Synthesis and Characterization of Some Multifunctional Additives for Engine Oil

Abstract

The petroleum additive industry is a significant operating sector of the world economy. Engine oil is basically a combination of base oil and additives. Additives are necessary to provide performance beyond what base oils alone are able to offer. In the present work we aimed to prepare some lube oil additives through preparation of different alkyl acrylates by esterification of acrylic acid with different alcohols (decanol, dodecanol, hexadecanol and octadecanol). Then, anilimide was prepared by the reaction of maleic anhydride with (aniline, triethylenetetramine and tetraethylenepentamine). The structures of prepared compounds were investigated using Fourier-transform infrared spectroscopy (FTIR). The different teroplymers were prepared by polymerization reaction of imides, different alkyl acrylate esters and olefins in different ratios. The molecular weights of all polymers were detected using gel permeation chromatography (GPC). The thermal stability of the prepared terpolymers was detected using thermo gravimetric analysis (TGA), it was found that the prepared terpolymers have high thermal stability. The degradation of the polymers was in the range between 325°C – 490°C. The rheology behavior shows that the viscosity of lube oil without any additives is approximately constant with increasing the shear rate. This indicates that pure lube oil behaves like a Newtonian fluid at any shear rate, but with additives it was found that at low shear rate the viscosity gradually decreases and the lubricant behaves like non-Newtonian fluid. However, at high shear rate viscosity of the lubricant approximately remain constant and behave like Newtonian fluid. It is noticed that the rate of decrease in viscosity by increasing shear rate reduces by decreasing the acrylate chain length in the terpolymer to approach the ideal Newtonian behavior in case of polymer (E1 and E2). The prepared terpolymers were evaluated as viscosity index improvers and pour point depressants. It was found that the viscosity index of lube oil increases with increasing the concentration of the additives. The viscosity index of the lube oil increases with increasing the chain length of alcohols till hexadecyl alcohol then it decreases when octadecyl alcohol is used. Using dodecene in terpolymer preparation gives better viscosity index results than other olefins. The viscosity index of lube oil increases with increasing number of nitrogen atoms in imide used in terpolymer. The viscosity index of oil is 140 in case of using polymer (E3), and succeeded in decreasing the pour point of oil to -24 in case of polymer (E2). It was found that the efficiency of the prepared additives as pour point depressants for lube oil increases with increasing the concentration of the prepared additives till 1% then it reduces. By using dodecyl acrylate in the terpolymers preparation, it give best result p.p (-21). There is no effect on p.p by changing olefin used in the polymer. By using aliphatic amine in preparation of imide, the results indicate that the efficiency increases with increasing the number of nitrogen atoms in imide. Neutral sulfurized calcium dodecyl phenate was prepared and evaluated as detergent/dispersant. It was found that it has high efficiency in reducing the sludge percentage to 0.04%. Zinc amylisobutyldithiophosphate was prepared and evaluated as oxidation inhibitor. The variation in total acid number reached (∆T.A.N = 0.54) at concentration of 0.5% additive. Two packages were prepared by using different prepared additives (viscosity index improver, pour point depressant, antioxidant and detergent/dispersant) and evaluated. It was found that one of these two packages has higher efficiency and can be used to improve and enhance the properties of lube oil.