Free-radical polymerization of methacrylic acid: From batch to continuous using a stirred tank reactor

In the last years important efforts have been made to convert the traditional batch polymer production to continuous. This transition allows to overcome most of the limitations of discontinuous or semi-continuous processes, such as environmental and safety issues and inadequate product quality. In this work we propose a model–based strategy to convert the solution free-radical polymerization of non-ionized methacrylic acid (MAA) from semibatch to continuous while preserving the product average molecular weight and polymer content. First, a purely kinetic model for the polymerization of MAA was validated for batch, semibatch and continuous stirred tank reactors (CSTR). Then, a basic optimization approach was applied to guide the transition of a selected semibatch process to a CSTR. This strategy results in a substantial productivity increase (5.1 times higher than in the original semibatch) while preserving the selected polymer average molecular weight and dry content. Finally, in order to reduce the residual monomer in the product leaving the CSTR, we simulated the addition of a tubular reactor. This was modelled introducing a small plug flow reactor in series to the CSTR. This approach represents an effective and robust tool for polymer manufacturers to assist switching their productions to continuous preserving their product portfolio.