FTIR analysis of thermally processed PU foam

The chemical composition, density, and modulus of PU foam was examined as a function of processing temperature (25 °C, 45 °C, and 85 °C). Degradation of uretoneimine cross-links and the emergence of carbodiimide functional groups are monitored and the remaining composition in the PU foam is determined using FTIR spectroscopy. The density and modulus of the PU foams after thermal processing are measured and discussed with respect to the change in chemical composition of the materials. The data indicates that the composition of chemical cross-links, the density, and the modulus all decrease as a function of increasing processing temperature. The modulus of the PU foam shows a linear dependence of the processing temperature decreasing by 20% at the highest temperature. The results suggest that processing temperature may be used to target defined physical and mechanical properties of PU foams without changing the composition of reactants used.