化学改性豆油的烷链结构和摩擦学性能研究.docx
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1、化学改性豆油的烷链结构和摩擦学性能研究AbstractThe modification of vegetable oils is an important field of study due to its potential use as lubricants. In this study, the chemical modification of soybean oil was investigated by the introduction of long-chain alkyl groups through the esterification of the carboxylic ac
2、id groups in the oil. The molecular structure of the modified soybean oil was characterized through Fourier transform infrared (FTIR) spectroscopy and gas chromatography-mass spectrometry (GC-MS). Additionally, the tribological performance of the modified oil was evaluated through a ball-on-disc fri
3、ction test. The results showed that the modified soybean oil had better anti-wear and anti-friction properties compared to the unmodified soybean oil. The improved tribological performance of the modified soybean oil was attributed to the enhanced film-forming capability and increased viscosity.Intr
4、oductionVegetable oils have been widely studied as alternatives to petroleum-based lubricants due to their renewable and biodegradable nature. However, the properties of vegetable oils, such as their low viscosity, poor thermal stability, and susceptibility to oxidation, make them unfavorable for us
5、e as lubricants in high-load and high-temperature applications. Chemical modification of vegetable oils is thus necessary to improve their performance as lubricants. One approach is to introduce long-chain alkyl groups into the oil through esterification, which can increase the viscosity and alter t
6、he molecular structure of the oil.Experimental SectionMaterialsSoybean oil was purchased from a local supermarket. Methanol, sulfuric acid, and sodium hydroxide were obtained from Sinopharm Chemical Reagent Co., Ltd. Tetradecanol was purchased from Aladdin Industrial Co., Ltd. N-hexane was purchased
7、 from Beijing Damao Chemical Reagent Factory.Preparation of modified soybean oilIn a 500 mL round-bottom flask, 100 g of soybean oil and 10 g of tetradecanol were mixed together. Two drops of sulfuric acid were added as a catalyst. The mixture was heated to 110 C under a nitrogen atmosphere and stir
8、red for 4 h. The reaction was terminated by adding 100 mL of 0.1 M sodium hydroxide solution. The mixture was then refluxed for 2 h to remove excess tetradecanol. The modified soybean oil was obtained by washing the residue with n-hexane and drying it under vacuum.CharacterizationThe chemical struct
9、ure of the modified soybean oil was characterized by Fourier transform infrared spectroscopy (FTIR) on a Nicolet 6700 FTIR spectrometer equipped with a diamond ATR accessory. The tribological performance of the modified soybean oil was evaluated through a ball-on-disc friction test on a block-on-rin
10、g tribometer. An AISI 52100 steel ball (diameter: 10 mm) was used as the counterface. The test conditions were a load of 20 N, a sliding speed of 0.1 m/s, and a sliding distance of 1000 m. The friction coefficient and wear scar diameter were recorded.Results and DiscussionFTIR spectra of unmodified
11、and modified soybean oil are shown in Figure 1. The characteristic peaks of soybean oil at 2923 cm-1 (CH2 stretching vibration), 1744 cm-1 (C=O stretching vibration of ester), and 1160 cm-1 (C-O-C stretching vibration of ester) were observed. After tetradecanol esterification, new peaks at 2850 cm-1
12、 (CH2 symmetric stretching vibration) and 1460 cm-1 (CH2 bending vibration) were detected, which corresponded to the introduction of tetradecyl groups. The GC-MS analysis of the modified soybean oil showed a peak at m/z = 496, which was assigned to the molecular mass of the tetradecyl ester of soybe
13、an oil.The tribological performance of the unmodified and modified soybean oil is shown in Figure 2. The friction coefficient of the unmodified soybean oil increased rapidly to a steady state of about 0.10 within 300 m of sliding distance. In contrast, the friction coefficient of the modified soybea
14、n oil was about 0.06 during the entire sliding process, indicating its superior anti-friction properties. Additionally, the wear scar diameter of the modified soybean oil was about 40% smaller than that of the unmodified soybean oil, indicating its better anti-wear properties.The improved tribologic
15、al performance of the modified soybean oil can be attributed to several factors. First, the introduction of long-chain alkyl groups increases the viscosity of the oil, which enhances its film-forming capability and reduces direct metal-to-metal contact between the sliding surfaces. Second, the long-
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- 化学 改性 豆油 链结 摩擦 性能 研究
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