Deterioration of carbon fiber/matrix interface in humid environments and influence of silicon coupling agent modification: An atomistic investigation

Extended exposure to moisture could harm the carbon fiber/matrix interface, threatening CFRP's reliability service. This paper introduces a method that develops molecular dynamics models to analyze the deterioration of the interface and the influence of the silicon coupling agent. The mechanical properties of the interface in humid environments are obtained through simulations. The interfacial shear strength decreases by 25.68% and 26.96% respectively, demonstrating good consistency between experiment and simulation. The free volume and water distribution function characterize the extent of interface deterioration under varying moisture levels. The water molecules weak interface interactions through hydrogen bonding, leading to abnormal swelling of nanoscale structure. This inhibits the stress transfer between the fiber and matrix, weakening the interfacial shear strength. Additionally, the silane coupling agent reduces the pathway for water transmission, diminishing water diffusion. It can enhance the water damage resistance capability of interfacial strength.