PSI - Issue 52

Mayu Morita et al. / Procedia Structural Integrity 52 (2024) 195–202

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Author name / Structural Integrity Procedia 00 (2019) 000 – 000

Fig. 3 Stress-strain curves of epoxy/lignin polymers in bulk state obtained from MD tensile simulation

Fig. 4 Radial distribution function for each interface model. Table 2 shows the interfacial energy for the interface models. All interface energies have negative value, meaning that forming an interface is more stable than isolating the polymer and the reinforcement. This table also shows following material orders associated with interfacial stability. For matrix polymer, EGL forms a more stable interface than EL. For reinforcement, the stability increases in the order of pure graphene, graphene functionalized with oxygen, and graphene functionalized with hydroxyl group. To understand these orders of the interface stability, Figure 4 represents the radial distribution functions between carbon atoms of functionalized graphene and the constituent atoms of matrix polymer. The horizontal axis in this figure is the distance from the carbon atoms of functionalized graphene, and different colored lines represent the oxygen (blue), hydrogen (orange), and carbon (gray) atoms of the matrix polymers, respectively. For graphene modified with hydroxyl groups, sharp peaks of oxygen atoms in the polymer are