Low Viscosity and High Strength Room Temperature Cured Epoxy Structural Adhesive Based on Different Amine Curing Agents

Epoxy resin has been widely used in the field of bonding owing to its low shrinkage and high adhesive performance, especially room temperature cured epoxy resin has been paid more and more attention in the field of construction engineering. However, it is still a great challenge to ensure that the epoxy adhesive with low viscosity has a high mechanical strength during rapid curing at room temperature in some construction engineering fields, such as filling repair, bonding steel reinforcement, etc. In this work, low viscosity and high strength room temperature cured epoxy structural adhesives were fabricated by using 1,4-butanediol diglycidyl ether (BDE) with difunctional groups as active diluent to reduce the viscosity of bisphenol F epoxy resin (BPF-170) and four kinds of amines, namely 2,4,6-Tris(dimethylamiomethyl)phenol (TAP), Triethylenetetramine (TETA), N-Aminoethylpiperazine (AEP) and Isophorondiamine (IPDA) as curing agents at room temperature, following by the investigation of the effects of the four different chemical structures of curing agents on the gelation time and mechanical properties of epoxy structural adhesive. Among the four kinds of epoxy structural adhesives, the BPF-170/BDE/IPDA system using alicyclic amine has the lowest viscosity of 77 mPa·s and the longest gelation time of 95.9 min. Furthermore, the BPF-170/BDE/AEP system using piperazine amine has the best mechanical properties with the shear strength, tensile strength, compressive strength and impact strength of 23 MPa, 62.5 MPa, 112.9 MPa and 2.82 kJ/m2, respectively. In addition, the four epoxy structural adhesives have great thermal stability. The initial decomposition temperatures are all above 280 ℃ and the maximum decomposition temperatures are all above 360 ℃. These four epoxy structural adhesives with low viscosity and high strength have significant application value in the fields of construction engineering, joint filling and potting repairing, etc.