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.
Asl et al. (Fri,) studied this question.