Bulk polymerization of acrylonitrile

Abstract The paper relates to topochemical and kinetic aspects of the bulk polymerization of acrylonitrile (AN). The very limited solubility of PAN in AN and the glassy state of the polymer phase result in the fact that it is only on the surface of polymer phase particles that chain propagation and termination can take place. The high porosity of polymer phase structural formations makes for physical isolation of macroradicals and of the initiator itself during polymerization in view of the closing of pores by the polymeric component. Quantitative kinetic equations have been derived which satisfactorily describe extremal type relationships (the presence of a maximum) appearing on the kinetic curves and reflect the competition between two opposite processes: on the one hand the number of radicals increases, and on the other hand physical isolation of the initiator is observed. The data published in literature are critically analyzed.