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Kanniah V.,University of Kentucky | Wang B.,University of Kentucky | Yang Y.,Valvoline Company | Grulke E.A.,University of Kentucky
Journal of Applied Polymer Science | Year: 2012

Fluids with thermally conductive nanoparticles can provide improved heat transfer. Practical nanofluids will be likely based on lubricating oils for the continuous phase and systems that have extended service temperature ranges. A model system based on poly(α-olefin) synthetic base oil modified with poly(dimethylsiloxane) to lower the mixture's pour point with graphite as a conductive additive was studied. Phase separation of the oligomer mixture occurred at temperatures less than -15°C. Graphite particles were etched using citric acid pretreatment to create hydroxyl and carboxyl groups on their surfaces. A coupling reaction between the hydroxyl groups on graphite and chloro groups on silanes gave rise to poly(α-olefin)-philic graphite particles. Similarly, a coupling reaction between the carboxyl groups on graphite surface and amine groups on silanes gave rise to poly(dimethylsiloxane)-philic graphite particles. SEM, FT-IR, and TG-MS measurements were used to verify the presence of coupling agents on the surface and to estimate the thickness of the coatings. Upon separation of the mixture, each functionalized graphite type migrated exclusively to its preferred phase. Copyright © 2011 Wiley Periodicals, Inc. Source

Bardasz E.,Lubrizol Corporation | Schiferl E.A.,Lubrizol Corporation | Vilardo J.S.,Lubrizol Corporation | Curtis T.T.,Lubrizol Corporation | And 3 more authors.
SAE International Journal of Fuels and Lubricants | Year: 2010

Prior technical work by various OEMs and lubricantformulators has identified lubricant-derived phosphorus as akey element capable of significantly reducing the efficiencyof modern emissions control systems of gasoline-poweredvehicles (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13).However, measuring the exact magnitude of the detriment isnot simple or straightforward exercise due to the many othersources of variation which occur as a vehicle is driven andthe catalyst is aged (1).This paper, the second one in the series of publications,examines quantitative sets of results generated using variousvehicle and exhaust catalyst testing methodologies designedto follow the path of lubricant-derived phosphorous transferfrom oil sump to exhaust catalytic systems (1). Datadiscussed include a survey of TWC technologies usedcurrently by the passenger car and light duty truck market,catalyst compatibility testing, paired vehicle dynamometertests, field trials and life cycle analysis. Finally, post-mortemanalysis of aged catalysts is used to both quantify the level ofphosphorus exposure from the oil as well as estimate the lossof performance resulting from phosphorus deposition withinthe catalyst. Results reveal a significant and beneficial impactof reduced lubricant-derived phosphorus exposure on the lifeand efficiency of various three-way catalyst technologieswhen utilized in numerous vehicle types and driving cycles.A novel statistical model was developed which provides aquantitative measure of the effect of lubricant-derivedphosphorous contamination of TWC. The overallenvironmental benefits of the specific motor oil formulationsin this study with the novel ZDP versus conventional ZDP areclearly defined by means of the life cycle analysis (LCA). © 2010 SAE International. Source

Kanniah V.,University of Kentucky | Forbus T.R.,Valvoline Company | Parker S.,Valvoline Company | Grulke E.A.,University of Kentucky
Journal of Applied Polymer Science | Year: 2011

Universal base oils that remain pourable over wide temperature ranges would have important advantages for lubrication applications. The model system used in this project was a poly(α-olefin) synthetic base oil modified with polydimethylsiloxane (PDMS) to lower the pour-point temperature. Although the blend was miscible at room temperature, phase separation occurred at temperatures lower than 258 K. Partition coefficients of such nonideal oligomer mixtures can (1) help define operating temperature ranges and (2) provide a basis for designing molecular weight distributions of each lubricant that control or prevent phase separation. The poly(α-olefin) base oil family is branched oligomers with two to five n-mers at levels greater than 1 wt %, whereas PDMS additives are linear oligomers having between 10 and 50 sequential n-mers at levels greater than 0.5 wt %. In this study, Fourier transform infrared measurements of the poly(α-olefin) and PDMS compositions in each phase provided an overall material balance. Poly(α-olefin) oligomers were detected with size exclusion chromatography with a differential refractive-index detector, and PDMS oligomers were detected with matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. The best sets of measurements for the individual oligomers in each phase were selected by minimization of the overall material balance errors. For both oligomers, components with high molecular weights were preferentially excluded from the phase rich in the other polymer and were relatively independent of temperature. The partition coefficients of poly(α-olefin) components increased with increasing oligomer length, whereas the partition coefficients of the PDMS components decreased with increasing oligomer length. Copyright © 2010 Wiley Periodicals, Inc. Source

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