Advanced Epoxy Polymer Composite Design: Maximizing Fracture Toughness and Piezoelectric Effect with Core–Shell Rubber and Barium Titanate Particles

Epoxy resins, when cured are important thermoset polymers which possess exceptional bonding strength, versatility, and resistance, making them indispensable in various industries ranging from construction to electronics. This study aims to investigate epoxy-based polymer composites with varying core–shell rubber (CSR) fractions (0–5–10–15–25 wt %) with a fixed weight percentage (20 wt %) of barium titanate (BaTiO₃) and tailor the thermal, mechanical and piezoelectric behavior of the resulting materials. Tensile, single lap shear and T-Peel strength tests were conducted to evaluate the effects of CSR and BaTiO₃ additives on the mechanical properties of the composites. Fracture toughness and fracture energy measurements were performed using the single-edge notched bend test to assess the crack resistance of the composites. The thermal-mechanical properties of the composites were analyzed using a dynamic mechanical analyzer. A voltage output test was performed to evaluate the piezoelectric properties of the composites. The results demonstrated that with 5 wt % CSR incorporation, the composite exhibited a remarkable increase in fracture energy, increasing from 465 to 2213 J/m², and with 15 wt % CSR addition, the highest open circuit voltage output of 1.85 V was obtained.