Design, Preparation, and Characterization of a Supported Epoxy Film Adhesive Reinforced by Core–Shell Rubber Particles for Aluminum–Aluminum Bonded Joints: Mechanical and Thermal Analysis

ABSTRACT This study addresses the brittleness and limited toughness of highly crosslinked epoxy film adhesives for high‐temperature use by incorporating phenolic resin (Novolac) and core–shell rubber (CSR) particles with a PMMA shell/butyl acrylate core. Adhesives with 20 phr phenolic resin and 1, 3, and 5 phr CSR were prepared. Mechanical, adhesion, and thermal properties were assessed via tensile, flexural, lap‐shear, and T‐peel tests, fracture surface analysis (FESEM), TGA, and DSC. Results showed that 3 phr CSR provided optimal enhancement. Tensile strength, flexural strength, and toughness increased by 57%, 24%, and 161%, respectively. Adhesion improved, with lap‐shear and T‐peel strengths rising by 26% and 81%. FESEM revealed toughening mechanisms like crack deflection and blunting. Thermal stability improved, with higher initial degradation temperatures and a lower curing temperature. In conclusion, phenolic resin and CSR particles synergistically improve epoxy adhesive performance. The 3 phr CSR formulation significantly enhances mechanical strength, adhesion, and thermal stability, making it promising for demanding high‐temperature industrial applications.