engleski

Optimization of Alkyl methacrylate solution terpolymerization process initiated by a bifunctional Diperoxide

Optimization of the alkyl methacrylate solution terpolymerization reactions and processes, initiated by a bifunctional free radical diperoxy initiator, as well as the properties of the obtained terpolymers as lubricating oil rheology modifiers have been described. The examined monomers were: methyl methacrylate, dodecyl methacrylate and octadecyl methacrylate. Polymerization reactions were performed in concentrated, 2 M base mineral oil solutions, under the isothermal conditions at 115 and 120 oC, using 1, 1-di(tert-butylperoxy)-3, 3, 5-trimethylcyclohexane bifunctional initiator. Terpolymers of different composition and molecular mass were obtained by varying the monomer mixture composition and concentrations of the initiator and chain transfer agent, n-dodecyl mercaptan. Low conversion terpolymerization kinetics was described by the Alfrey-Goldfinger equation ; terpolymer composition was calculated as a function of monomer feed composition as well as the curves of unique and binary azeotropy. The existence of the true ternary azeotropic point and a wide pseudo-azeotropic region were recognized, as a consequence of the similar values of copolymerization reactivity ratios of binary monomer pairs. It was demonstrated that very high overall reaction rates and high molecular mass terpolymers with narrow molecular mass distribution (MMD) could be achieved simultaneously by using bifunctional initiator. The reduction in polymerization cycle time of about 40 % was achieved at adequate polymerization temperature, in comparison to conventional processes with monofunctional initiators. The concentrations of molecular species and terpolymer structural parameters, like kinetic chain length, molecular mass averages and polydispersity index were calculated by a tendency kinetic model for radical polymerization, as functions of the reaction time. The rheological properties, such as kinematic viscosity, viscosity index and shear stability in base mineral oil solutions were determined experimentally and correlated to the polymer structural parameters. A strong correlation has been found between MMD parameters of synthesized polymers and rheological properties of polymer solutions.

Optimization; Terpolymerization; Alkyl Methacrylate; Bifunctional Peroxide; Additive

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