Authors: J.L. Stanford, P.A. Cookson, N.H. Fithriyah, A.N. Wilkinson
Affilation: University of Manchester, United Kingdom
Pages: 737 - 740
Keywords: polyurethane, foam, nanocomposites, structure-development
This research involves in situ studies on the development of molecular and morphological structures during the processing of flexible, water-blown polyurethane foams containing layered silicate (montmorillonite) nanoparticles. Such materials possess enhanced mechanical properties combined with reductions in permeability and flammability, particularly important in materials applications that require the use of flexible polyurethane foams. The reactive processing of flexible water-blown polyurethane foam, from liquid monomers and oligomers, involves a complex combination of chemical and physical events. From room temperature and in less than five minutes, a liquid mixture of relatively low molar mass components is transformed into a segmented block copoly(urethane-urea) with a supramolecular architecture in the form of a cellular solid. The presence of layered silicate significantly affects structure development, which is monitored, using time-resolved techniques such as FTIR spectroscopy and chemo-rheometry, carried out under forced-adiabatic temperature conditions identical to those created during typical foam manufacture. The effects of silicate content and organic modification on phase-separation kinetics have been determined. Morphological structures of the finally-formed foams have been characterised using SAXS, optical and electron microscopy. These studies have led to a better understanding of the formation and properties of commercial polyurethane materials through a combination of experiments and modelling.