Effect of Aliphatic and Aromatic Chain Extenders on Thermal Stability of Graphene Oxide/Polyurethane Hybrid Composites Prepared by Sol‐Gel Method
Reza Behnam, Hossein Roghani‐Mamaqani, Mehdi Salami‐Kalajahi, Hanieh Mardani
Abstract
Abstract Hybrid composites of graphene and polyurethane (PU) were prepared via sol‐gel method. The isocyanate‐terminated PUs with chain extenders of pyromellitic dianhydride (PMDA) and butanediol were reacted with (3‐aminopropyl) triethoxysilane (APTES) to obtain Polyurethane with PMDA chain extender (PUI) and Polyurethane with BD chain extender (PUBD), respectively. Sol‐gel reaction between the silane‐modified polyurethanes with APTES‐modified graphene oxide resulted in the hybrid composites with high thermal degradation temperature and char content. Results of Fourier‐transform infrared spectroscopy and proton nuclear magnetic resonance analysis confirmed chemical modification of graphene and successful preparation of the bifunctional silane‐modified PUI and PUBD, respectively. Based on the thermogravimetric analysis (TGA) results, PMDA chain extender resulted in higher degradation temperature and char content in the hybrid composites. In addition, siloxane networks formed by sol‐gel process resulted in synergistic effects on improving thermal stability of the PU materials. X‐ray diffraction results in addition to the scanning and transmission electron microscopy images confirmed successful oxidation of graphite and also its modification process.