Developments of Multifunctional Additives for High Quality Lube Oil

In most lubrication systems, the oil is mixed with air, in contact with air, in contact with metals and at high temperature. This is mean cause of premature lubricant, deterioration which can result in oxidation products, which are mainly acid. Hydrocarbon oxidation in the liquid phase proceeds by a radical chain reaction. In the present paper polyalkylphenol formaldehyde sulphonate and its ethoxylate were synthesized and evaluated as pour point depressant, viscosity improver and antioxidant. The efficiency of these additives depends on their chemical structure and degree of mixing (mole fraction). Values of surface tension of these additives were measured in oil phase and consequently CMC was determined for all additives and their mixtures. A novel method of inhibiting oxidation was proposed. The author suggests the mechanism of inhibiting oxidation according to surface activity of additive in oil phase. More confirmations for suggested mechanism were investigated by measuring the area occupied per molecule of additive at oil phase. The results indicate that the compatibility of sulphonate with ethoxylate group and forming stable micelle which acts as wax dispersant and improver viscosity.

Development of Antioxidants Synthesized by Phase Transfer Catalysts for Lubricating Oil

The oxidation stability of lubricating oil has a critical influence on the oil performance during service. In this paper, dibenzyl-S-phenyl thioglyconitrile and other derivatives were prepared by phase transfer catalysts and investigated as antioxidants. These compounds were added to oil in different concentrations. The antioxidants activities of different dosages were evaluated and the mechanism was suggested according to micelle and its thermodynamics. The oxidation of the oil has been carried out at different time intervals. The degradation of the oil has been monitored by total acid formation. Oxidation stability of lube oil was largely affected by sulphur and concentration of aromatic hydrocarbons in oil, with the increased sulphur content increasing oxidation stability. The prepared compounds gave higher oxidation stability than imported compound (IRCANOX L 135-CIBA).

Efficiency of Amphoteric Surfactants as Flow Improvers and Pour Point Depressants

Some amphoteric surfactants (N-Decyl-N-benzyl-N-methylglycine(AB) and N-Dodecyl-N-benzyl-N-methylglycine(CD) were prepared in the laboratory. The physicochemical chemical characteristics were investigated. The adsorption behavior of these surfactants at oil/air interface was investigated by measuring the surface tension and interfacial tension as function of concentration. Surface properties, in particular the critical micelle concentration (CMC), the maximum surface excess (ΓCMC) and the minimum surface area (AMIN) were measured. It is found that the surface and thermodynamic properties of the prepared surfactants depend on their hydrocarbon chain length. Also it is found that there is a good relation between surface properties of the additive and their efficiency in depressing the pour point. The mechanism of the depressants action has been suggested according the adsorption of each additive. Adsorption of the additive on the surface of the wax particles inhibits their growth and alters the crystal habits through micelle core. As the results the surface and thermodynamic parameters confirm the suggested mechanism and the decreasing of pour point. This is resulted in a multilayer, more isotropic wax crystal, and thus only a fixed amount of wax separates at any given temperatures. The results were discussed in terms of adsorption isotherm.

Evaluation of Additives as Corrosion Inhibitors/Antioxidants for High Quality Nano Emulsifiable Oils of Metalworking Fluids

Surfactants used for formulation metal working fluids. In the present paper, the inhibitive effect of synthesized anionic surfactant P-decyloxy p-sodium sulphonateazobenzene with chemical structure H21C10O-Ph-N=N-Ph-SO3Na and 1-ethyl-1-dodecyl-2-sulphonate-4-(hydroxyl ethyl)-piprazine on the corrosion of carbon steel in sulphuric acid solution is measured by the weight loss method. The relationships between the concentrations of these inhibitors and their surface properties, thermodynamic properties, surface coverage and inhibiting efficiency, have been investigated. The results indicate that P-decyloxy p-sodium sulphonate azobenzene is superior to 1-ethyl-1-dodecyl-2-sulphonate-4-(hydroxyl ethyl)-piprazine at high acid concentration. These inhibitors blend with coupling agent to produce water miscible cutting fluid. Values of surface tension of these additives were measured in water phase and consequently CMC was determined for all inhibitors. The efficiency of these inhibitors depends on their chemical structure and the presence of hydrophilic group to association of the surfactant with metal surface, hence very good wetting properties. The anti-corrosion characteristic of surfactants increases with increasing polar linkages in the aromatic moieties forming chelated and coordinated layer. This is due to the increase in number of sites to chemisorption on the metal surface. These studies have led to much clear evidence of the intimate relationship between the chemical structure of the surfactants and their efficiency. More confirmation for suggested mechanism was investigated by measuring the area occupied per molecule of the surfactant at aqueous phase. The results indicate that the amphoteric surfactant more efficient than anionic surfactant. The antioxidants activities of different dosages of inhibitors were evaluated and suggested mechanism according to their thermodynamics parameters. The oxidation of the oil has been carried for different time intervals. The degradation of the oil has been monitored by total acid formation.