Adhesion and Hydrothermal Performance of Epoxy–Dicyandiamide Adhesive Film for PMMA-PETR

Epoxy/dicyandiamide adhesive film is required for the bonding of polymethyl methacrylate (PMMA) aircraft cockpit edges. An imidazole/alkanolamine composite accelerator was developed to satisfy the requirement of maintaining a bonding temperature below 90 °C for this structure, successfully reducing the curing temperature of the adhesive film from 180 °C to 85 °C. The curing process of the low-temperature curing adhesive film and its hydrothermal aging resistance after curing were investigated using mechanical testing, Fourier transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). The results indicate that the curing process of 85 °C for 6 h enables the adhesive film to fulfill the adhesion strength requirements for aircraft cockpit edge applications. The cured adhesive film is found to exhibit limited intrinsic water resistance due to its low crosslinking density. Therefore, external edge sealing is required in practical engineering applications to isolate moisture. This work provides an application-specific one-component epoxy/dicyandiamide adhesive film for the low-temperature flexible bonding of aviation PMMA cockpit edges to PETR, and clarifies its adhesion performance and hydrothermal aging behavior under the target service scenario.