Boundary lubrication in a dynamic mechanical system is primarily governed by the formation of a stable tribochemical film. Polar functional groups in the triacylglycerol molecule of vegetable oil in ...conjunction with oil–additive–metal interaction during the metal rubbing process can significantly improve the wear resistance and extreme-pressure lubrication. Increasing the polar functionality of vegetable oil structure has a positive impact on wear protection resulting from stronger adsorption on metal surface as well as greater lateral interaction between the ester chains. The results reveal that ester groups of triacylglycerol molecule react with phosphate groups to form a protective fatty-phosphite layer. Antimony impregnation into the metal surface following strong complexation reaction with metal sulfide results in significant improvement in extreme-pressure characteristics due to alteration in surface metallurgy. In this case, seizure is averted even when the fluid adsorbed layer and phosphite coating is removed because of antimony induced surface hardness. The difference can be observed by analyzing the metal surface using scanning electron microscope (SEM). Selected bio fluids viz. soybean oil (SBO), thermally modified soybean oil (TMSBO) and chemically modified soybean oil (CMSBO) were investigated for potential application as industrial fluids.
This paper reports a method for the fabrication of mineral-like SrMoO4 ceramics with a powellite structure, which is promising for the immobilization of the high-energy 90Sr radioisotope. The ...reported method is based on the solid-phase “in situ” interaction between SrO and MoO3 oxides initiated under spark plasma sintering (SPS) conditions. Dilatometry, XRD, SEM, and EDX methods were used to investigate the consolidation dynamics, phase formation, and structural changes in the reactive powder blend and sintered ceramics. The temperature conditions for SrMoO4 formation under SPS were determined, yielding ceramics with a relative density of 84.0–96.3%, Vickers microhardness of 157–295 HV, and compressive strength of 54–331 MPa. Ceramic samples demonstrate a low Sr leaching rate of 10−6 g/cm2·day, indicating a rather high hydrolytic stability and meeting the requirements of GOST R 50926-96 imposed on solid radioactive wastes. The results presented here show a wide range of prospects for the application of ceramic matrixes with the mineral-like composition studied here to radioactive waste processing and radioisotope manufacturing.
Epoxidized soybean oil (ESO) was converted to a polysoap (PESO) via a two-step synthetic procedure of catalytic ring-opening polymerization, followed by hydrolysis (HPESO) with a base. Various ...molecular weights of PESO and HPESO were prepared by varying the reaction temperature and/or catalyst concentration. In addition, the counter ion chemistry was varied by changing the base used for saponification. The PESO and HPESO products were carefully characterized and identified using a combination of FTIR, ¹H-NMR, solid state ¹³C-NMR, and GPC. The effect of HPESO polysoaps on the surface tension of water and the interfacial tension of water-hexadecane was investigated as a function of HPESO concentration, molecular weight, and counter ion chemistry. HPESO polysoaps were effective at lowering the surface tension of water and the interfacial tension of water-hexadecane and displayed minimum values in the range of 20-24 and 12-17 dyn/cm, respectively, at concentration of 200-250 μM. Water-hexadecane interfacial tension was also calculated from measured surface tension data using the Antonoff, harmonic mean (HM), and geometric mean (GM) methods. Measured values agreed well with those calculated using the HM and GM methods, but not the Antonoff method.
Bio-based additives are desirable commodities due to their eco-friendly nature. These additives can demonstrate physical and chemical properties comparable to those of conventional mineral oil-based ...products. Sulfur incorporated triacylglycerol can function as an antiwear/antifriction additive for lubricants. The synthesis of four useful hydroxy thio-ether derivatives of vegetable oils, from commercially available epoxidized soybean oil and common organic thiols, is reported in this paper. The common thiols used herein were 1-butanethiol, 1-decanethiol, 1-octadecanethiol, and cyclohexyl mercaptan. Currently, there is no reported literature describing the synthesis of hydroxy thio-ether derivatives of vegetable oil. The reaction was monitored, and products were confirmed by NMR and FTIR spectroscopies. Experimental conditions involving various thiols, solvent, catalyst amount, time, and temperature were optimized for research quantity and laboratory scale-up. The synthetic process retains the vegetable oil structure, eliminates polyunsaturation in the molecule, and adds polar functional groups on triacylglycerol. These products can be used as agriculturally-based antiwear additives for lubricant applications.
