Synthesis and characterization of polyurethane/montmorillonite nanocomposites by in situ polymerization

In this paper, a new type of organophilic montmorillonite, co-treated with cetyltrimethyl ammonium bromide (CTAB) and 4,4'-diphenymethylate diisocyanate (MDI), was modified and applied to prepare polyurethane/montmorillonite nanocomposites via in situ polymerization. The nanoscale montmorillonite layers were exfoliated and dispersed relatively homogeneously in the polyurethane matrix, and characterized by X-ray diffraction and transmission electron microscopy. The thermal degradation temperature of the nanocomposites increased, as compared with pristine polyurethane. Dynamic mechanical analysis confirmed the constraining effect of exfoliated montmorillonite layers on polyurethane chains, which benefited the increased storage modulus and increased glass transition temperature. Tensile tests showed that the exfoliated nanocomposites were reinforced and toughened by the addition of nanometer-size montmorillonite layers. (C) 2006 Society of Chemical Industry.