Microscopic Fracture Behavior and Thermal‐Mechanical Properties of Biowaste‐Modified <scp>CaCO₃</scp>/<scp>rGO</scp>‐Carbon Fiber Epoxy Composites for Structural Applications

ABSTRACT Carbon fiber‐reinforced polymer (CFRP) composites have gained significant attention for their lightweight and excellent mechanical properties; however, pure epoxy resins alone cannot meet the demands of high‐performance composites. The influence of (CaCO 3 /rGO) CACG‐based hybrid filler on CFRP composites' thermal and mechanical properties was systematically investigated. Fracture analysis was performed using an in situ notch tensile test in a field emission scanning electron microscope. At the same time, finite element analysis was employed to predict the stress distribution in each ply. The CACG3/CFRP (1 wt% loading of GO) composite showed higher mechanical, viscoelastic, and thermal properties compared to other composites, with tensile and flexural strength enhancements of ~45.33% and 76.17%, respectively. Incorporating the hybrid nanofiller significantly improved the composites' glass transition temperature ( T g ) and thermal stability. This study provided valuable insights into the design and development of structural‐functional CFRP composites, paving the way for their potential applications in aerospace and other high‐performance engineering fields.