1. Thermal-oxidation mechanism of dioctyl adipate base oil
- Author
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Yaling Xiang, Hongfei Shang, Shengpeng Zhan, Bingxue Cheng, Xuzheng Qian, and Jian Li
- Subjects
Thermal oxidation ,Acid value ,Mechanical Engineering ,Base oil ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Surfaces, Coatings and Films ,Molecular dynamics ,Dioctyl adipate ,chemistry.chemical_compound ,020303 mechanical engineering & transports ,0203 mechanical engineering ,chemistry ,Polymerization ,Chemical engineering ,Gas chromatography–mass spectrometry ,ReaxFF ,0210 nano-technology - Abstract
The ester base oil of dioctyl adipate (DOA) was oxidized in an oven at 200 °C for 30 h, and variations in the physicochemical and tribological properties were studied. To investigate the thermal-oxidation mechanism, the thermal-oxidation products were analyzed by gas chromatography–mass spectrometry (GC−MS), and the thermal-oxidation process was simulated using visual reactive force field molecular dynamics (ReaxFF MD). The results indicated that the total acid number (TAN) increased significantly because of the presence of 14% carboxylic acids and low molecular weight monoesters. The tribological properties were improved by the formation of the strongly polar carboxylic acids. Additionally, the increase in kinematic viscosity was limited due to the formation of high molecular weight polymerization products and low molecular weight degradation products. Thermal-oxidative degradation and polymerization mechanisms were proposed by combining ReaxFF MD simulations and GC−MS results.
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