Development and application of bio-based fluids in industrial and automotive sectors are rapidly increasing due to their non-toxic and biodegradable character unlike mineral oil-based products. ...Synthetic lubricant base fluid with improved high and low-temperature stability was prepared by chemical modification of epoxidized soybean oil (ESBO). The reaction was carried out in two-steps: (i) synthesis of dihydroxylated soybean oil from ESBO with HClO
4, (ii) reaction of acetic, butyric and hexanoic anhydride with the dihydroxylated product. The composition of the reaction products were confirmed by NMR and FTIR analysis. Chain length variation of the anhydrides used in the synthesis resulted in base fluids with different physical and chemical properties. Low-temperature stability was excellent for hexanoic anhydride derivative. When compared with SBO, thermal and oxidative stabilities were improved. Viscosity, volatility and other lubricant base oil properties were evaluated qualitatively. Bio-fluids based on this chemical modification offer great potential for the development of industrial fluids and products based on such fluids.
Radiation damage can occur due to the direct effect of radiation on DNA molecules, which accounts for 30–40% of lesions, or by the generation of free radicals that in turn damage DNA, which accounts ...for 60–70% 1. A comparative analysis of the induction and repair of DNA single-strand break (SSB) and double-strand break (DSB) in neuronal cells of mice (hippocampus and cerebellum) under γ-irradiation after intraperitoneal administration of 1-β-D-arabino-furanosylcytosine (AraC) and 1-β-D-arabino-furanosylcytosine/hydroxyurea (AraC/HU) combination in vivo was performed. DNA comet assay method was used to study the regularities in the formation of DNA SSB and DSB in cells from hippocampus and cerebellum of mice under the action of γ-radiation in vivo, under the influence of AraC and HU. It was found that for all types of cells used, there is a linear character in the yield of DNA lesions. It has been shown that the amount of DNA SSBs and DSBs formed during irradiation under the influence of AraC significantly increases. An additional increase in the yield of DNA SSBs and DSBs is observed under the combined action of AraC and HU.
The paper presents a reliable technology combining sol–gel synthesis and spark plasma sintering (SPS) to obtain SrTiO3 perovskite-type ceramics with excellent physicomechanical properties and ...hydrolytic stability for the long-term retention of radioactive strontium radionuclides. The Pechini sol–gel method was used to synthesize SrTiO3 powder from Sr(NO3)2 and TiCl3 (15%) precursors. Ceramic matrix samples were fabricated by SPS in the temperature range of 900–1200 °C. The perovskite structure of the synthesized initial SrTiO3 powder was confirmed by X-ray diffraction and thermal analysis results. Scanning electron microscopy revealed agglomeration of the nanoparticles and a pronounced tendency for densification in the sintered compact with increasing sintering temperature. Chemical homogeneity of ceramics was confirmed by energy dispersive X-ray analysis. Physicochemical characteristic studies included density measurement results (3.11–4.80 g·cm−3), dilatometric dependencies, Vickers microhardness (20–900 HV), and hydrolytic stability (10−6–10−7 g·cm−2·day−2), exceeding GOST R 50926-96 and ISO 6961:1982 requirements for solid-state matrices. Ceramic sintered at 1200 °C demonstrated the lowest strontium leaching rate of 10−7 g/cm2·day, optimal for radioactive waste (RAW) isolation. The proposed approach can be used to fabricate mineral-like forms suitable for RAW handling.
Development and application of biocompatible lubricants are increasing daily as a result of stringent regulations imposed on mineral oil-based lubricants with their non-biodegradable toxic wastes. ...Before consumer acceptance of vegetable oil-based lubricants, they must overcome certain poor performance characteristics such as thermal and oxidative instabilities. This work demonstrates the improved performance of epoxidized soybean oil (ESBO) over soybean oil (SBO) and genetically modified high oleic soybean oil (HOSBO) in certain high temperature lubricant application. We validated the thermal and deposit forming tendencies of these oils using micro-oxidation and differential scanning calorimetry in conjunction with identification of oxidized products by infrared spectroscopy and also discussed the function of a phenolic antioxidant in these oils. Boundary lubrication properties under high load and low speed were determined and the variations explained based on the structural differences of these vegetable oils.
An environmentally friendly water-based pathway to form the azide derivatives of soybean oil and fatty esters is reported. This entails first the formation of epoxides and then the azidization of the ...epoxides. The azidization reaction is carried out at high yields in water with only a small amount of an ionic liquid as a catalyst. The distribution of azide and alcohol functionalities on the fatty acid moiety is approximately random. This reaction has been applied to methyl oleate, methyl linoleate, soybean oil, and methyl soyate. The resulting structures have been studied by NMR.
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