A kind of organically modified montmorillonite (OMMT) treated by cetryhrimethyl ammonium bromide (CTAB) was grafted with 4

4'-diphenylmethane diisocyanate (MDI) by it’s hydroxyl group(--OH) acted with isocyanate group (一NCO)．This MDI modified montmorillonite was abbreviated as MOMMT．Thenceforth

the MOMMT was applied to prepare polyurethane(PU)/MOMMT nanocomposites based on poly(propylene glycol)

1

4-butanediol and MDI via solution intercalation technology Compared with OMMT

the interlayer spacing of MOMMT was enlarged from 2.07 nm to 2.39 nm．PU chains intervened the galleries between MOMMT layers during solution intercalation．and an intercalated PU/MOMMT nanocomposite was obtained．The tensile strength and tear strength of PU/MOMMT nanoeomposites were higher than those of PU/OMMT nanocomposites．Thermal stability of PU/MOMMT nanocomposites was lower than that of the PU/MMT composite because of the degradation of CTAB and MDI in the first step of thermodegradation

whereas in the second step they exhibited higher thermal stability due to the hish barrier effect of the silicate layers dispersed on the nanometer scale and strong interface interaction between the silicate layers and the PU chains.