Carbon nanotubes synthesized on the surface of recycled carbon fibers by catalytic chemical vapor deposition for revalorization of degraded composite materials

Abstract

There is a clear need to develop a sustainable use of composite materials; high-performance composite materials like carbon-epoxy systems are of special interest because of their wide range of applications and their high intrinsical value. Even though the technology for recycling thermoset composite materials has been developed, and the recovery of carbon fibers from composite materials is feasible, there is still to some extent, a degradation of the recovered carbon fibers; thus, a revalidation of the recycled carbon fibers with improved properties is highly desirable for a new life cycle in high-performance composites and components; thereupon, revalorization of the recovered carbon fibers by anchorage and growth of carbon nanotubes directly on the surface of the fibers via assembly of graphene-cap mechanism on nickel nanoparticles is an attractive technological approach for integral recycling of composite materials. These revalorized carbon fibers with carbon nanotubes are potential candidates for novel composites with exceptional mechanical, thermal, and electrical properties. In this research, catalytic chemical vapor deposition method was used for the synthesis of carbon nanotubes on the recycled fibers under influence of carbon source, temperature. Carbon nanotubes were produced by decomposing whether ethanol or isopropanol as a carbon source at temperatures ranging from 800 to 600 °C in an inert atmosphere. Fibers used as a substrate in this research are actually recovered carbon fibers from a carbon-epoxy composite component reaching end-of-life via pyrolysis. All experimental results were characterized using scanning electron microscopy corroborating the synthesis and morphology of the carbon nanotubes on the carbon fibers; Raman spectroscopy corroborated synthesis of multiwall carbon nanotubes; pseudo-mechanical testing confirmed that the nanotubes have a good anchorage to the carbon fiber surface, making this novel revalorized fiber a potential reinforcement for new high-performance composite materials.