Effects of liquid rubber-modified epoxy on the fracture toughness of rGO-Coated fabric piezoresistive composites

In this study, a reduced graphene oxide (rGO)-coated glass fabric-based piezoresistive composite with enhanced fracture toughness was developed using a liquid rubber-modified epoxy system. Carboxyl-terminated butadiene acrylonitrile copolymer (CTBN)-modified epoxy was infused into the composite via the vacuum-assisted resin transfer molding (VARTM) process, embedding the partially reduced rGO-coated glass fabric. The electromechanical performance of the composite, tested under tensile, Mode I, and Mode II conditions, was compared to unmodified epoxy-based samples. The results demonstrated a significant improvement in the interlaminar fracture toughness of the CTBN-modified epoxy samples without affecting the piezoresistive sensitivity. Specifically, adding 10 wt% of CTBN to the epoxy led to a ∼38 % increase in Mode I fracture toughness and a ∼16 % increase in Mode II fracture toughness. However, a 5 % decrease in elastic modulus was observed during tensile testing. Additionally, the CTBN-modified epoxy samples exhibited higher tensile strain at failure compared to the unmodified samples, indicating enhanced ductility due to the addition of CTBN. Scanning electron microscopy (SEM) images confirmed the highly deformed, ductile nature of the fractured surfaces in the CTBN-modified samples.