Preparation and properties of single-walled carbon nanotubes/poly(butylene terephthalate) nanocomposites

A neat poly(butylene terephthalate) (PBT) polymer and functionalized single-walled carbon nanotubes (F-SWNTs)/PBT nanocomposite films were prepared by solution casting technique. The SWNTs were functionalized by acid treatment, which introduced carboxylic groups onto the SWNTs. The morphological studies showed that the F-SWNTs were embedded and dispersed well within the PBT polymer matrix. The POM study illustrated that a neat PBT showed Maltese-type spherulites. It was also observed that the size of neat PBT spherulites was larger than F-SWNTs/PBT nanocomposite spherulites, which might be due to the nucleation effect of F-SWNTs in the case of nanocomposites. The thermal stabilities and mechanical properties such as stress yield and moduli of F-SWNTs/PBT nanocomposites were enhanced as compared to neat PBT. The DSC study showed that the melting temperature (T _m) of PBT was slightly increased by addition of F-SWNTs. This increase in T _m might be due to the formation of compact structure, which was formed through different types of molecular interactions with addition of F-SWNTs. It was also found that initially the solvent (distilled water, kerosene, 2 M HNO₃ solution) uptake by neat PBT polymer and its nanocomposites increased gradually, which became steady after specific intervals for each sample. The results also exhibited that the solvent uptake of F-SWNTs/PBT nanocomposites was less than neat PBT.