid of an automated
pressure generator. The piston position and thus the internal volume of the cell is monitored with
an LVDT (linear variable differential transformer) sensor at any given temperature and pressure.
Densities are then determined form the initial mass loading which is known.
Density data are then correlated with the Sanchez-Lacombe Equation of State, which is a
lattice fluid equation of state that is effective in accounting for and describing the pressure
effects. The correlation equations are then used to evaluate the derived thermodynamics
properties, namely, compressibility, expansivity and internal pressure.
The results showed that the inclusion of the additive increased the density of the base oil
at a similar level for all these concentrations. Isothermal compressibility of the base oil also
increased for the 1 and 2 wt % addition levels, but there was essentially no change for the case of
5% additive. The additive caused a decrease in isobaric expansivity of the base oil at all
concentrations, with the 1% addition causing the greatest decrease. The internal pressure also
showed a decrease at all concentrations, with the greatest decrease occurring at the 2% addition
followed by the 1% addition.