A three parameter kinetic model of formation of linear polyurethane from 2,4‐toluenediisocyanate and butane‐1,4‐diol

A model of linear isothermal polymerization of two bi‐functional monomers, one of which has alike functional groups of different reactivities, is presented. The model has been applied to the polymerization of 2,4‐toluenediisocyanate (TDI)^a and butane‐1,4‐diol carried out in solution at 86 or 101°C. The rate constant K of the reaction between an isocyanate group in position 4 of TDI and a hydroxy group, the ratio κ of reactivities of groups in position 4 relative to that in position 2, and the ratio k_φ of reactivities of an isocyanate group in the monomer relative to that at the end of an oligomer chain, have been evaluated from experimental data to be 6.51·10^–4 dm³·mol^–1·s^–1, 1.47, and 1.55 at 86°C, and 17.2·10^–4 dm³·mol^–1·s^–1, 1.55, and 1.62 at 101°C, respectively.