The Influence of CNF / SiO ₂ / SCF Additives on Interlaminar Toughening of Glass Fiber/Epoxy Laminates

ABSTRACT Fiber‐reinforced composite materials are susceptible to delamination failure and inadequate interlaminar performance, owing to the absence of fiber reinforcement in the thickness direction and the low fracture toughness of the polymer matrix. The present study employs carbon nanofibers (CNF), nano‐silica (SiO ₂ ), and short carbon fibers (SCF) as multi‐scale fillers to enhance interlaminar toughness in glass fiber‐reinforced composites. To achieve this objective, a series of double cantilever beam (DCB) and end‐notched flexure (ENF) tests were conducted with the purpose of measuring mode‐I interlaminar fracture toughness ( G _IC ) and mode‐II interlaminar fracture toughness ( G _IIC ). The damage and toughening mechanisms were analyzed using acoustic emission (AE) and scanning electron microscopy (SEM) techniques. The experimental findings suggest that, among the single fillers, SCF demonstrates a more substantial toughening effect. The combination of 0.5 wt.% CNF, 0.5 wt.% SiO ₂ , and 0.5 wt.% SCF resulted in a substantial enhancement of the interlaminar fracture toughness of the composite material; the G _IC increased by 74.4%. Similarly, the G _IIC increased by 34.7%. The toughening effect of the multi‐scale filler combination is significantly higher than that of a single filler. The combination of the three fillers produces a synergistic toughening effect, absorbing more fracture energy and significantly improving resistance to delamination.