Effects of moisture ingress on the bond between carbon fiber and epoxy resin investigated with molecular dynamics simulation

YR Xiao and GJ Xian, POLYMER COMPOSITES, 39, E2074-E2083 (2018).

DOI: 10.1002/pc.24459

This work aims to explore the mechanism of moisture ingress on the degradation of the fiber reinforced polymer composites. A quantitative analysis of the surface free energy variation of the carbon fiber/epoxy resin interface with and without water ingress was performed using molecular dynamics (MD) methods. The results show that a reduction by 58% of the surface free energy was found with saturated water uptake, which was comparable with the reduction of the interfacial shear strength tested by the microbond experiment. Furthermore, the MD results revealed that water was condensed in the interfacial area and interact with the epoxy resin, weakening the interfacial adhesion between carbon fiber and epoxy resin. Hydrogen bonds are found between epoxy and water molecules. As revealed, the Coulomb forces between water and epoxy molecules play a critical role in the interfacial debonding process. POLYM. COMPOS., 39:E2074-E2083, 2018. (c) 2017 Society of Plastics Engineers

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