Direct visualization of interfacial debonding in FRP structure using an AIE molecule

Abstract Interfacial debonding is one of dominant damage types in fiber-reinforced polymers (FRPs). Therefore, monitoring the initiation and propagation of interfacial debonding in FRP is crucial for evaluating the health state of composites. The present work developed a direct visualization method using 1,1,2,2-tetrakis(4-nitrophenyl)ethene (TPE-4N) with aggregation-induced emission property, to detect the interfacial debonding in FRPs. To do so, TPE-4N was deposited on basalt fiber using dip-coating method, and the coated fiber was embedded into polydimethylsiloxane to fabricate corresponding composites. The results showed that TPE-4N molecule could correlate the invisible strain information in composites with the fluorescence signal under mechanical stimulus, and this could be quantitatively expressed by the grayscale value of materials. Interestingly, the debonding strain of composites (5.25%) obtained by the present method was much lower than the one (6.93%) obtained by the traditional strain measurement, suggesting that the fluorescence technique developed in this study was an effective way for in-situ and direct visualization of damage process in FRP structure.