SIMULATION-MODEL FOR NETWORK FORMATION IN FREE-RADICAL CROSS-LINKING COPOLYMERIZATION - PREGELATION PERIOD

A new simulation model for network formation in free-radical copolymer ization of vinyl and divinyl monomers is proposed. This model is based on the crosslinking density distribution of the primary polymer molec ules that results from a kinetically controlled network formation. The crosslinking density distribution provides information on how each ch ain is connected to other chains and, therefore, a detailed analysis o f the kinetics of network formation becomes possible by application of Monte Carlo simulations. In this method, not only averages but also v arious distributions, such as molecular weight distribution and distri bution of crosslinked units as well as of unreacted pendant double bon ds among various polymer molecules, can be calculated. The present the ory is a direct solution for the Bethe lattice formed under nonequilib rium conditions, and, therefore, it can be used to examine the applica bility of the earlier theories of network formation to kinetically con trolled systems. The present method is quite general and can be applie d to various complex reaction systems that involve crosslinking, branc hing, cyclization and degradation in a nonequilibrium system.