Polyurethane/poly(methyl methacrylate)/layered double hydroxide(PU/PMMA/LDH) nanocomposites were prepared by means of in situ polymerization with different amounts of the organo-modied LDH.The structure and morphology of nanoparticles were characterized through wide-angle X-ray diffraction(WXRD) and transmission electron microscopy(TEM).The effect of the content of LDH() on the thermal stability and relaxation behavior for PU/PMMA/LDH composites were investigated by using thermogravimetry analysis(TGA)

dynamic mechanical analysis(DMA) and broadband dielectric relaxation spectroscopy(BDRS).The results of TGA testing indicated that excellent thermal stability properties of PU/PMMA/LDH nanocomposites could be achieved when the LDH loading() was 0.5 wt%.An exfoliated dispersion of LDH layers in PU/PMMA matrix was varied through the WXRD and TEM observations when was less than 1.0 wt%.Based on the DMA results

it can be found that the maximum of loss factor(tanmax) of PU/PMMA/LDH nanocomposites increased and the glass temperature(Tg) decreased with the increase of .However

when was larger than 1.0 wt%

intercalated LDH layers reduced molecular mobility of polymer matrix and resulted in lower tanmax value and higher Tg than those of pure polymer.Moreover

it has been found by means of BDRS testing that all of relaxation processes for nanocomposites shift to higher temperatures and the relaxation parameter increases with the increase of the LDH loading due to the formation of hydrogen bonding between the surface of LDH and the hard segment of polyurethane.