A simulation for the bulk polymerization of acrylonitrile

In this paper, referring to the experimental observation of Thomas and Pellon, the authors consider the possible features of the development of the inter- and intra-molecular forces of polymer and monomer molecules in the reaction mixture. Then, a critical chain length is proposed to be a criterion for the loci of polymerization for the polymer molecules. The polymer molecules formed initially exist and react in the solution phase. As soon as they attain a chain length longer than the critical chain length, they will separate from the solution phase, and continue their reaction in the precipitation phase by the diffusion-controlled process. The chain transfer to monomer reaction is suggested as the deactivation reaction for the precipitated polymer radicals. In the kinetic treatment, the unsteady- state condition is applied for the precipitation phase, while the steady-state assumption is used for the solution phase. Using the kinetic model proposed above, the authors provide the kinetic parameters for this acrylonitrile polymerization. The simulations of conversion-time, rate-conversion, and molecular weight- conversion obtained fit excellently with the data of Hamielec et al. The critical chain length for this acrylonitrile system is found to be a function of the reaction temperature and the conversion.