TiCl4/MgCl2/clay compound catalyst was prepared by chemical reaction. Exfoliated polypropylene （PP）/clay nanocomposites were synthesized by in situ polymerization with this compound catalyst. Effects of polymerization temperature, polymerization time, propylene pressure, solvent consumption and pre-treat time of catalyst on catalyst activity and catalytic stereospecificity were studied. Under optimal conditions, activity of the nano-compound catalyst is about 88.3 kg/（mol Ti-h）. Isotacticity of PP obtained in the nanocomposites is in the range of 89%-99%, and its melting temperature is about 159℃. The weight-average molecular weight of PP can reach 6.7 × 10^5 - 7.8 × 10^5, and the molecular weight distribution is between 7.7 and 7.9.
Diphenyl （4-hydroxyphenyl） hexadecyl phosphonium bromide （POH） -modified montmorillonite （POHMMT） was used to prepare a novel TiC14/MgC12/POHMMT compound catalyst and exfoliated iPP/POHMMT nanocomposites were prepared by the in situ intercalative polymerization of propylene with the TiC14/MgC12/POHMMT compound catalyst. The POH surfactants don＇t change the catalytic characteristic of the Z-N catalyst and the obtained PP presents high isotacticity, normal molecular weight and molecular weight distribution. The WAXD, SAXS and TEM results demonstrate the highly exfoliated iPP/POHMMT nanocomposites were produced by the in situ polymerization with this novel catalyst, while the intercalated iPP/Na＋MMT nanocomposites were produced with the TiC14/MgC12/Na＋MMT compound catalyst. Through this approach, in situ propylene polymerization can actually take place between the silicate layers and lead not only to PP with high isotacticity and molecular weight, but also to highly exfoliated PP nanocomposites.
