Cover: Different morphological aspects of poly(vinyl acetate) particles produced through suspension polymer-ization are shown. When produced by conventional free radical polymerization, final particles present an irregular oval morphological aspect, due to combination of the high shear rates and high reaction rates. When small amounts of the RAFT chain transfer agent are used, final particles present the usual spherical morphology of beads produced in suspension, due to the lower reaction rates and consequently longer relaxation times to dissipate shear tensions. Further details can be found in the article 453 Full Paper: Moving horizon estimation is an optimization-based filter that can address non-linear and constrained systems. A monitoring procedure with statistical parameters estimated by the autocovar-iance least-squares technique is proposed and validated with experimental emulsion polymerization reaction data. The estimation results are compared with gravimetric analysis and the effect of the initial estimate is also evaluated, showing that the procedure is robust.

Significant information about polymerization reactions carried out in lab‐scale reactors is lost because sampling is not always possible due to the high viscosity, heterogeneity of the reaction medium or pressurization of the reactor. Thus, monitoring these reactions through calorimetry technique could be very valuable. Nevertheless, standard lab‐scale reactors can present a relatively high residence time of the cooling fluid in the jacket and significant heat loss of the jacket to the surroundings. In the present work, the effect of the cooling fluid flow rate on the estimation of conversion through isothermal and isoperibolic calorimetry during a batch emulsion polymerization was investigated. Results show that the estimation of conversion through isothermal and isoperibolic calorimetry was not significantly affected by the cooling fluid flow rate using heat flow calorimetry. Nevertheless, when employing the energy balance of the jacket and the estimation of the global heat exchange coefficient between the jacket and the surroundings to estimate conversion (heat balance calorimetry) better results were obtained for lower cooling fluid flow rates.

Reaction calorimetry is a very useful tool to monitor exothermic polymerization reactions as it is based on the estimation of the heat generated by the reaction. The objective of this work is to analyze the performance of an unscented Kalman filter (UKF) for online monitoring of batch vinyl acetate emulsion polymerization reactions. Reactions are performed in isoperibolic and isothermal conditions. The UKF is compared to an extended Kalman filter that has a very poor performance. The results show that the UKF is able to provide good estimates for the conversion, for the reactor and jacket temperatures, for the overall heat transfer coefficient between the reaction medium and the jacket, and for the heat loss from the jacket to the surroundings. magnified image

In‐line monitoring of semi‐batch vinyl acetate emulsion polymerizations was performed combining heat flow and heat balance calorimetry to re‐estimate the overall heat transfer coefficient between the reactor and jacket. The initial UARJ was obtained applying a constant power through an electrical heater to the initial reactor charge. As UARJ changed during the reaction, it was re‐estimated combining the mass and energy balances of the jacket and the reactor and minimizing an objective function in terms of TJ_out. Results showed that good in‐line estimations of conversion can be performed without requiring the use of experimental conversion data to re‐estimate UARJ during the reaction.

Reaction calorimetry is a very useful tool for monitoring exothermic polymerization reactions as it uses the measurement of the liberated energy to calculate the reaction rates. Despite the estimation of conversion for homopolymerizations being well established for commercial calorimetry reactors or lab‐scale reactors specially constructed to operate as calorimetry reactors, it is still a challenge to use calorimetry to estimate conversion in standard lab‐scale reactors. In the present work, a standard lab‐scale jacketed stainless steel tank reactor with an internal volume of 5 liters was instrumented to operate as a calorimetric reactor. Water was used as the heating/cooling fluid and its flow rate was kept constant. The isothermal calorimetry and isoperibolic calorimetry were used to determine the conversion of batch vinyl acetate emulsion polymerization. Both results were compared and showed that, even at a relatively high residence time of the cooling fluid in the jacket (∼18 s) and significant heat loss, estimated conversions obtained by the measurements of reactor and jacket temperatures and by the mass and energy balances presented a good agreement with gravimetric data.