Vinyl chloride polymerization in microdroplet reactor

Abstract

Vinyl chloride suspension polymerization is a common reaction in polymer industry allowing to obtain one of the world wide most used plastics, known as PVC (polyvinyl chloride). Its applications involve mostly the construction industry but other domains are also concerned. This polymerization process is highly complex due to the toxic nature of the monomer, the good manage of heat transfer and agitation. The control of these process variables directly impacts the characteristics of the final product. Even though the suspension polymerization of vinyl chloride has been extensively studied in batch reactors, there is a lack of data regarding the kinetics or the physicochemistry of a single monomer droplet during the reactions. The aim of this present work is to propose a microstructured device which enables obtaining monodisperse droplets within 200 µm in diameter, each one being considered as a polymerization reactor. After a good acknowledgement of the vinyl chloride/water system in microchannel the polymerization reaction was qualitatively described by means of droplet/polymer grain visualization. Real-time non-invasive Raman measurement has been performed on stationary vinyl chloride monomer droplets and has provided values of kinetic constants. A theoretical model was proposed, simulating the reaction conversion in good agreement with the experimental values. The morphologic characteristics of the PVC grains obtained in microreactor presented interesting features in terms of primary particle agglomeration or porosity.