Frontal polymerization is a process in which a spatially localized reaction
zone propagates into a monomer converting it into a polymer. We formulate
a mathematical model of thermal free radical frontal polymerization involvi
ng a Eve-species reaction mechanism and justify its reduction to a four-spe
cies problem by combining the concentrations of two kinds of radicals, prim
ary radicals and polymer radicals. We study the simplified problem both num
erically and analytically, and determine such important characteristics of
the process as the propagation speed of the wave, the final temperature in
the System, and the spatial distributions of all the species in the wave. W
e perform the analyses with the steady-state approximation (SSA) and withou
t it, and reveal where the SSA solution breaks down. Specifically, the non-
SSA solution predicts full monomer conversion and an adiabatic final system
temperature, whereas the SSA solution predicts a less-than-adisbatic final
temperature and incomplete conversion. (C) 1999 Elsevier Science Ltd. All
rights reserved.