新型飞机燃油抗氧剂膦化物的氧化反应的研究

膦化物为高性能飞机燃油潜在的抗氧剂,能显著地改善飞机燃油的高温稳定性能。实验结果表明,膦化物在燃油介质中的氧化反应有两种反应类型同时进行,即:自由基链反应及膦化物与氧气的直接作用。在相对较低温度时,膦化物与基态氧发生自由基链反应,膦化物很快被氧化为氧化膦;在相对较高的温度,膦化物与激发态氧直接作用,通过三元环状中间体而最终生成氧化膦和次磷酸酯。

高性能飞机燃油新型抗氧剂的研究

膦化物为高性能飞机燃油潜在的抗氧剂,通过31P NMR检测膦化物在高温燃油介质中的氧化反应,结果表明,氧化产物主要为氧化膦及少量的次膦酸酯,两产物的生成比例与反应物起始浓度有关,而且反应通过中间物—三元的环二氧膦化物进行,因此最佳的燃油高温抗氧剂为具有合适的空间位阻效应和电子效应从而能与氧气生成相对稳定的环二氧膦化物的膦化物。

Determination of the antioxidant activity based on the content changes in fatty acid methyl esters in vegetable oils

Free radicals, which are generated in several biochemical reactions in the body, have been implicated as mediators of many diseases, including cancer, atherosclerosis and heart diseases. Although the endogenous antioxidants can scavenge these free radicals, they are often insufficient to maintain the in vivo redox balance. The antioxidant activity(AOA) was examined by addition of each tested antioxidants [alpha-tocopherol(α-T), beta-tocopherol(β-T), gamma-tocopherol(γ-T), delta-tocopherol(δ-T), butylated hydroxyanisole(BHA), 2,6-di-tert-butyl-4-methylphenol(BHT), and ascorbyle palmitate(AP)] to four types of different vegetable oils(sunflower oil, soybean oil, corn oil and olive oil). Moreover, content changes in fatty acids were then investigated every 3 months during the storage period. The results showed that the AOA was different among the tested antioxidants. The AOA for BHA was the most for different types of oil compared with other antioxidants, whereas the δ-T possessed the lowest AOA.