Step polymerisation with unequal reactivities in a CSTR

Abstract

A mathematical model for step polymerisation of BB with AA in a CSTR where the functional groups of AA are not equally reactive has been developed. Unequal reactivity can be due to either asymmetry or induced asymmetry. The polydispersity index (PDI) of the product of a CSTR was calculated and was found to be always greater than that of a batch reactor. Calculations show that, when compared with situations where unequal reactivity is absent, the presence of induced asymmetry can cause either an increase or a decrease in PDI while the presence of asymmetry can only cause a decrease in PDI. However where BB is in excess of AA in the feed, the limit of the calculated PDI as residence time tends to infinity was unaffected by unequal reactivity.