Rheological studying the effect of reduced graphene oxide nanoparticles on the creep behavior of epoxy coating of pipelines: Part I—Constitutive equations

In this article, the creep behavior of pure and reinforced epoxy‐polyamine samples with different amounts of reduced graphene oxide (RGO) at two temperature levels of 28 and 40°C is investigated experimentally and analytically to develop the creep‐associated constitutive equations. Mechanical properties and creep behavior of samples are obtained by carrying out tensile and creep tests at different stress levels. The Burgers model and modified Burgers model are used to investigate the creep behavior of pure and reinforced epoxy. The experimental results show that the addition of 0.5% RGO increases the yield strength of the samples by 51% and the maximum strain by 20%. Also, by considering the production costs of reinforced epoxy, the sample reinforced with 0.5 wt% graphene is selected as the optimum added value of RGO nanoparticles which results in the desired failure load and creep resistance. Additionally, it is discovered that the modified Burgers model, albeit having a larger computing cost, can accurately simulate samples' creep behavior. Furthermore, Fourier transform infrared spectroscopy and scanning electron microscopy analyses are performed on the samples and it is found that the addition of RGO particles improves the microstructure of the reinforced samples. The creep behaviors of pure and reduced graphene‐oxide (RGO) reinforced epoxy‐polyamine samples are investigated. Creep behavior of samples is obtained by carrying out experimental tests. Based on the results, 0.5 wt% RGO is selected as the optimum added value. This improves the microstructure of the reinforced samples. It is shown that modified Burgers model can accurately simulate samples' creep behavior.