Dispersibility of clay and crystallization kinetics for in situ polymerized PET/pristine and modified montmorillonite nanocomposites

Nanocomposite materials composed of poly (ethylene terephthalate) (PET) and montmorillonite (MMT) clays were prepared by in situ polymerization. Samples consisted of PET blended with various quantities of either pristine (Na+-MMT) or organically modified MMT (A10-MMT). The morphology and thermal and mechanical properties were evaluated for each sample. TEM micrographs, acquired at a 20 nm resolution, provide direct evidence of exfoliation of the clay particles into the PET matrix and show the effect of the alkyl-modifier on clay dispersibility. The dispersion of PET/A10-MMT was greater than that observed for the PET/Na+-MMT nanocomposites. The greatest degree of exfoliation occurred for PET/A10-MMT 0.5 wt %. However, PET/Na+-MMT exhibited higher crystallization temperatures and rates suggesting that Na+-MMT is a more efficient nucleating agent. Both mechanically and thermally, PET/A10-MMT nanocomposites exhibited superior properties over pure PET. (c) 2008 Wiley Periodicals, Inc.