On the interaction between the carbon fiber surface and the epoxy resin matrix in carbon fiber reinforced polymers
- Interactions at molecular-, nano-, and microscales determine the mechanical performance of a fiber reinforced composite at the macroscale. A fundamental understanding of adhesion mechanisms is required to optimize fiber-matrix bonding and, in turn, the composite´s mechanical properties. This work comprehensively investigates the interactions between carbon fibers and epoxy resin in carbon fiber reinforced polymers. The effects of carbon fiber surface treatment on fiber-matrix adhesion were investigated using a single well-known type of carbon fiber. Oxygen functionalization by anodic oxidation treatment and nitrogen functionalization by ammonia plasma treatment were performed. In addition, an organosilicon layer was deposited by plasma treatment using the precursor gas methyltrimethoxysilane. For commercial carbon fibers, an important factor in fiber-matrix adhesion is the interaction between the functionalized carbon fiber surface and the polymeric sizing layer. Consequently, theInteractions at molecular-, nano-, and microscales determine the mechanical performance of a fiber reinforced composite at the macroscale. A fundamental understanding of adhesion mechanisms is required to optimize fiber-matrix bonding and, in turn, the composite´s mechanical properties. This work comprehensively investigates the interactions between carbon fibers and epoxy resin in carbon fiber reinforced polymers. The effects of carbon fiber surface treatment on fiber-matrix adhesion were investigated using a single well-known type of carbon fiber. Oxygen functionalization by anodic oxidation treatment and nitrogen functionalization by ammonia plasma treatment were performed. In addition, an organosilicon layer was deposited by plasma treatment using the precursor gas methyltrimethoxysilane. For commercial carbon fibers, an important factor in fiber-matrix adhesion is the interaction between the functionalized carbon fiber surface and the polymeric sizing layer. Consequently, the effects of the reactivity of epoxy-based sizings were also explored. Finally, the interaction between the functionalized, sized carbon fibers and the epoxy resin matrix was investigated. The influence of the matrix polymer on fiber-matrix bonding was elucidated by using both a fast-curing bifunctional and a slow-curing tetrafunctional amine-hardened epoxy resin. The results demonstrate that fiber-matrix adhesion in carbon fiber reinforced polymers can be tailored by making defined adjustments of the physical and chemical properties of the fiber surface, significantly surpassing the current state of the literature and technology. This investigation reveals the important role of the delicate interplay among fiber surface functionalization, polymeric sizing, and the epoxy resin matrix in determining composite properties.…
