Thermal and Thermo-mechanical Properties of Poly(ethylene terephthalate) Nanocomposites

In this study poly(ethylene terephthalate) (PET)/clay nanocomposites with two different weight percentages of montmorillonite (MMT) have been prepared by melt-extrusion technique. The X-ray diffraction (XRD) patterns and transmission electron microscopic (TEM) images reveal the formation of intercalated nanocomposites. The melting and crystallization behaviors of neat polymer and nanocomposite samples have been investigated by using both conventional and temperature modulated differential scanning calorimetry (TMDSC). The DSC results for compression molded samples after cooling show successive melting with an endothermic peak accompanied by a shoulder for nanocomposite samples. This is due to the presence of two different sizes of crystallites. DSC and TMDSC results for quenched samples show melting is followed by cold crystallization and in this state initial percent of crystallinity present in nanocomposite samples are higher than that of neat PET sample. For all samples, TMDSC results also confirm the melting is associated with re-crystallization phenomenon. The dynamic mechanical analyses (DMA) show in all temperature range, noticeably in the higher temperature region the nanocomposites exhibit tremendous improvement of modulus; but the slight difference in clay content doesn’t effect significantly. The thermogravimetric analyses (TGA) reveal the overall thermal stability of PET matrix slightly improves after nanocomposite preparation.