Modeling of polymerization of urea and formaldehyde using functional group approach

Abstract

SynopsisThe urea formaldehyde polymerization has been modeled using the functional group approach, which accounts for the formation of higher oligomers. The kinetic model involves four molecular species and three rate constants, as opposed to six as proposed in earlier studies. The experimental data of Price et al. have been curve fitted using our model, which is found to describe them very well in the entire range of temperature and urea formaldehyde ratio. Based on the activation energies, it has been argued that the reverse reaction step must involve the condensation product, water.

A very simple empirical kinetic model of the acid‐catalyzed cure of urea–formaldehyde resins

“…This matter needs to be solved, because higher initial concentrations of formaldehyde are nowadays often used. Mejdell and Schønsby 19 have slightly extended the Kumar-Sood model 21 now including condensation reactions and achieved a good agreement with their limited experimental data, but it should be noticed that their rate equations in terms of functional groups do not reflect the correct situation concerning the reverse reactions. A slightly more consistent model has been proposed by Costa and Bachmann, 22 but as it is discussed in that same reference, it only takes into account FSSE effects.…”

“…Kumar and Sood 21 have put forward a FSSE model for the early stage of the UF condensation process and have been able to fit the data of Price et al 18 assuming the hydrolysis reactions to be bimolecular. Both de Jong and de Jong 16 and Price et al 18 have considered them to be unimolecular.…”

Polycondensation

“…Kumar and Sood [208] have considered it could be bimolecular, which seems to be reasonable. Kumar and Sood [208] have considered it could be bimolecular, which seems to be reasonable.…”