Calorimetry for Inferential Conversion Monitoring in Emulsion Copolymerization Reactors

A dynamic model was developed describing emulsion copolymerization of styrene and MMA within a batch/semibatch stirred tank reactor. This model includes the initiation, propagation, transfer and termination steps of the monomers styrene and MMA. It also includes the mass and energy balance equations for the polymeric radicals. Energy balance equations incorporate the heat of reaction, internal and external heat transfer effects, as well as heat losses. The resulting sets of (differential/algebraic) equations were solved for both species concentrations and temperature profiles as functions of time. Experiments were conducted in a laboratory reactor, instrumented with platinum resistance thermal transducers and gravimetric conversion measurement devices. Thermal measurements in conjunction with the energy equations helped estimate monomer conversions as a function of time. The kinetic model predictions of conversion compared well with inferential calorimetric measurements, which were validated using gravimetric data. The experiments were run at variable operational conditions in terms of feed rate, temperature and monomers feed ratio. The calorimetric model was used as a soft sensor for the prediction of the rate of reaction, conversion and molar mass.