Effects of Elevated Temperature Curing on Glass Transition Temperature of Steel/CFRP Joint and Pure Epoxy Adhesive

Glass transition temperature (Tg) of the steel/epoxy/CFRP composite bond can affect the service and fire performance of the system. Two test series were conducted to evaluate the Tg of the pure epoxy adhesive and the steel/epoxy/CFRP bond. A total of twenty-six double strap joints and pure epoxy adhesive samples were prepared under different curing conditions to check the Tg of bond. Six different curing conditions were used. The test results revealed that the elevated temperature curing has a significant affect on the Tg of steel/epoxy/CFRP bond and pure epoxy adhesive. A considerable improvement of Tg was noted in the joint with elevated temperature curing when compare with the epoxy adhesive samples cured under the same condition. The strength degradation of the bond for a certain temperature exposure is also reduced with increased Tg of the joint.