Studies on synthesis of oligomeric urethane prepolymers as intermediates to make linear pulyurethanes

Polyaddition carried out at various mole ratios of tolyl diisocyanate and di- or trifunctional polyetherols gave urethane oligomers containing isocyanate or hydroxy groups as terminal groups (Tables 1, 2). The chemical structure of the products was studied by IR, H-1-NMR and GPC (Figs. 1-5, Table 3). The oligomers were used to prepare cast PUR and their mechanical and thermal property data were determined (Table 5). Trials were made to correlate the chemical composition of the resulting oligomers and their M and MWD with those expected from the stoichiometry of the reaction and calculated by the REAKTOR program that simulates nonequilibrium linear polyaddition of diisocyanate (Table 4, Figs. 6-8) and polyol. The usefulness of the analytical methods used and of the numerical simulation applied is discussed for the technology of making urethanes.