Atomistic study of interfacial creep behavior in epoxy-silica bilayer system

•The interfacial creep behavior in the bilayer material system is investigated at nanoscale.•The threshold stress is found for the onset of interfacial creep.•The relationship between loading and creep displacement is quantified by an analytical model.•The microstructural evolution is captured to reveal the mechanism during interfacial creep process.

Epoxy-bonded bilayer material systems are commonly used in various engineering applications. The mechanical durability of these material systems are generally related to the interfacial properties between the bonded materials, which have aroused great concern for ensuring the long-term performance. In this paper, the interfacial creep behavior in bilayer system consisting of SU-8 monomer and silica substrate is investigated using molecular dynamics simulations. The threshold stress is found for the onset of interfacial creep in bilayer material system. The relationship between creep displacement and applied constant force is quantified by an analytical model. The microstructural changes during creep process are captured to demonstrate creep deformation process, including extension and sliding movement of epoxy, which unravels the mechanism of creep behavior at atomistic level. This study provides a new approach to understand the creep deformation at the nanoscale, and the corresponding molecular dynamics simulations show the promising results to obtain the information of the interfacial creep behavior in the bilayer material system.

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