Modelling of a continuous kneader reactor for the polymerization of partially neutralized acrylic acid

A mathematical model and analysis of the continuous polymerization of partially neutralized acrylic acid (AA) in a continuous kneader reactor is presented here as an initial attempt to simulate the synthesis of a superabsorbent polymer. A detailed kinetic model has been used to describe the copolymerization of AA and sodium acrylate (NaA) in aqueous medium. This model is used to describe batch and continuous operations. The polymerization is initiated by a mixture of potassium persulphate (K2S2O8, KPS) and hydrogen peroxide (H2O2) as oxidizing agent and ascorbic acid (AsA) as reducing agent. A novel set of kinetic parameters has been estimated by fitting experimental data from different literature sources. The operation of a continuous kneader reactor modelled as a plug-flow reactor with axial dispersion is theoretically investigated to predict temperature profile, total and individual monomer conversion, consumption of KPS, H2O2, and AsA, and polymer average molecular weights. The simulation results show the presence of a hot spot close to the reactor entrance that could be potentially severe during startup and could have a detrimental impact on polymer quality. This model is a first step in the direction of achieving optimal operating protocols and exploring improved polymerization reactor designs.

Automated summary

This study presents a mathematical model and analysis for the continuous polymerization of partially neutralized acrylic acid. The copolymerization of acrylic acid and sodium acrylate in an aqueous medium is described using a detailed kinetic model. The operation of a continuous kneader reactor is theoretically investigated to predict various parameters such as temperature profile and monomer conversion. This model serves as a starting point for optimizing operating protocols and improving polymerization reactor designs.