Study on the toughening of epoxy resin modified by multi‐component fillers of carbon nanofibers/nano‐silica/short carbon fibers

Abstract The present study investigates the effects of carbon nanofibers (CNF), nano‐silica (SiO ₂ ) and short carbon fibers (SCF) on the tensile strength and fracture toughness of cured epoxy resins. The damage patterns exhibited by the modified epoxy resin specimens were analyzed using the acoustic emission (AE) technique during fracture toughness tests. The digital image correlation (DIC) technique was employed to monitor the evolution of the strain field on the specimen surface. Scanning electron microscopy (SEM) was used to observe the fractured surface of the specimens to analyze the toughening mechanism. The experimental findings demonstrated that the tensile strength of the epoxy resin attained its maximum when blended with two fillers, 1.0 wt.% CNF and 0.5 wt.% SiO ₂ , resulting in an enhancement of 11.71%. The elongation of the material was maximized when blending epoxy resin with three fillers: 1 wt.% CNF, 0.5 wt.% SiO ₂ , and 0.5 wt.% SCF, resulting in a 6.6% increase in tensile strength. In the single edge notched tensile (SENT) test, the critical strain energy release rate ( G _IC ) exhibited a 24.41% increase, representing the most substantial increase observed. In the single edge notched bending (SENB) test, the G _IC was significantly increased by 51.51%, indicating its excellent mechanical properties and fracture toughness. Highlights Research on the synergistic toughening of epoxy resin by multi‐scale fillers: CNF, SiO2, and SCF. AE and DIC were used to analyze the damage evolution of the epoxy resins/composites during the fracture toughness test. SEM was used to analyze the toughening mechanism of the epoxy resins/composites.