STUDY ON TENSILE FRACTURE BEHAVIOR AND MECHANICAL PROPERTIES OF GO BASED ON MOLECULAR DYNAMICS METHOD

In comparison with graphene, the graphene oxide (GO) has better hydrophilicity, dispersion performance and reaction activity, which makes it easier to interact with other materials to form composites with excellent properties. But on the other hand, due to the complexity of the electronic structure of the GO, there are some differences in the research of mechanics of GO at present. For this purpose, in the present paper, a random distribution model of GO containing the hydroxyl groups,epoxy groups and carboxyl groups was established based on the molecular dynamics method. And then, the tensile fracture behavior was analyzed by uniaxial tensile numerical simulation. The results illustrated that the epoxy groups which are far away from hydroxyl and carboxyl groups had induce effect on the fracture of GO. In addition, the mechanisms were explained from three aspects,which are the chemical bonding, system energy and stress distribution. Additionally, the influence of the coverage of oxygen-containing functional groups of hydroxyl groups, epoxy groups and carboxyl groups on the stress-strain curve, ultimate strength and ultimate strain of GO were further studied. The results showed that the ultimate strength and ultimate strain of GO decreased with the increase of the coverage of oxygen-containing functional groups of hydroxyl groups,epoxy groups and carboxyl groups. According to the analysis, the main reason is that the oxygen-containing functional groups of hydroxyl groups, epoxy groups and carboxyl groups destroy the sp^2hybrid form in the original graphene surface, thus weakening the bonding energy between atoms. Thereby, The greater the coverage of the oxygen-containing functional groups of hydroxyl groups, epoxy groups and carboxyl groups, the greater the amount and degree of weakened bonding energy, and the lower the ultimate strength of GO. The research results have certain reference value and significance for engineering application and basic research of GO.