[SY-H11] Symposium H-11

[SY-H11] Molecular dynamics simulation of the detachment force between graphene and epoxy resin

^○Kazuki Mori¹, Makoto Yabe², Yuji Kohno², Jun Koyanagi³ (1.ITOCHU Techno-Solutions Corporation, Japan, 2.Yokohama National University, Japan, 3.Tokyo University of Science, Japan)

We introduced a computational method to investigate the shear detachment strength at a carbon fiber/epoxy resin interface using molecular dynamics simulations. In the computational model, the graphene molecular structure was assumed to be that of a simple carbon fiber. The interaction energies calculated for the epoxy bulk phase were in good agreement with the experimental data in our previous work [1], however, the estimates of surface energy between carbon fiber and epoxy resin were missing. In this work, we calculated the surface energy and estimated the correlation between surface energy and shear detachment strength of the carbon fiber/epoxy resin interface. All calculations were performed using Exabyte.io platform [2]. The calculated surface energy was confirmed to be related to the experimental shear strength: the surface energy increased with increase in the resin density near graphene. In addition, molecular structures of bulk resin and the resin near graphene surface regions were found to be different. Our results suggest that the carbon fiber and epoxy resin have strong interaction at the interface. In the vicinity of graphene, the resin molecular structure deformed into a flattened state. We propose this to happen due to the influence of CH/π orbitals. The CH/π interaction is a weak interaction (0.1 kcal/mol), however, the compound effect of the numerous weak interaction forces leads to the rise of a strong interaction at the surface between graphene and resin. Because of this, the carbon composite becomes a high-strength material. We further simulated the stress-strain curve of the graphene/epoxy composite model because the above interaction might be related to tensile stress. We found that the crack formation started from the epoxy interface layer and progressed to the bulk epoxy layer.
[1] K. Mori, N. Matsumoto, S. Nomoto, K. Tsuruta, OJCM (2017) 7, 179-184
[2] https://exabyte.io/