Improvement of nanoclays dispersion through microwaves processing in Polyurethane RigidNanocomposite Foams

Polyurethane rigid nanocomposite foams were synthesized by in situ-polymerization using both pristine and organically modified layered silicates. The effect of synthesis conditions, in particular the effect of different dispersing techniques, on morphology and mechanical properties of polyurethane nanocomposite foams was studied. To promote dispersion, clays were dispersed either in polyols or isocyanate and were subjected to a well known dispersion method, like ultrasonication, but also to a new dispersion method, based on microwaving. The morphological characterization of the foams, carried on using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, proved that the technology based on microwave processing is able to provide very good silicates dispersion and requires very short application time to be effective. Further confirmations of the importance of the clay organo-modifier are still present. Mechanical characterization of foams show that clay interferes with H-bond formation and then the overall compressive performance of PU nanocomposite foams depends on the competition between the positive reinforcing effect of clay and the negative effect on H-bond formation.