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Surface‐Enhanced Raman Spectroscopy of Tribochemically Formed Boundary Films of Refined and Unrefined Canola Oils
Author(s) -
Chua Wenhsi,
Chapman Peter,
Stachowiak Gwidon W.
Publication year - 2012
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-012-2075-1
Subject(s) - canola , raman spectroscopy , monolayer , fatty acid , chemical engineering , chemistry , triglyceride , materials science , organic chemistry , food science , nanotechnology , biochemistry , optics , engineering , cholesterol , physics
The paper reports the investigation of tribochemically formed boundary films of canola oils using surface‐enhanced Raman spectroscopy. This is the first time that metallic surfaces lubricated by plant oils have been studied using this technique. The results of this work provided strong evidence that fatty acids were liberated from the triglyceride structure during sliding to form a fatty acid soap layer on the silver surface. The study also revealed that the fatty acid chains of the unrefined canola oil were more disordered and most likely in a gauche conformation, while that of the refined canola oil were tightly packed and oriented perpendicular to the surface. It is believed that the greater presence of polar minor components in the unrefined oil, such as phospholipids, interfered with the ability of free fatty acids to form a tightly packed monolayer on the silver surface.