Epoxy/graphene oxide/liquid polysulfide ternary nano-composites: rheological, thermal and mechanical, characterization

Abstract

Despite its functionality, one major drawback associated with cured epoxy resin is its brittle nature. In order to overcome this problem, liquid polysulfide (PSf) and graphene oxide (GO) were incorporated into an epoxy resin. The current study investigates the effect of the weight fraction of PSf (20%, 33%, and 50%) on the glass transition temperature (T_g), thermal stability, rheological, and mechanical properties of epoxy/GO/PSf ternary nano-composites. The weight fraction of GO was kept constant and set at 0.1% to confirm the percolation threshold. The rheological measurements demonstrated that as the amount of PSf is increased in an uncured sample, the strength of the network is increased, too. Differential scanning calorimetry revealed that phase separation occurred during curing of the epoxy resin in a way that three different regions were detected. The X-ray diffraction peak proved that the d-spacing between GO sheets was increased to 16.68 Å at 50% PSf loading. The tensile strength of the nano-composites followed a descending trend vs. PSf content. However, the sample containing 50% PSf scored the highest fracture value. This was correlated to a plasticizing effect of PSf on the cured epoxy. Finally, thermogravimetric analysis showed that degradation occurred faster and at lower temperature as the amount of PSf increased.