Novel phenomenon of autoacceleration in the free radical oxidative polymerization of vinyl monomers: a thermochemical approach

A unique phenomenon of 'autoacceleration' was observed in a free radical po lymerization of vinyl monomers and oxygen. Unlike the well known autoaccele ration phenomenon in polymerization processes, this unusual phenomenon is n ot readily conceivable in terms of solution viscosity based reasoning. Surp risingly, we have observed manifestation of this new autoacceleration durin g free radical oxidative polymerization of some vinyl monomers at low conve rsions, where generally the polymerization reaction is zero order, the conv ersion-time plot are linear and viscosity effects are negligible. In the pr esent paper, we interpret the mechanism of this new autoacceleration phenom enon on the basis of reactivity of the propagating radicals in terms of hea t of formation data. (C) 2001 Elsevier Science Ltd. All rights reserved.