Abstract
<p>Low-density polyethylene (LDPE) is a very important material for the manufacture of engineering and commodity plastics. The products are usually produced in high-pressure free radical polymerization either by autoclave or by tubular processes. This study presents a kinetic model based on a postulated reaction mechanism to describe the evolution of monomer, initiator consumption and the average molecular weights of ethylene polymerization in a high-pressure polymerization tubular reactor. The variations in the density and viscosity of the reacting mixture along multiple injection points for an initiator are used along reactor length is explicitly taken into account. A simulation program is developed to solve the mathematical model and the results are compared with those reported earlier. Further, the optimal control of the LDPE reactor is carried out using genetic algorithms to maximize monomer conversion using the jacket temperature of heat-exchange fluid as a control function along reactor length. The results indieate a 22-40% increase in the reduction of monomer concentration.</p>
Highlights
1.1 Objective o f this workThe objective of this work is to review the mechanism of polymerization reaction, develop mathematic models for initiator, monomer, radicals and polymers after exploring industrial and literature data, and studying the operation parameters and kinetics from earlier reports
The model is based on hypotheses of plug flow, steady state and homogeneous reaction mixture with prediction of thermodynamic and transport properties along the axial coordinate
This model accounts for most of reactions reported by different investigators, such as peroxide initiation, thermal initiation, combination, disproportionation, transfer to monomer, transfer to polymer, transfer to product modifier, y9-scission of terminal radicals, y9-scission of backbone radicals, and backbiting
Summary
The objective of this work is to review the mechanism of polymerization reaction, develop mathematic models for initiator, monomer, radicals and polymers after exploring industrial and literature data, and studying the operation parameters and kinetics from earlier reports. The simulation results are to be given based on proposed model using a self-developed program. The author has written the reaction mechanism for initiation, propagation &nd termination of the reactions, and developed the mathematical model of kinetic tubular reactor, live radical and dead polymer. A self-developed program is used to simulate the mathematical model and optimize operating conditions. It follows by the conclusion remarks and suggestions for future work
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