Study on epoxy repair agents under the influence of bisphenol A diglycidyl ether (DGEBA): from macro to nano scale

Abstract

To improve the use value and economic applicability of building components, the mechanism of performance improvement of epoxy crack repair agent was explored. The influence mechanism of diglycidyl ether (DGEBA) on the epoxy system was revealed through macroscopic experiments and microscopic molecular dynamics (MD) simulation. The glass transition temperature (Tg) of the epoxy system was obtained by differential scanning calorimetry (DSC). The mechanical properties of the epoxy system were characterized by tensile, bending, and compression tests. On this basis, the shrinkage and flexural properties of mortar bonded specimens were tested to characterize their engineering adaptability. The static mechanical properties, concentration distribution, mean square displacement (MSD), fractional free volume (FFV), radial distribution function (RDF), the distribution of H bonds, and cohesive energy density (CED) of the simulated system were analyzed by MD simulation. It was found that the content of DGEBA affected the comprehensive properties of epoxy. When DGEBA: m-PDA = 5:1, the mechanical and thermodynamic properties of epoxy are significantly improved. DGEBA can significantly improve the stability of interatomic bonding of epoxy systems, reduce the movement ability of molecular chains, make the distribution of molecular chains more concentrated, improve the packing density of the system, thus greatly improving the elasticity and stiffness of the system, and enhance the mechanical properties. This method provides a new way to repair cracks in building components.