Stationary and non‐stationary processes in non‐classical radical polymerization with size dependent termination

Abstract

AbstractKinetic analysis of non‐classical radical polymerization is discussed in terms of the Group‐Termination Procedure on the basis of the geometric mean approximation. Expressions for important kinetic functions of stationary reactions, with or without chain‐transfer, are listed and compared with their classical counterparts. In the treatment of non‐stationary reactions (with or without transfer) special attention is paid to the calculation of pre‐ and after‐effects and their applications in the evaluation of absolute rate coefficients.Nomenclature: I = rate of chain initiation. R·r = concentration of radicals of size r. R· = total concentration of radicals = ΣR· r̄ = number‐average radical size.v = mean kinetic chain‐lengthτ = mean lifetime of a kinetic chain.ω = rate of polymerization (‐dM/dt).Subscripts 1,2 applied to the above signify values at the beginning or end, respectively, of a non‐stationary period.kfL = rate coefficient for chain‐transfer to species L l = kfLL/kpMV = j/kpM + lRa = (jk)½/(kpM); b = a/(1+l).magnified imageTo simplify the presentation concentration brackets are omitted. Conventional mol, dm3, s units are assumed throughout.