Modeling and optimization of suspension SAN polymerization re actors

A detailed mathematical model is developed to describe the operation of batch-modified SAN [styrene (ST)/acrylonitrile (AN)/α-methylstyrene (AMS)] terpolymerization reactors. The model is validated by comparing simulation results with published and plant experimental data. Optimal temperature policies and initiator feed concentrations are then computed. It is shown that optimal operation conditions may be extremely sensitive to small perturbations, so that optimal operation conditions may actually be unfeasible. It is also shown that average polymer molecular weight may be properly controlled by adding small amounts of inhibitor into the polymerization medium, which is usually cheaper than using chain transfer agents to control the average polymer molecular weight.