Graphite oxide (GO) and amine surfactant intercalated graphite oxide (GOS) filled maleated polypropylene (PPgMA) nanocomposites were prepared directly by solution blending. In this study, the effects of the surfactant intercalation on the crystalline structure, thermo-mechanical, and dielectric properties of PPgMA/GO and GOS composites are reported. Wide-angle X-ray diffraction exhibited a lower intensity diffraction peak of the monoclinic (a) phase of PPgMA for PPgMA/GOS composites compared with the unfilled sample. Differential scanning calorimetry exhibited a single characteristic melting peak of monoclinic (a) crystalline phase. The incorporation of GOS hardly showed any change in Tm. However, the significant decrease in the melting enthalpy of PPgMA/GOS composite, which was lower than that of GO filled PPgMA, demonstrated the high degree of dispersion of the GOS flakes in the PPgMA matrix. Dynamical mechanical analysis indicated that incorporation of GO or GOS into PPgMA increased both the storage modulus and the glass transition temperature, due to the hydrogen bonding between GO and the maleic anhydride group of PPgMA. Dielectric analyzer showed significant increase in both dielectric permittivity and dielectric loss at high temperature regimes in the GOS nanocomposites. The finely dispersed GOS in the PPgMA matrix manifested the interfacial polarization, which gave rise to much greater e' and e? than that of PPgMA/GO hybrid. (c) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012