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Transmissions and Transmission Fluids
Published in Leslie R. Rudnick, Synthetics, Mineral Oils, and Bio-Based Lubricants, 2020
Scott Halley, Timothy Newcomb, Richard Vickerman
Lubricants are hydrocarbons and will react with oxygen at sufficiently high temperatures. The temperature where this becomes significant depends on the nature of the base oil. Oxidation inhibitors act to disrupt the reaction of oxygen with the base oil. Chemically this is a free radical reaction and the oxidation inhibitors (antioxidants) are molecules that either scavenge free radicals or decompose hydroperoxides.
Fundamental Aspects
Published in Bruno Langlais, David A. Reckhow, Deborah R. Brink, Ozone in Water Treatment, 2019
Guy Bablon, William D. Bellamy, Marie-Marguerite Bourbigot, F. Bernard Daniel, Marcel Doré, Françoise Erb, Gilbert Gordon, Bruno Langlais, Alain Laplanche, Bernard Legube, Guy Martin, Willy J. Masschelein, Gilbert Pacey, David A. Reckhow, Ciaire Ventresque
Initiators. The initiators of the free-radical reaction, that is, the compounds capable of inducing the formation of a superoxide ion O2− from an ozone molecule (see Figure II–4), are inorganic compounds (for example, hydroxyl ions [OH−], hydroperoxide ions [HO2−], and some cations) and organic compounds (for example, glyoxylic acid, formic acid, and humic substances). Ultraviolet radiation at 253.7 nm is also capable of initiating the free-radical process. This activation of ozone by UV light, plus the combination of H2O2/HO2−, constitutes the basis of the advanced oxidation processes that will be described later in this section.
Study on the Effect of Oxygen on Free Radical Generation in Coal
Published in Combustion Science and Technology, 2023
Yandan Tao, Zhian Huang, Yinghua Zhang, Hao Ding, Xiangming Hu, Yukun Gao, Cuanwu Sun, Dongfang Cao
As shown in Figure 8, the concentration of free radicals did not increase with the increase in oxidation time. At 90 and 110°C, the variation trend of the free radical concentration was consistent. At 1 to 5 h, the concentration of free radicals decreased with the increase in oxidation time. Then, at 5 to 9 h, the concentration of free radicals increased slowly with the increase in oxidation time. Both concentrations of free radicals for the two curves at 1 h are the highest, which shows that the free radical reaction is active at 1 h. At 1 to 5 h, with the increase in oxidation time, the free radical reaction slows down, and the free radical concentrations begin to decline. Then, at 5 to 9 h, the free radical reaction increases slowly, with the free radical concentration slowly rising, which suggests that the free radical concentration is not linearly associated with the oxidation time. It is not a case of the longer the oxidation time, the more intense the free radical reaction; instead, there are stages. In a certain period, the free radical reaction is intense, and after this period, the free radical reaction weakens. The free radical concentration at 110°C is much higher than that at 90°C, which is consistent with the influence trend of temperature change on the free radical concentration.
Biobased Poly-phosphonate Additives from Methyl Linoleates‡
Published in Tribology Transactions, 2019
Girma Biresaw, Grigor B. Bantchev, Rogers E. Harry-O’Kuru
A schematic of phosphonate synthesis is provided in Scheme 1. It is a free radical reaction with t-BP as the free radical initiator. Several factors were considered for the selection of t-BP as the initiator. For example, the decomposition products of t-BP (benzoic acid, acetone, and methane) are easy to remove from the product mixture by simple distillation. The effect of phosphite alkyl group chain length on reactivity was investigated. The dimethyl phosphite, which is the most polar of the three, was immiscible with methyl linoleate at low temperatures. However, when the temperature was raised above 60 °C, it became miscible and reacted well. Reactions were conducted by adding portions of the phosphite at various time intervals. This practice seemed to indicate that the reactivity of the phosphites with methyl linoleate was different and increased in the order di-n-butyl phosphite < diethyl phosphite < dimethyl phosphite. However, analysis of the data indicated no difference in the reactivity among the phosphites. The observed trend was a reflection of the relative molar concentration of the phosphites in the reaction mixture, because similar weight portion of phosphites were added during the synthesis. Thus, both molar concentration and reactivity of the dialkyl phosphites increased in the order di-n-butyl phosphite < diethyl phosphite < dimethyl phosphite. Detailed discussion of dialkyl phosphite reactivity is provided in Bantchev, et al. (23).
Oil-in-gold nanoparticle solution emulsion stabilized with amphiphilic polymers and its stability under NIR irradiation
Published in Journal of Dispersion Science and Technology, 2018
PHEA and P(HEA/PMA) were prepared by a free radical reaction. HEA and PMA were co-dissolved in 50 mL of DMF contained in a 250 mL three-neck round-bottom flask so that the molar ratio was 100:0, 97:3, 95:5, 93:7, and 90:10. The monomer solution was degassed with N2 stream for 30 minutes, and AIBN (40 mg, an initiator) was added to the degassed solution. The flask was immersed in an oil bath thermostated at 75°C, and the mixture was stirred using a magnetic bar for 12 hours with reflux. The reaction mixture was cooled down to room temperature and it was poured into 600 mL of diethylether contained in a 1 mL beaker for the precipitation of the polymer. The suspension of the polymer precipitate was filtered through a filter paper and the precipitate was obtained as a cake. For purification, the cake was dissolved in DMF, re-precipitated in diethylether, and filtered. The cake was dried in a vacuum oven thermostated at 50°C. Polymer prepared from a reaction mixture whose HEA to PMA molar ratio was 100:0, 97:3, 95:5, 93:7, and 90:10 was abbreviated to P(HEA/PMA)(100/0), P(HEA/PMA)(97/3), P(HEA/PMA)(95/5), P(HEA/PMA)(93/7), and P(HEA/PMA)(90/10), respectively.