The OrganoClay was prepared by alkyl phosphonium ions treating of Namontmorillonite. The X-ray diffraction(XRD) patterns of Na-Clay and OrganoClay shows that the position of the (001) plane diffraction peak of the NaClay appears around 5.94°

corresponding to the interlayer distance (d) of 1.48 nm calculated from the Bragg law

and the position of the (001) plane diffraction peak of the Org-Clay appears around 4.99oC

d=1.78 nm. The result proves that the alkyl phosphonium are intercalated into the galleries of the clay layers. The polypropylene (PP)/Org-Clay nanocomposites were prepared by melt intercalation and XRD and transmission electron microscopy (TEM) both indicated that PP chains could be intercalated into the interlayer of the Org-Clay. The nanocomposites possess exfoliation structure and intercalation structure. The process of melting for PP/Org-Clay nanocomposites were studied with differential scanning calorimetry (DSC)

and the result indicted that the addition of the Org-Clay had hardly effect on the degree of crystallization for PP. XRD results shows the position of the γ-PP(130) plane diffraction peak of the PP/Org-Clay nanocomposites appears around 19;8°and DSC heating cuvers of PP/Org-Clay nanocomposites at speed of 5 K/min revealed that the γPP melt peak of the PP/OrgClay nanocomposites appearing around 149℃. It can inferred that the Org-Clay may promote the formation of γ-phase PP crystallites in the PP/Org-clay. When adding 5 wt% Org-Clay，the mass fraction of γ-phase PP is about 12%.