Real time monitoring of the quiescent suspension polymerization of vinyl chloride in microreactors – Part 2. A kinetic study by Raman spectroscopy and evolution of droplet size

Abstract

This paper regards the experimental study on the polymerization of vinyl chloride droplets in quiescent state using microreactors. As presented in a previous work performed with methyl methacrylate monomer, this work presents results on the reaction kinetics of vinyl chloride (VCM) polymerization monitored by Raman spectroscopy and on the evolution of VCM droplets as captured by charge-coupled device (CCD) camera in a microcapillary. Different experimental recipes were proposed using commercial initiators in order to compare the system performance when initiated with monofunctional and bifunctional peroxides. For the first time in the open literature the evolution of VCM droplets is shown up to high conversions (>90%) in quiescent state. It is also shown how the pressure drop can modify the PVC particle morphology at the end of polymerization. Finally, it is shown that the Raman technique is able to monitor the reaction kinetics at different conditions, being possible to identify four different characteristic stages during the vinyl chloride polymerization reactions.