Mitigating Saline Degradation and Enhancing Tensile Performance in CFRP Laminates Using Graphene-CNT Hybrid Nanoparticles

Carbon fiber reinforced polymer (CFRP) composites, although frequently preferred in many fields where weight is critical due to their high specific strength, are susceptible to environmental degradation in marine conditions. The primary cause of this degradation is the ingress of moisture into the structure. This leads to significant swelling of the matrix and dimensional mismatches at the fiber-matrix interface. This study investigates the reduction of such saline degradation and the enhancement of tensile performance in CFRP laminates by modifying the epoxy matrix with a 0.5% by weight of graphene doped multi-walled carbon nanotube (MWCNT) hybrid nanoparticles. Nanoparticle modified CFRP laminates were produced and subjected to a 15-day salt spray aging treatment (5% NaCl, 35 °C). Under non-aged conditions, the addition of hybrid nanoparticles (CNT_N-A) significantly improved tensile performance, increasing the average tensile strength by 7.98% compared to the neat reference (REF_N-A) configuration. After salt spray exposure, the modified laminates (CNT_A) exhibited 3.90% moisture absorption, which led to a decrease in tensile strength (6.11%) due to matrix plasticization. Nevertheless, the aged modified composites performed better than the non-aged neat CFRP, exhibiting a 1.38% higher tensile strength. These findings highlight the promising potential of graphene-MWCNT hybrid nanoparticles in enhancing the environmental durability and load-bearing capacity of CFRP structures in harsh saline environments.