Understanding Vinyl Acetate Polymerization Accidents

• Published in: Organic process research & development Vol. 9; no. 6; pp. 962 - 975
• Main Authors: Gustin, Jean-Louis, Laganier, Franck
• Format: Journal Article
• Language: English
• Published: American Chemical Society 01-11-2005
• ISSN: 1083-6160; 1520-586X
• DOI: 10.1021/op050097f

Vinyl acetate is processed to produce polymers and copolymers used in water based paints, adhesives, paper coatings or nonwoven binders and various applications at moderate temperatures. The polymerization processes used include solution, suspension and emulsion processes. Many incidents involving the runaway polymerization of vinyl acetate monomers (VAM) are known. In processes where the polymerization initiator was dissolved in the monomer, the initiator premix polymerized violently in the premix vessel. In polymerization processes where vinyl acetate monomer conversion ratio was not 100%, storages of recycled monomers containing no polymerization inhibitor and possibly some traces of polymerization initiator exploded due to VAM violent bulk polymerization. Incidents happened either in batch or semi-batch polymerization processes in connection with wrong catalyst introduction. In this paper, a review of polymerization incidents is given. Radical chain polymerization kinetics are used to explain some accident features such as polymerization isothermal induction periods. Experimental results on bulk VAM polymerization obtained in DSC, Dewar flask, and VSP are given. The accidental polymerization of VAM in a vessel is simulated using the WIN SIM software. The simulation is based on radical chain polymerization kinetics and thermochemical data on VAM and polymers and on specified initial and boundary conditions. Simulation of accidental polymerizations is useful to validate accident scenarios and evaluate various cause hypotheses.