Degradation of epoxy/glass interface in hygrothermal environment: An atomistic investigation

The degradation at the glass fiber/matrix interface through molecular dynamics simulations in hygrothermal environment is investigated. The glass fiber reinforced polymer composite has been modeled using a cross-linked epoxy matrix and amorphous silica substrate. The degradation mechanism in hygrothermal environment is indicated through the reduction of decreased adhesion energy and the weakened intermolecular interactions with the consideration of hydration bond. Furthermore, softened epoxy molecules in hygrothermal conditioning possess a lower density near the fiber surface, which inhabits the stress transfer between fiber and matrix, eventually leading to the deteriorated interfacial adhesion. Our simulation results echo with the experimental measurements, which can be further calibrated and utilized as inputs in micromechanical models to bridge the gap between the macroscopic and microscopic behavior of civil infrastructures. [Display omitted] •An atomistic simulation framework to study the hygrothermal deterioration of polymer-matrix composites is proposed.•Local interfacial deterioration causes the deteriorated fiber/matrix bond in hygrothermal environment.•Hygrothermal environment reduces the adhesion energy at fiber/matrix interface.•The hydrophilicity of hydroxylated silica surface aggravates the interfacial degradation.•The water-swellable polymer inhibits the stress transfer and promotes the interfacial mismatches.