Experimental studies and mathematical modeling of aqueous suspension polymerization reactors.

摘要

Modeling and simulations of free radical polymerizations in different processes (bulk, solution, suspension, emulsion, dispersion) should not require altered sets of kinetic rate constants for the same monomer or monomer mixture system. Appropriate handling of the different physical picture in each process and an accurate description of all the elemental steps (physical and chemical phenomena) can result in universal models built on the common kinetic mechanism of free radical polymerizations.;Detailed computer programs for the simulation of bulk, solution, and suspension free radical polymerization stirred tank reactors were developed within the POLYRED package framework. With the addition of models for mixers, and splitters/separators the dynamics of any process flowsheet can be studied. Our homogeneous free radical polymerization models have been extended to consider suspension polymerizations of partially water soluble monomers. Simulation results from these models are compared to experimental results from the literature and from our own suspension polymerization experiments showing good agreement.;Results from our experimental studies of aqueous suspension homo- and copolymerizations are presented. Measurements include conversion profiles, chain length distributions, droplet size and final particle size distributions. Simulation results from our free-radical polymerization kinetics models, using established physical and kinetic parameter values from the bulk and solution polymerization literature were found in good agreement with the batch suspension experimental results.;A continuous process for suspension polymerization was designed and tested experimentally. The setup consists from a bulk prepolymerization step, a static mixer for the dispersion of the viscous prepolymer in the aqueous phase, and two suspension stirred tank reactors in series.;Liquid-liquid dispersion phenomena were studied experimentally during our suspension polymerization experiments by following the time evolution of the droplet size distribution (DSD) and by measuring the final particle size distribution (PSD). A computer model for the prediction of the DSD evolution was developed based on the discretized form of the population balance equation for the droplets in a stirred tank.