How to take the removal of condensation water into account in polyesterification kinetics?

In previous polyesterification reactions, the concentrations of reactants and catalyst (if present) were all expressed in moles per kilogram. In most cases, the progress of reaction was followed by the titration of acid groups. Consequently, the removal of condensation water is bound to affect the concentrations of reactants and catalyst. In this paper, a new general kinetic equation has been derived, which takes this effect due to the removal of condensation water into consideration more accurately. The unit of mol l(-1), who replaced the unit of mol kg(-1), is led into the calculation of acid concentration and the derivation of the general polyesterification kinetic equation for the first time. Its adoption can finally eliminate the error due to the change of the density of reaction system while adopting the unit of mol kg(-1).