In situ Foaming Evolution of Flexible Polyurethane Foam Nanocomposites

The effect of both as-produced and functionalised CNTs on the polymerisation evolution of water-blown PU foams containing up to 0.3 wt.-% CNTs was studied by in situ FT-IR spectroscopy. FT-IR revealed a decrease on the rate of isocyanate conversion as a function of loading fraction for both as-grown and oxidised CNTs. This dependency suggested that the isocyanate conversion at the early stages of the reaction was governed by the kinetic effects imposed by the presence of the CNTs. The onset of microphase separation was accelerated by the addition of functionalised CNTs (f-CNTs) but not by as-produced CNTs due to the different surface functionalities. Measurements of the foaming viscoelastic properties showed an increase on the storage modulus with the CNT content, which indicated the reinforcement of the foam.