Molecular-weight distribution attainable in a batch free-radical polymerization

The attainable values of molecular-weight distribution (MWD) specified by d ie degree of polymerization and the polydispersity ill a batch free-radical polymerization reactor are described. The two-step method based on the qua dratic profile of die instantaneous degree of polymerization is used to obt ain die recipe producing the polymer with the desired MWD specification. Th e analytic solution for the quadratic profile is derived and analyzed in or der to estimate the attainable MWD given the constraints on the range of th e instantaneous degree of polymerization The entire computational procedure is intelligently organized, and thus die actual computational load is very low compared to the conventional optimization scheme. The MWD attainable u nder a specific operating condition with constraints in a batch styrene pol ymerization reactor is visualized and various reactor temperature trajector ies that would produce the desired polymer product are calculated. The abil ity to predict the attainable MWD allows ail engineer to easily design the recipes that would meet the desired MWD specification.