Based on free volume and chemical reaction kinetic theories

a kinetic model of free radical polymerization including diffusion phenomena was established. Unsteady process-cage effect which could affect initiator efficiency

and mass centre translation diffusion

segment rearrangement diffusion and reaction diffusion of the radical were considered. The volume shrinkage and exceeding free volume were considered also. This model was applied to the simulation of styrene bulk polymerization and agreed well with the experimental result.