Optimization of Synthesis of Expandable Polystyrene by Multi-Stage Initiator Dosing

Suspension polymerization process is commonly used to produce expandable polystyrene. In the conventional method for producing this polymer, two different initiators are added to the process at two different temperature levels. In the industrial scale, this process is time consuming and difficult to control. A new method (Multi-Stage Initiator Dosing, MID) is proposed in which the initiator is dosed into the reactor. Laboratory and bench scale tests of this new method result in better control of the process, shorter reaction times and better quality of the product. Optimum temperature and dosing intervals are determined. The properties of the prepared samples by MID and conventional methods are compared with each other. According to the results, time process and consuming amount of initiator is reduced. Also, absorption of pentane was evaluated comparison to conventional methods. In fact, in this process the suspension control would be easier due to varying dose of initiator in several stages.