الفهرس 
Chapter (I) 1. IntroductionOnly 14 pages are availabe for public view
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Abstract
Viscosity measures the internal friction within a liquid, reflecting the way that the molecules interact to resist motion. It is a vital lubricant property, influencing the ability of the oil to form a lubricating film or to minimize friction which leads to reducing wear.
The viscosity index of a fluid refers to the ability of a fluid to maintain viscosity and lubricity over a specified temperature range, most often between 40 °C and 100 °C. The viscosity index (VI) is the most frequently used method for comparing the variation of viscosity with temperature for different oils. The aim of this work was to synthesize and characterize some polymeric materials as viscosity index improvers for lubricating oils.
Four alkyl oleates (ESO, ESI, ES2, and ES3), as a starting compounds, were prepared using oleic acid and four fatty alcohols. Four copolymers (CO-0, CO-1, CO-2, and CO-3) were prepared using these alkyl oleates and maleic anhydride. Diesters of CO-1, CO-2 or CO- 3 with three fatty alcohols were prepared. Copolymers (CO-4, CO-5 and CO-6) were prepared using styrene and alkyl oleates (ESI, ES2 and ES3). Terpolymer (CO-7) was prepared by polymerization of maleic anhydride, oleic acid, and styrene. While the terpolymer was esterified by 1-octadecanol to obtain CO-7-C18.
All the prepared copolymers, esters and the commercial viscosity index improver C.P were characterized by (FTIR) and tested as a viscosity index improvers for lubricating oils. These tests were carried out according to ASTM D 445. The copolymers (CO-1, CO-2, CO-3 and C.P) were evaluated as a viscosity index improvers for multigrades lubricating oils. Three multigrades formula 5W/30, 15W/40 or 20W/50 was blended using different wt percents of every copolymer with base oils and additives. The shear stability tests were carried out for 20W/50 grades formulas to check the stability of polymers as viscosity index improver applications at high temperatures. Also TGA, XRD, and GPC were carried out for these three copolymers and C.P.
ES2 (octadecanol oleate or stearyl oleate) revealed a little improvement of BO.l viscosity index than other oleate compounds.The effect of the alkyl oleates on the viscosity index of BO-1 was ranked in the order ES2 (C18) > ESI (C16) > ES3 (C20 branched)>ES0 (C6).
The effect of the used polymers as viscosity index improvers was ranked in the order: C.P> CO-2 > CO-1 > CO-3 > CO-7 > CO-5 > CO-4 > CO-6 > CO-O The commercial polymer (C.P) had higher molecular weight than the prepared copolymers, so its effect as a viscosity improver for BO-1 was higher than all the used copolymers.
The efficiency of polymeric esters as a viscosity improvers was less than the prepared polymers due to the absence of maleic anhydride by esterification reaction. The results showed that octadecanol maleic anhydride copolymer ester (CO-2-C-18) was more effective as a viscosity index improver than other esters.