KINETICS OF NETWORK FORMATION IN FREE-RADICAL CROSS-LINKING COPOLYMERIZATION

A new kinetic theory for network formation in free-radical copolymerization of vinyl and divinyl monomers is used to investigate various important property changes in the postgelation period, such as the weight fraction of gel, the molecular weight distribution, the cross-linking density within sol and gel fractions, the partition of the unreacted pendant double bonds between sol and gel, etc. This theory is based on the cross-linking density distribution among primary polymer molecules, and the history of the generated network structure is fully accounted for. It is shown clearly that the deviation from the Flory-Stockmayer theory becomes significant as the variance of the cross-linking density distribution increases. The present simulation model is quite general and can be applied to various complex polymerization systems that involve cross-linking and branching in a kinetically controlled system irrespective of the reactor types used.