Synthesis and characterization of polyurethane/montmorillonite nanocomposites

A kind of polyurethane/organically modified montmorillonite (PU/OMMT) nanocomposite based on poly(propylene glycol) I 4-butanediol and 4,4-diphenylmethane diisocyanate was prepared by solution intercalation technology. The results of wide angle X-ray diffraction and TEM showed that the gallery distance of OMMT in the PU matrix was 3 similar to 4 nm. As the hard segment content increased, the molecular chains of PU had difficulty in diffusing into the silicate layer galleries for intercalation. Transmission electron microscopy photographs showed that OMMT layers were dispersed well into the PU matrix on the nanometer scale, and an ordered intercalation structure was obtained. Compared with those of pure PU, the tensile strength, the tear strength and the elongation at break increased by about 43% 28% and 18% for PU/OMMT(92/8), respectively. The water absorption decreased with increasing the amount of OMMT. Thermogravimetric analysis showed that the PU/OMMT nanocomposites displayed a little higher thermal resistance than that of pure PU in the second pyrolysis stage.