Rigid-flexible interface improves carbon fiber/epoxy performance
Researchers have developed a new interface that improves the interlaminar strength of carbon fibre/epoxy composites, as reported in Progress in Organic Coatings.
A novel "rigid-flexible" interface design, combining lignin-based epoxy resin with nano-cerium oxide sol, significantly enhances the mechanical performance of carbon fibre/epoxy composites. This approach increased interlaminar shear strength by 55%, flexural strength by 95%, and tensile strength by 67%, while utilizing renewable lignin as an eco-friendly alternative to petroleum-based modifiers.
The interface between carbon fibres and the resin matrix is crucial for the mechanical performance of fibre-reinforced composites. To optimize stress distribution and load transfer efficiency, researchers developed a "rigid-flexible hybrid" interface design strategy. This combines flexible lignin-based epoxy resin (LBEP) with rigid nano-cerium oxide sol (CeO₂). The synergistic effect of these components improves both the wettability and surface roughness of the carbon fibres, enhancing interfacial adhesion with the epoxy matrix.
Rigid CeO₂ particles are uniformly distributed across the interface, enhancing mechanical interlocking and load-bearing capacity through physical anchoring and crack deflection mechanisms. The flexible LBEP acts as a multifunctional bridging phase, forming stable covalent bonds with both the carbon fibre surfaces and the surrounding resin matrix. It mitigates stress concentration through molecular chain conformation adjustment and energy dissipation.
Experimental results demonstrate the effectiveness of this approach: carbon fibre/epoxy composites with the modified interface showed a 55% increase in interlaminar shear strength, a 95% increase in flexural strength, and a 67% increase in tensile strength compared to unmodified systems. The multi-level interfacial structure integrates high strength with high toughness, enabling efficient stress transfer and energy dissipation under load.
Beyond mechanical improvements, the strategy offers sustainability benefits. Using lignin, a renewable and abundant raw material, as the basis for the flexible epoxy component provides an eco-friendly alternative to conventional petroleum-based modifiers. Combined with a relatively simple processing route, this method is a promising interfacial engineering strategy for developing high-performance carbon fibre composites in demanding applications.
Source: Carbon Fiber Feed