Speeding Up the Rate of Polystyrene Production Using Acid Mediation

3 SPEEDING UP THE RATE OF POLYSTYRENE PRODUCTION USING ACID MEDIATION 

A very unique approach to increasing the production rate of high MW polystyrene was recently developed by Dow researchers. They discovered that the rate-MW curve for auto-initiation polymerization of styrene can be significantly 

To understand this effect requires a discussion of the mechanism of autoinitiation. Of the mechanisms proposed, two receive most of the discussion in the literature. A mechanism proposed by Flory [15] involves a 1,4-cyclobutane diradical intermediate and has been supported experimentally by polymerization in the presence of a free radical scavenger. Several of the dimers found in thermally initiated polystyrene are also attributed to a Flory initiation mechanism. 

The aromatization reaction in this case is an example of homogeneous catalysis. The catalyst, reactant, and product are all dissolved in liquid styrene monomer. As such, traditional heterogenous catalysis considerations such as 

The solubility characteristics of the acid are also important. Acids that are insoluble in styrene would have difficulty contacting the DH dimer to catalyze the aromatization reaction. Acids that are slow to go into solution could cause practical problems for the design and operation of the process. For their study, the authors chose only acids that readily dissolved in styrene. 

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