Designable “Soft‐Hard” Dual‐Network Interface Engineering for Tailoring Both Interfacial and Interlaminar Properties in Glass Fiber Fabric/Epoxy Laminated Composites

ABSTRACT Fiber‐reinforced epoxy composites are susceptible to interfacial debonding and delamination during service, which significantly reduces their service life. This study reports an effective strategy to simultaneously enhance both interfacial and interlaminar properties in glass fiber‐reinforced laminated composites by constructing a “soft‐hard” dual‐network structure on the fiber surface. Specifically, the soft‐segment methoxy polyethylene glycol (mPEG) was grafted onto the surface of rigid carbon nanotubes (CNTs) via a “click chemistry” reaction. The resulting modified carbon nanotubes (mPEG‐CNTs) were uniformly deposited on the surface of glass fiber fabrics. Glass fiber reinforced epoxy (GFRE) laminates were subsequently fabricated using vacuum‐assisted resin infusion molding (VARIM). The results demonstrated that soft‐segment mPEG improved the dispersion of CNTs on the fiber surface. In addition, mPEG could form a semi‐interpenetrating network (semi‐IPN) with epoxy matrix, thereby enhancing the fiber/matrix interfacial adhesion. The combination of soft‐segment mPEG and hard‐segment CNTs enhanced stress transfer from the fiber and matrix, which effectively suppressed crack initiation and propagation in the interfacial region. At an optimal mPEG‐CNTs concentration of 1.5 g/L, the laminated composites achieved maximum flexural strength and modulus (42.1% and 33.4% higher than pure GFRE, respectively). The interlaminar shear strength and work of fracture also reached the maximum values, increasing by 41.0% and 161.2%, respectively, compared to pure GFRE.