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Enhanced thermal properties of poly(ethylene tetrasulfide) via expanded graphite incorporation by in situ polymerization method

In this study, a novel poly(ethylene tetrasulfide) (PETS)/expanded graphite (EG) nanocomposite with 40°C improvement in melting point is prepared via in situ polymerization technique. The morphology, chemical characteristics and the structural behavior of nanocomposites are characterized using scanning electron microscopy, Fourier transform infrared spectroscopy and x-ray diffraction (XRD) techniques, respectively. XRD observations show about 0.1 nm increase in d-spacing of PETS crystals in the presence of 2 wt% EG in nanocomposite. This behavior could be related to the intercalation of polysulfide macromolecules in the interlayer structure of EG sheets. Furthermore, the thermal properties of nanocomposites are investigated using differential scanning calorimetry and thermogravimetric analysis techniques. The thermal degradation temperature of nanocomposite containing 2 wt% graphite shows an improvement of about 10°C compared to unfilled polysulfide. Moreover, the chemical resistance of nanocomposites in different common solvents increases in the presence of EG, which could be accounted as a clear proof of interconnections for EG and macromolecular structure of the polymer.