Forced Oscillations in Continuous Polymerization Reactors and Molecular Weight Distribution Control. A Survey

MEIRA, G. R.

Journal of Macromolecular Science Revs In Macromolecular Chemistry

Año: 1981 vol. C20 p. 207 - 241

It is shown that an extended flexibility in the MWD control in polymers can be obtained when a continuous polymerization reactor is operated under forced oscillations rather than the SS. Furthermore, periodic operation not only can be beneficial from the point of view of the quality of the product but can also be an excellent means of controlling, for example, the reaction temperature in a metastable region as with "bang-bang" radiation control. In free radical polymerizations the oscillation of the monomer and the initiator around the SS proved to have only a very small effect on polydispersity; however, greater effects were verified when pulsing a transfer agent. The oscillation of this parameter also had a relatively great effect in Ziegler-catalyzed polymerizations. Results indicate that for a particular mechanism, when the reactor type is sought to produce the narrowest possible MWD in the SS, the effect of periodic operation seems to invariably be that of broadening it. If, however, the reactor type is not optimal in the sense of a narrow distribution, then narrowings in the MWD can be produced.