Adhesion improvement of carbon fibres by plasma treatment and evaluation by pull-out

Tuneable chemistry at the interface and self-healing towards improving structural properties of carbon fiber laminates: a critical review

Carbon fiber reinforced epoxy (CFRE) laminates have become a significant component in aircraft industries over the years due to their superior mechanical and highly tunable properties. However, the interfacial area between the fibers and the matrix continues to pose a significant challenge in debonding and delamination, leading to significant failures in such components. Therefore, since the advent of such laminated structures, researchers have worked on several interfacial modifications to better the mechanical properties and enhance such laminated systems' service life. These methods have primarily consisted of fiber sizing or matrix modifications, while effective fiber surface treatment has utilized the concept of surface energy to form an effective matrix locking mechanism. In recent times, with the advent of self-healing technology, research is being directed towards novel methods of self-healing interfacial modifications, which is a promising arena. In this review, we have provided comprehensive insight into the significance, historical advances, and latest developments of the interface of CFRE laminates. We have analysed the significant research work undertaken in recent years, which has shown a considerable shift in engineering the interface for mechanical property enhancement. Keeping in view the latest developments in self-healing technology, we have discussed reversible interfacial modifications and their impact on future improvements to service life.

Zeta Potential as a Tool to Characterize Plasma Oxidation of Carbon Fibers

Two different types of carbon fibers (ultrahigh modulus and high strength carbon fibers) were surface-treated in an oxygen plasma under equivalent conditions. Changes in the fiber surface chemistry were followed by electrokinetic measurements (zeta potential). The oxygen plasma treatment resulted in a displacement of the isoelectric point of carbon fibers toward lower pHs, evidence of an increase in the surface acidity. The possible simultaneous formation of basic functional groups was also inferred and supported by results obtained by inverse gas chromatography and wettability measurements. Differences were more evident with ultrahigh modulus carbon fibers than with high strength carbon fibers. It is concluded that the measurement of the electrokinetic properties constitutes a useful technique to follow the evolution of the surface chemical characteristics of different types of carbon fibers. Copyright 1997Academic Press