267 / 2022-08-27 23:42:51

Comparative study of different molecular structures of diluents on the curing of epoxy adhesives and the bonding properties with concrete

Repair materials; Concrete crack repair; Epoxy resin; Adhesives; Molecular structure

Epoxy adhesives own various advantages of high strength, fast curing speed and good chemical corrosion resistance, hence become one of the most extensively organic repair materials. Aim to satisfy the different needs of various engineering, it is necessary to develop various epoxy resin materials with different properties by tailoring their molecular structure. In this paper, a precursor (PPM) reacted by 1,4-butanediol and trimethylolpropane triglycidyl ether was firstly synthesized. Then, PPM and three commercial reactive diluents, namely alkyl C12-C14 glycidyl ether, butyl glycidyl ether, 1,4-butanediol diglycidyl ether were separately used to prepare epoxy adhesives, the effects of various types and contents of reactive diluents on the viscosity, exothermic temperature, mechanical properties and bonding strength with concrete of epoxy adhesives were comparatively studied. The results indicated that all reactive diluents can drastically reduce the viscosity of epoxy adhesives while increasing the ductility of cured products. The molecular structure of the diluents within epoxy adhesives has a significant impact on the exothermic peak temperature and bonding strength with concrete. The samples with monofunctional or lower epoxy value diluents exhibit lower bonding strength at the epoxy-concrete interface. In addition, high epoxy value of reactive diluents causes the increase of the peak exothermic temperature. More interestingly, the synthetic PPM with the introduction of a certain amount of polar hydroxyl groups and partial consumption of epoxy groups, which makes the PPM-based epoxy adhesives simultaneously show excellent interfacial bonding properties and reducing the peak exothermic temperature. This study implies that the molecular structure design of epoxy adhesives has great potential to meet the various requirements in improving the serviceability of transportation infrastructure.