Reactor dynamics and molecular weight distributions: Some aspects of continuous polymerisation in tubular reactors

A study was made of the effect of residence time distribution and thermal nonuniformities on molecular weight dispersion in continuous nonchain and chain polymerizations, respectively. The analyses were conducted with the aid of the assumption of microsegregation, which facilitated and unified the computational approach. Holdback was examined and found to be a good criterion for characterizing the importance of residence time distribution. Power‐law flow index was found to have a direct effect on molecular weight dispersion in isothermal nonchain polymerizations as well as an indirect influence in chain polymerizations via its role as a parameter for thermal sensitivity. It was concluded that the isothermal, segregated, continuous stirred tank reactor has a greater effect on molecular dispersion in nonchain‐type polymerizations than the worst isothermal tubular reactor, as correctly predicted by holdback, and temperature nonuniformities have a profound influence on molecular dispersion in chain‐type polymerizations.