Abstract
This study presents comparative evaluation of thermal conductivity (TC) and dynamic viscosity enhancement of high-oleic soybean oils (HOSO) by dispersing five nanoparticles—two graphene nanoplatelets (xGnP, GnP), MoS2, TiO2, and Al2O3—to formulate high-performance nanofluids for minimum quantity lubrication (MQL) machining. TC was measured for 1–7 wt.% nanoparticle concentrations over 25–75 °C (10 °C increments) using a Transient Hot Wire meter, and viscosity was measured for 1–4 wt.% at 25, 45, and 75 °C using a ViscoQC 300 rotational viscometer. Ultrasonic dispersion ensured uniform nanoparticle distribution. Results show that TC decreases linearly with temperature but increases nonlinearly with nanoparticle wt.% concentration. Viscosity decreases exponentially with increasing shear rate and temperature but rises nonlinearly with nanoparticle wt.% concentration. The highest TC enhancement at 7 wt.% occurred with xGnP/HOSO nanofluids (~ 214% at 25 °C, ~ 196% at 75 °C) followed by GnP/HOSO (~ 37%, ~ 21%), MoS2/HOSO (~ 16%, ~ 9%), TiO2/HOSO (~ 12%, 10%), and Al2O3/HOSO (~ 12%, ~ 7%). xGnP/HOSO achieved TC values of 0.53 W m−1 K−1 (25 °C) and 0.47 W m−1 K−1 (75 °C), approaching conventional emulsion coolants (CEC) levels [0.62, 0.66 W m−1 K−1]. At 4 wt.%, xGnP/HOSO showed the highest viscosity enhancement (622% at 25 °C, 784% at 75 °C), followed by TiO2/HOSO (18.6%; 29.4%), MoS2/HOSO (12.3, 9.9%), GnP/HOSO (11.6, 5.9%), Al2O3/HOSO (8.8, 3.7%). Nanofluid formulation showed that xGnP concentrations above 5 wt.% reduce flowability. xGnP showed superior enhancement of TC and viscosity compared to MoS2 and metal oxides. xGnP/HOSO at 5 wt.% are recommended as sustainable CEC substitute for nanofluid-based MQL machining.
Recommended Citation
A. C. Okafor et al., "Thermal Conductivity and Viscosity Characterization of Soybean Oil Nanofluids Dispersed with Graphene Nanoplatelets, MoS2, TiO2 and Al2O3 Nanoparticles for MQL Machining," Discover Nano, vol. 21, no. 1, article no. 303, SpringerOpen; Discover, Dec 2026.
The definitive version is available at https://doi.org/10.1186/s11671-026-04754-9
Department(s)
Mechanical and Aerospace Engineering
Second Department
Chemical and Biochemical Engineering
Publication Status
Open Access
Keywords and Phrases
Dynamic viscosity; Graphene nanoplatelets-Al2O3-MoS2-TiO2-nanoparticle; High oleic vegetable oils; Minimum quantity lubrication machining; Nanofluid; Thermal conductivity
International Standard Serial Number (ISSN)
2731-9229
Document Type
Article - Journal
Document Version
Final Version
File Type
text
Language(s)
English
Rights
© 2026 The Authors, All rights reserved.
Creative Commons Licensing
This work is licensed under a Creative Commons Attribution 4.0 License.
Publication Date
01 Dec 2026
Included in
Chemical Engineering Commons, Civil and Environmental Engineering Commons, Engineering Mechanics Commons, Materials Chemistry Commons, Materials Science and Engineering Commons, Mechanical Engineering Commons
Comments
Missouri University of Science and Technology, Grant NSF CMMI2218786