Modelling of phenol—formaldehyde polymerization reaction

In the condensation polymerization of phenol and formaldehyde, the ortho and para positions exhibit different reactivities. In addition, along a polymer chain, internal reactive sites have lower reactivity, possibly due to shielding phenomena^1,2. A detailed kinetic model for novalac formation has been proposed accounting for all these factors. Five different kinds of reactive sites have been shown to exist on a polymer chain and the reactivity of a given reaction has been assumed to be governed completely by the reactive site involved in it. A mass balance has been written for each site and the equations have been solved numerically to examine the effect of different parameters on the course of the condensation polymerization. The model predicts polymer chains with small levels of branching, which is consistent with experimental observations.