Curing kinetics and mechanical properties of an underwater SiO2/epoxy adhesive

ABSTRACT In this study, an SiO2/epoxy adhesive that can be cured in a wet/water environment was prepared. Nonisothermal differential scanning calorimetry was used to evaluate the curing reaction of this adhesive. Kinetic parameters of the adhesive were obtained using the Kissinger, Ozawa, Flynn–Wall–Ozawa, and Kissinger–Akahira–Sunose methods. The results show that the isoconversional methods can well explain the curing behavior of SiO2/epoxy adhesive. Further, the tensile lap-shear strength of the prepared adhesive cured in air and water increased by 35.96% and 32.07% than pure epoxy adhesive, respectively. Although the presence of water molecules affects the bond strength of the SiO2/epoxy adhesive, its bond strength underwater was only 1.45 MPa lower than that in air. Compared to the pure epoxy resin, the tensile and flexural strength of SiO2/epoxy adhesive cured in air were 12.23%, 6.67% higher and those of the adhesive cured in water were 10.24% and 6.62% higher, respectively. Compared to the pure epoxy resin, the tensile and flexural modulus of SiO2/epoxy adhesive cured in air increased by 13.71%, 10.25% and those of the adhesive cured in water increased by 11.21% and 10.41%, respectively.