The mechanical and thermal properties of graphitic carbon nitride (g-C₃N₄)-based epoxy composites

Numerous ways to reinforce epoxy resin and improve its thermomechanical properties have been attempted using organic and inorganic nanoparticles. In this paper, graphitic carbon nitride (g-C₃N₄) nanoparticles were synthesized and used to improve the mechanical properties and thermal stability of epoxy composites. The g-C₃N₄ was synthesized from cheap melamine powder using a simple one-step thermal treatment, then was used to reinforce the resin at different weight percentages (wt%). X-ray diffraction, scanning electron microscopy (SEM), and Fourier infrared spectroscopy were used to characterize the g-C₃N₄ and ensure its successful synthesis by studying the changes in its crystal structure, morphology, and chemical structure. The filler was dispersed in the resin using a combination of ultrasonication and high shear mixing. The results showed that the mechanical properties were optimum when 0.5 wt% g-C₃N₄ was used. The tensile strength and fracture toughness of the resulting epoxy composite improved by 21.8% and 77.3%, respectively. SEM was used to investigate the morphologies of cracks formed in epoxy composite specimens after the tensile testing. The SEM micrographs of the fracture surface showed a transition from a brittle to a rough morphology, signifying the enhancement in the composites' toughness. Thermogravimetric analysis showed a good improvement in degradation temperature of up to 8.86% while dynamic mechanical analysis showed that the incorporation of g-C₃N₄ did not affect the material's glass transition temperature.