The rheological behaviour of four blends of multigrade oils containing different commercial viscosity index improvers has been studied for increasing shear rate and temperature. Polyalkylmethacrylate has been found to demonstrate different behaviour to styrene‐isoprene, styrene‐butadiene and ethylene‐propylene copolymers. Oil blends for all these hydrocarbon copolymers have shown non‐Newtonian behaviour with increasing shear rate (0 to 35,000 s−1) at low and moderate temperatures (−15 to 40°C), i.e. their viscosities were subject to a significant decrease, while the viscosity of the polyalkyl‐methacrylate blend showed a limited decrease. With increasing shear rate at high temperature (100°C), all the formulated blends behaved as Newtonian fluids, i.e. with nearly constant viscosities. Increasing shear rate can also change the behaviour of some hydrocarbon copolymers from thickeners to viscosity index improvers.
Some performance properties for turbine, hydraulic and gear oils were correlated with changes in chemical structure for incorporated base oils. Blends with different viscositygrades were formulated from different neutral oils, brightstocks and additives.Different statistical approaches were used to evaluate the degree of fit for these correlations. The derived models were considered at a minimum of 99% confidence. Results clarified the role of non-hydrocarbons and aromatic compounds, either by type or by content, in changing the performance behaviour for tested industrial oils. AbstractChemical structure, performance, brightstocks, additives, demulsibility, air release, foam tendency Keywords Industrial oils are generally blends of neutral base oils, brightstocks and some specific additives. Base oils and brightstocks are mixtures of paraffinic, naphthenic and aromatic hydrocarbons, beside minor amounts non-hydrocarbons, e.g. sulphur, nitrogen and oxygen compounds. Most of these non-hydrocarbons have a high degree of polarity due to their molecular structure. Accordingly, these compounds are undesirable due to their high reactivity. Some of the aromatic hydrocarbons are also undesirable, e.g. diand polyaromatics. Many publications have attributed the deterioration in most of the oils' performance to these types of aromatics beside the non-hydrocarbon compounds.1-7.10-18Brightstocks, as heavy distillates, are incorporated in the formulations of finished oils to adjust their viscosities to the required levels. But, generally, brightstocks contain relatively considerable amounts of undesirable aromatics and non-hydrocarbons. Over the last decade, the effect of lubricating oils' chemical structures on the performance of finished lubricants has been given attention in relation to the following causes:LLimited availability of crudes suitable for neutral oils and brightstocks production. 2.Preference for using moderately severe techniques in refining, e.g. solvent extraction, as these techniques have resulted in energy saving.
Substituted polysaccharides with different molecular weights (mol. wt 12 OOC-15 500) were synthesised by reacting aliphatic acid chlorides with different carbon numbers (CIZ-CIR) with dextrin. The resulting polymers were purified and tested as pour point depressants and flow improvers for middle distillates (gas oils). Comparative evaluation of these polysaccharides with some commercial additives showed their good activity, especially as flow improvers.
Heavy alkylated benzene, which is accumulated as a by‐product from linear alkyl benzene synthesis, was evaluated as a starting material for anionic liquid sulphonate surfactants. Chemical structure analysis by GC/MS showed that the by‐product contains eight different paraffinic side‐chains, within the carbon range C12–C15. Accordingly, sulphonation conditions for it were adjusted to optimize the reaction yield and product quality. Liquid surfactant formulations based on these anionic sulphonates were established by incorporating other necessary ingredients. The formulations developed have shown high efficiency as detergents, wetting agents and emulsifiers.
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