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- Title
Elastohydrodynamic (EHD) Traction Properties of Seed Oils.
- Authors
Biresaw, Girma; Bantchev, Grigor B.
- Abstract
The elastohydrodynamic traction coefficient (tc) properties of nine seed oils of varying chemical structures, polyalphaolefin oil (PAO) and hexadecane, were investigated using a ball-on-disk traction apparatus. The seed oils were castor oil, a triglyceride with hydroxyl functional group; jojoba, a monoglyceride; and seven triglyceride seed oils with varying fatty acid compositions. Two types of experiments were conducted at constant temperature (40 or 100°C) and constant load (10, 20, 30, or 40 N): tc as a function of slide-to-roll ratio (srr) at 1 m/s entrainment speed (u); and tc as a function of u at 50% srr. In both types of experiments, tc increased with decreasing temperature, increasing load, and increasing srr. All u vs. tc experiments gave the familiar Stribecktype profiles. A maximum in tc values was observed in some srr vs. tc experiments. Regression analysis showed excellent agreement between limiting tc (tc at 1 m/s u and 50% srr) values from these two types of experiments. Hexadecane and PAO displayed higher tc values than the seed oils, even though their viscosities were up to 80 and 7 times lower; respectively; than that of seed oils. This observation cannot be rationalized using molecular structure arguments. The results were attributed to differences in polarity between the two groups of oils. Unlike PAO and hexadecane, seed oils are polar, adsorb on friction surfaces, and lower boundary friction, which contributes to the lowering of tc in the EHD regime.
- Subjects
CASTOR oil; ELASTOHYDRODYNAMICS; CHEMICAL structure; TRIGLYCERIDES; HYDROXYL group; REGRESSION analysis; MOLECULAR structure
- Publication
Tribology & Lubrication Technology, 2013, Vol 69, Issue 11, p75
- ISSN
1545-858X
- Publication type
Article