Thermal performance of poly(ethylene disulfide)/expanded graphite nanocomposites Amir Hossein Haghighi • Milad Sheydaei • Ahmad Allahbakhsh • Marzieh Ghatarband • Fatemeh Sadat Hosseini Received: 9 November 2013 / Accepted: 10 March 2014 Ó Akade ´miai Kiado ´, Budapest, Hungary 2014 Abstract In this study, the influences of expanded graphite oxide (EG) nanosheets presence with and without surfactant on structural and thermal performance of poly(ethylene disulfide) (PEDS)-based nanocomposites are investigated. Sodium dodecylbenzenesulfonate (SDBS) is used as a surfactant for the preparation of modified-EG nanosheets. The structural, morphological, and thermal properties of prepared nanocomposites are studied using X-ray diffraction (XRD), scanning electron microscopy, and differential scanning calorimetry techniques, respec- tively. XRD patterns of nanocomposites reveal that a high degree of expanded graphite nanosheets dispersion is achieved with and without surface modification using in situ polymerization method. Moreover, the presence of immobilized polysulfide chains near the interface region of nanosheets is suggested as a possible reason for the observed increase in the number of semi-crystalline organic fractions in the structure of PEDS via EG nano- sheets incorporation. In addition, the morphology of SDBS-modified-EG loaded nanocomposite shows a smoother fracture surface than unmodified-nanosheets reinforced nanocomposite. Therefore, more interactions between nanosheets and polysulfide chains are expected in the structure of unmodified-EG reinforced nanocomposite. Moreover, thermal resistance and degradation kinetics of prepared nanocomposites are studied using thermogravi- metric analysis results and degradation activation energy calculations, respectively. The required activation energy for the degradation process of SDBS-EG loaded nano- composite is about 140 kJ mol -1 lower than the required degradation activation energy of unmodified-nanosheets reinforced nanocomposite. Keywords Expanded graphite  Degradation kinetics  Nanocomposites  Polysulfide  Thermal properties Introduction The degradation process of polymers is an important index, which directly relates to polymer properties. Generally, the polymer degradation process is the deterioration of poly- mer properties due to different factors such as severe light, thermal, or mechanical loads [1]. Therefore, as properties are directly affected by structural performance, degradation behavior of polymers and their composites strongly depends on their structures. Polysulfide elastomers are a class of polymers with superior thermal and environmental stability as well as high solvent resistance and good adhesion properties [2, 3]. These properties made poly- sulfide polymers perfect candidates for many novel appli- cations such as bipolar plates of fuel cells, electrolyte in solar cells, gene delivery purposes, electrolyte in rechargeable batteries, and carbon-based reinforced nano- composites [4–7]. Carbon-based nanosheets including carbon nanotubes, single- and multi-layered graphene as well as expanded graphite have recently attracted many attentions as an A. H. Haghighi  A. Allahbakhsh (&)  M. Ghatarband Department of Polymer Engineering, Shiraz Branch, Islamic Azad University, Shiraz, Iran e-mail: ahmad.allahbakhsh@gmail.com; a.allahbakhsh@modares.ac.ir M. Sheydaei Department of Polymer Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran F. S. Hosseini Young Researchers Club, Shiraz Branch, Islamic Azad University, Shiraz, Iran 123 J Therm Anal Calorim DOI 10.1007/s10973-014-3752-0