Hazards of radical polymerizations: Thermokinetic investigation of styrenepolymerization methods

Radical polymerization methods are prone to runaway under extreme process c onditions. A review of case histories of polymerization incidents indicate that human error coupled with equipment failures,loss of cooling, temperatu re control and mischarging of reactants are the primary cause for triggerin g runaway accidents, Many of these accidents can be reduced or eliminated b y changing the materials, alternative synthetic chemistry routes and proces s variables. Runaway hazard evaluation is the principle approach to assess and eliminate the inherent hazards. In this paper, hazard characterization of bulk and suspension methods of styrene polymerization, by microcalorimet ric techniques is studied. The investigation indicates that suspension poly merization of styrene is less hazardous than the bulk polymerization method . The kinetics autocatalytic nature of suspension polymerization is present ed. The coolant requirements for safe operation, as well as the temperature shoot up profiles for its failure for a typical 4000-kg batch commercial s tyrene polymerization reactor is simulated by employing reaction calorimetr ic data. ARC study indicates that a large excess of water present in the re action mixture acts as a thermal sink and rules out the possibility of seve re thermal hazards.