Synthetic lubricants thermal stability

PCBs are synthetic chemicals that exist as oils or waxy substances they do not occur naturally. They were once used in many products including hydraulic fluids, pigments, inks, plasticizers, lubricants, and heat transfer fluids, but their primary use was as a dielectric fluid in electrical equipment. Because of their high thermal stability, chemical stability, and electrical insulating properties, PCB fluids were used extensively in transformers, fluorescent light... 

Uses. Neopentyl glycol is used extensively as a chemical intermediate in the manufacture of polyester resins (see Alkyd resins), polyurethane polyols (see Urethane POLYMERS), synthetic lubricants, polymeric plasticizers (qv), and other polymers. It imparts a combination of desirable properties to properly formulated esterification products, including low color, good weathering and chemical resistance, and improved thermal and hydrolytic stability. 

Synthetic lubricants are made with neopentyl glycol in the base-stock polyester (24). Excellent thermal stability and viscosity control are imparted to special high performance aviation lubricants by the inclusion of polyester thickening agents made from neopentyl glycol (25,26) (see Lubrication AND lubricants). Neopentyl glycol is also used to manufacture polymeric plasticizers that exhibit the improved thermal, hydrolytic, and uv stability necessary for use in some exterior applications (27). 

Polypheny I Ethers. Both alkyl-substituted and iinsubxtiinlcd polypheny ethers are included in this class of synthetic lubricants. General preparation involves the (.llhiian ether synthesis. The unsubstituted polyphenyl ethers have outstanding thermal, oxidative and radiation resistance, however, poor low-temperature characteristics arc a major drawback. Alkyl substitution improves low-temperature viscosity, but detracts from stability. Most lubricant uses are developmental in nature and involve aircrali and aerospace applications. 

ILs viscosity iuCTeased when the chain lengA of the side chain increases, the side chain is composed of fluoride or an imidazole ring in position 2 methylation, or there is increased cation symmetry. Generally, when the cation is composed of the thermally stable imidazolium ion, the anion determines the thermal stability of the entire IL, increasing in the order TfjN >BF >PF ">halogen ions. Minami et al. [18] studied thermo-oxidative stability and volatility of ILs and found that ILs have greater thermal stability than conventional synthetic lubricants. It was also found that the stability of an ILs depends on the structures of both the anion and the cation. For example, the stability of 1, 3-dialkyl-imidazoUum is more stable than quaternary ammonium. 

To lubricate high and ultra-high vacuum pumps special lubricants with low vapour pressures at the working temperature are used, produced from naphthenic or paraffinic mineral oils by molecular distillation with good oxidative and thermal stability. Synthetic esters are another group of lubricants for vacuum pumps, the most widely used are di-n-butyl and di-n-octyl phthalates. 

Synthetic esters like polyol esters or neopentyl polyol esters are made from monobasic fatty acids and polyhedric alcohols with a neopentyl structure (see Figure 7.6). On these molecules, there are no hydrogen atoms on the beta carbon. This carbon is where thermal attack occurs on diesters and eliminating it improves the thermal stability of the molecule. Polyol esters have an increased number of ester groups versus diesters. This feature increases polarity, which will affect the lubricity of the oil at elevated temperatures and give it an advantage over PAOs. 

Synthetic bases or synthetics are products created by the chemical reaction of several ingredients. Two main classes are used for lubricants esters and synthetic hydrocarbons (in particular polyalphaolefms manufactured from ethylene). These products have excellent physical properties and exceptional thermal stability. 

AI3-17279 Benzenamine, 4-octyl-N-(4-octylphenyl)- Bis(4-octylphenyljamine Bis(p-octylphenyl)amine CCRIS 6029 Di-n-octyl diphenylamine p,p-Dioctyl-diphenylamine Diphenylamine, 4,4 -dioctyl- EINECS 202-965-5 HSDB 5341 Naugalube 438 NSC 79268. Antioxidant in automatic transmission fluids, turbine oil, and synthetic lubricants used in jet turbine engines thermal stabilizer for automatic transmission fluid at high temperatures. Crystals mp= 96-97° insoluble in H2O (<1 mg/ml) LD50 (rat orl) = 7.58 g/kg. Uniroyal. 

Still there are efforts to improve the performance of natural mineral oil-based lubricants by the synthesis of oligomeric hydrocarbons, which has been the subject of important research and development in the petroleum industry for many years and has led to commercialization of a number of synthetic lubricants. These materials are based on the oligomerization of a-olefins such as C6-C20 olefins. Industrial research effort on synthetic lubricants has generally focused on improved viscosity index, thermal and oxidative stability, and a pour point equal to or better than that of the corresponding mineral oil lubricants. 

Acid scavengers neutralize catalyst residues and prevent equipment corrosion. The choice of the acid scavengers can affect the overall acidity/basicity of a resin and influence the reactions of many of the organic additives in the system. Also, the acid scavengers as metallic stearates will impart to the polymer a certain lubricity, mold release or slip properties. As acid scavengers can be used metallic stearates (of sodium, calcium and zinc, zeolites structures (dihydro talcite, both synthetic and natural) CaO and ZnO and other metallic salts based on lactic or benzoic acid. Environmental Products has introduced PTA-210 and PTA-310 for increased thermal stability of PE, EVA, EMA, EVAA, PP, and ionomers. They are used to neutralize acidic catalyst residues. Concentration level is very low (0.2-0.5%). The hydrocaldte L-SSRH introduced by Reheis has a similar effect. 

Table 2.7. Performance of synthetic and mineral lubricant oils. Relative evaluation of viscosity, stability (thermal, oxidation, hydrolytic, volatility), lubricity (wear protection and fatigue) and environmental impact...

Applications - Esters, both dibasic and polyol esters, are used as co-base stocks with PAO or other hydrocarbon base stocks in synthetic automotive engine lubricants and industrial lubricants. Polyol esters are used in aircraft tuibine oils due to their excellent thermal and oxidative stabilities, good lubricity, high VI and excellent low temperature properties (<-40°C). Esters are also used in synthetic compressor oils for ozone-ffiendly refngeration units. Because of their high biodegradability and low toxicity, esters are often the base oils of choice for many environmentally-aware... 

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