Abstract
Due to its superior mechanical properties, graphene (Gr) has the potential to achieve high performance polymer-based nanocomposites. Previous studies have proved that defects in the Gr sheets could greatly reduce the mechanical properties of Gr, while the Stone-Wales (SW) defect was found to enhance the interfacial mechanical strength between Gr and epoxy. However, the combined effects of defects on the overall mechanical properties of Gr/epoxy nanocomposites have not been well understood. In this paper, the effect of the SW defect on the mechanical properties of Gr/epoxy nanocomposites was systematically investigated by using molecular dynamic simulations. The simulation results showed that the SW defect would degrade the mechanical properties of nanocomposites, including the Young’s modulus and in-plane shear modulus. Surprisingly, the transverse shear modulus could be remarkably enhanced with the existence of SW. The reinforcing mechanisms were mainly due to two aspects: (1) the SW defect could increase the surface roughness of the Gr, preventing the slippage between Gr and epoxy during the transverse shea; and (2) the nanocomposite with defective Gr enables a higher interaction energy than that with perfect graphene. Additionally, the effects of temperature, the dispersion and volume fraction of Gr were also investigated.
Highlights
Epoxies with cross-linked network structure exhibit excellent mechanical properties, good chemical stability and durability, which makes them widely used in electronic packaging and the automotive and aerospace fields [1,2,3,4]
Due to the temperature-dependent behavior of mechanical properties of Gr, the mechanical properties of composite decreased with the increase of temperature, and the sensitivity to temperature increased with the volume fraction
Since the mechanical properties of Gr were significantly decreased by the defect, the longitudinal Young’s modulus and in-plane shear modulus would be significantly degraded with the existence of SW defect
Summary
Epoxies with cross-linked network structure exhibit excellent mechanical properties, good chemical stability and durability, which makes them widely used in electronic packaging and the automotive and aerospace fields [1,2,3,4]. The incorporation of nanofillers was the most common and effective way to improve the mechanical properties of epoxy-based composites [7,8]. Among various fillers, owing to its extraordinary mechanical properties Numerous experimental works have proven that the mechanical properties of epoxy could be improved with the incorporation of Gr, including Young’s modulus [15], tensile strength, fracture toughness [16] and glass transition temperature [17]. Rafiee et al [15] found that Gr could
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