Influence of a terpolymer compatibilizer on the nanostructure of poly(trimethylene terephthalate)/montmorillonite nanocomposites

The use of a compatibilizer to improve the interactions between poly(trimethylene terephthalate) (PTT) and an organically treated montmorillonite (MMT) clay was studied. Nanocomposites, with and without compatibilizer, were obtained using a torque rheometer; their nanostructures were analyzed by wide angle X-ray diffraction (WAXD), transmission electron microscopy (TEM), steady state and dynamic rheological measurements, and Fourier transform infrared analysis (FT-IR). Only intercalated structures were obtained when no compatibilizer was added, independent of the mixing method (one or two steps); when the compatibilizer was added, however, intercalated and exfoliated structures were obtained, depending on the masterbatch composition. When the PTT was not present in the masterbatch, two-phase exfoliated structures were obtained, with a disperse phase composed of nanoclay's lamellas and reticulated compatibilizer and a matrix phase composed of PTT. The compatibilizer cured due to the presence of the nanoclay's surfactant; a mechanism of cure was proposed in which the epoxide rings of the compatibilizer reacted with the hydroxyl groups of the nanoclay's surfactant, forming ether cross-linkages. It was also concluded that in order to obtain one-phase exfoliated structures the two steps mixing method using a masterbatch composition of 50 wt% of PTT, 25 wt% of compatibilizer, and 25 wt% of nanoclay gave the best results; after further dilution in the PTT, an exfoliated nanocomposite with a final concentration of 5 wt% of compatibilizer and 5 wt% of nanoclay was obtained. Copyright (C) 2008 John Wiley & Sons, Ltd.