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SYNOPSISN-Alkyl acrylatecl and n-alkyl methacrylates were prepared by esterification of acrylic and methacrylic acids with two long-chain alcohol blends NAFOL 2022 and NAFOL 1822. The prepared monomers were characterized and polymerized individually. In addition, copolymers of n -alkyl acrylate-n-alkyl methacrylate, and n -alkyl methacrylate-vinyl acetate and a terpolymer of n-alkyl acrylate-acrylic acid-vinyl acetate were also synthesid These polymers were also characterized and then evaluated as flow improvers in Khalda mixtureand S a l m Egyptian waxy crudes. The majority of the prepared additives showed good performance in improving the flow properties of the tested crudes. 0 1994

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LOW TEMPERATURE RHEOLOGICAL BEHAVIOR OF UMBARKA WAXY CRUDE AND INFLUENCE OF FLOW IMPROVERThe low temperature flow properties; pour point and rheological parameters; have been determined for untreated and additive treated Umbarka waxy crude. The rheological characteristics of the crude showed non-Newtonian yield pseudoplastic flow behavior and pronounced thixotropic effect. Viscometric data are fitted to Bingham, Casson and Herschel-Bulkley plastic flow models using linear and non-linear computer regression analysis. Herschel parameters showed inconsistent results whereas Casson equation fitted the data reasonably well. Treatment of the crude with flow improver ameliorated both rheological properties and pour point but in a different manner. The influence of the additive on the rheology of the crude is greatly affected by shear rate. The thixotropic phenomenon of the crude is likely to be temperaturedependent in addition to the other controlling factors. El objeto de este estudio consiste en determinar las características del crudo parafínico de Umbarka, con o sin aditivos para la mejora de la fluencia, así como los datos reológicos. Las características reológicas del crudo presentan un comportamiento de fluencia seudoplástica, con un límite elástico no newtoniano, así como un efecto tixotrópico acusado. Se ha establecido una correlación entre los datos viscométricos y los modelos de fluencia plástica de Bingham, Casson y Herschel-Bulkley, utilizando para ello un análisis de regresión informática lineal y no lineal. Si bien los parámetros de Herschel dan lugar a resultados incoherentes, en cambio, la ecuación de Casson permite establecer una correlación razonablemente satisfactoria de los datos. El tratamiento del crudo por medio de un aditivo de mejora de la fluencia tiene repercusiones positivas, aun cuando diferentes, acerca de las propiedades reológicas y el punto de fluidez. Los efectos del aditivo sobre la reología del crudo dependen ampliamente de la relación del esfuerzo cortante y es probable que el fenómeno tixotrópico dependa de la temperatura, además de los otros factores determinantes.