Fabrication, synthesis and mechanical characterization of nanoparticles infused polyurethane foams

An innovative technique to develop polyurethane foams containing nanoparticles is introduced. Polymethylene polyphenylisocyanate (Part A) is mixed with nanoparticles such as SiC and Tio(2), and irradiated with a high power ultrasound liquid processor. In the next step, the modified foams containing nanoparticles are mixed with Part B (containing polyol resin systems, surfactant, and an amine catalyst) through a high-speed mechanical stirrer. The mixture is then cast into rectangular molds to make nanophased foam panels. Test coupons were later extracted from the panels to carry out morphological and mechanical characterizations. The as-prepared foams were characterized by scanning electron microscopy (SEM), X-ray diffraction, and thermo gravimetric analysis (TGA). The SEM studies have shown that the particles are in nanosize, non-agglomerated, and well dispersed in the entire volume of the foam. The foam cells are well ordered and uniform in size and shape. The TGA analyses indicate that the modified foams are thermally more stable than the parallel neat system. Quasi-static flexure tests under three-point bend configuration have also been conducted with both modified and neat foams. Test results show a significant increase (approximately in the range of 50-70%) in the flexural strength and stiffness of the nanophased foams over the neat system. This enhancement in flexural properties have been demonstrated repeatedly with multiple batches and with at least three specimens tested from each batch. Details of the fabrication procedure, synthesis, and characterization are presented in this paper. (C) 2003 Elsevier Ltd. All rights reserved.