Ma et al. [113] prepared PP/OMMT nanocomposites with improved dynamic
mechanical properties and thermal properties using an OMMT/MgCl 2 /TiCl 4 catalyst.
At temperatures higher than T g , with 8.1 wt% clay content, the PP nanocomposites
exhibited a storage modulus three times higher than that of the pure PP. In a similar
report, Yang et al. [114] prepared PE/MMT nanocomposites using a MMT/MgCl 2 /
TiCl 4 catalyst activated by Al(Et) 3 . The catalyst was prepared by first diffusing
MgCl 2 into the swollen MMT layers, followed by loading of TiCl 4 on the inner/
outer layer surfaces of MMT/MgCl 2 . The intercalation of MMT layers by MgCl 2 and
TiCl 4 was demonstrated by the enlarged interlayer spacing, as determined by
WAXD. They reported a significant improvement in the tensile strength of the
resultant PE nanocomposite compared to that of virgin polyethylene of comparable
molecular weight. Figure 17 shows a schematic representation of the reaction
between the clay surface and the MgCl 2 and TiCl 4 loading.
Fig. 16 DSC thermograms of pure PE (a), PE/clay 1.61 wt% (b), PE/clay 2.43 wt% (c), and
PE/clay 3.76 wt% (d). Reproduced with kind permission from Cui et al. [84]
Fig. 17 Intercalation of TiCl 4 on MMT/MgCl 2 support. Reproduced with kind permission from
Ma et al. [113]
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