Graphite functionalization for dispersion in a two‐phase lubricant oligomer mixture

Abstract

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. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Improving the Mechanical/Anticorrosive Properties of a Nitrile Rubber-Based Adhesive Filled with Cerium Oxide Nanoparticles Using a Two-Step Surface Modification Method

“…To eliminate the variations in the crystalline structure of CeO 2 , the weight loss in the pristine CeO 2 (Δ R 1 ) was subtracted from the weight loss of the steamed CeO 2 (Δ M ). The obtained weight was attributed to the weight of absorbed water to nano-CeO 2 ( W H 2 O ) , normalΔ R 1 0.25em ( w eight loss of dry CeO 2 in 120 − 510 ° C ) = 0.59 normalΔ M 0.25em ( w eight loss of steamed CeO 2 in 120 − 510 ° C ) = 1.74 normalW normalH 2 normalO 0.25em ( g ) = normalΔ M − normalΔ R normal1 = normal1 . normal146 On this basis, hydroxyl group content per 1 g of nanoparticle ( N OH ) was calculated as in eq , N OH = 2 N normalA W normalH 2 normalO M normalH 2 …”

“…The number of surface OH groups was determined based on weight loss differences in TGA curves for dry and steamed CeO 2 nanoparticles. For this purpose, TGA analysis was performed at a heating rate of 10 °C/min in an argon atmosphere. , …”

Nanoceria biodistribution and retention in the rat after its intravenous administration are not greatly influenced by dosing schedule, dose, or particle shape

“…The ceria nanorod surface area per unit mass was estimated from the dimensions via the following calculation, which has been applied to estimate SSA for nanoparticles with different shapes like cubic ceria nanoparticles and graphite nanodisks. 54,69…”

Toward tuning the surface functionalization of small ceria nanoparticles

“…7 Experiments using Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis with mass spectroscopy (TGA-MS) have previously verified the presence of surface adsorbed hydroxyl groups on CNPs, and estimated their binding energies and surface densities. [8][9][10] These techniques, though, are not able to directly reveal the structure of hydroxyl-covered ceria surfaces, 11,12 nor the chemistry controlling the adsorption, distribution, and stable surface densities of hydroxyl groups as a function of environmental conditions. Quantum mechanical calculations of atomic structures and formation energies have been widely applied to study the structures and enera) Electronic mail: m.beck@uky.edu.…”