الفهرس 
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Abstract
Flow characteristics of lubricating oil depend on viscosity but change viscosity with temperature affect on flow characteristics and flow rate depend on pour point of oil, but dissolved wax in oil begins to separate as crystals that interlock to form a rigid structure this leads to inhibits oil flow. Lubricating oil additives are chemical compounds added to the base oils to impart specific properties to the finished oils. Some additives used as improving performance additive especially viscosity index improvers and pour point depressants.
Viscosity is the most important physical property of lubricating oil; it is a measure of its internal friction or resistance to flow. In simple terms, it provides a measure of the thickness of lubricating oil at a given temperature; the higher the viscosity, the thicker the oil. The viscosity changes with temperature and varies inversely with temperature. Viscosity index improvers are normally high molecular linear polymers, and oil soluble polymers. The higher the viscosity index (VI), the less the viscosity of an oil changes for a given temperature change .Viscosity index improvers function by increasing the relative viscosity of oil more at high temperatures than at low temperatures. Generally the polymer changing its physical configuration with increasing temperature of the mixture. It is believed that the polymer molecule in solution exists as a random coil, which is swollen by the lube oil solvent. The volume of this molecule determines the viscosity increase. In cold oil the molecules of the polymer adopt a coiled form so that their effect on viscosity is minimized. In hot oil, the molecules tend to straighten out, and the interaction between these long molecules, having greater volume and the oil produces a proportionally greater thickening effect which in turn raises the VI of the oil.
Summary
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The pour point of lubricating oil is the lowest temperature at which the oil will pour or flow without disturbance under prescribed conditions. Most oils contain some dissolved wax which begins to separate as crystals that interlock to form a rigid structure. It has been suggested that it is more logical to add a pour point depressant. Pour point depressants are high molecular weight polymers that function by inhibiting the formation of a wax crystal structure that would prevent oil flow at low temperature. These additives do not entirely prevent wax crystal growth, but rather lower the temperature at which a rigid structure is formed. Pour point depressants act through surface adsorption on the wax crystals. The resulting surface layer of pour point depressant inhibits the growth of the wax crystals and their capacity to adsorb oil and form gels. In the absence of long interlocking crystals or swollen particles, oil can move freely through any solid wax particles that are present.
In the present work seven different esters were prepared via esterification of acrylic acid with seven different alcohols, (octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl and docosyl ). The prepared esters were determined by using Fourier Transform Infrared Spectroscopy (F.T.I.R), and determination of molecular weight using vapour pressure osometer .Then twenty–one terpolymers were synthesized via free radical chain addition polymerization of alkylacrylate (octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl and docosyl) acrylate, different α- olefins (dodecene, tetradecene and hexadecane ), and vinyl actate with different molar ratios. The structures of the prepared terpolymers were confirmed by using Fourier Transform Infrared Spectroscopy (F.T.I.R), Proton Nuclear Magnetic Resonance (1H-NMR) , determination of molecular weight using Gel Permeation Chromatography (GPC), thermal analysis (TGA) and showing wax crystallization behavior of the untreated
Summary
XII
and treated lube oil sample with terpolymer at different concentrations by Photomicrographic analysis using An Olympus Polarizing Microscope.
The prepared terpolymers were evaluated as lube oil additives (viscosity index improver, and pour point depressant). It was found that the viscosity index of prepared terpolymer increases with increasing the concentration of the prepared compounds and increases with increasing the alkyl chain length of the alkylacrylate used from octylacrylate till tetradecylacrylate, then a noticeable decrease occur in the viscosity index with increasing the alkyl chain length for hexadecylacrylate and octadecylacrylate, on contrary docosylacrylate had a bad effect on viscosity index. This may be due to the influence of the molecular weight on the effective coil radius and hence the VI. It was found that terpolymers prepared from tetradecene have a great effect as viscosity index improvers than dodecene and hexadecene terpolymers. This may be due to the effect of molecular weight
It was found that the prepared compounds are efficient as pour point depressants and the efficiency increases by decreasing concentration of the prepared additive, the additives depend on dodecylacrylate own the best efficiency as pour point depressants.