Hierarchical Composites Reinforced with Carbon Nanotube Grafted Fibers: The Potential Assessed at the Single Fiber Level

Abstract

The feasibility of reinforcing conventional carbon fiber composites by grafting carbon nanotubes (CNTs) onto the fiber surface has been investigated. Carbon nanotubes were grown on carbon fibers using the chemical vapor deposition (CVD) method. Iron was selected as the catalyst and predeposited using the incipient wetness technique before the growth reaction. The morphology of the products was characterized using scanning electron microscopy (SEM), which showed evidence of a uniform coating of CNTs on the fiber surface. Contact angle measurements on individual fibers, before and after the CNT growth, demonstrated a change in wettability that can be linked to a change of the polarity of the modified surface. Model composites based on CNT-grafted carbon fibers/epoxy were fabricated in order to examine apparent interfacial shear strength (IFSS). A dramatic improvement in IFSS over carbon fiber/epoxy composites was observed in the single fiber pull-out tests, but no significant change was shown in the push-out tests. The different IFSS results were provisionally attributed to a change of failure mechanism between the two types of tests, supported by fractographic analysis.

Development of sizing-free multi-functional carbon fibre nanocomposites

“…As the tensile load is transmitted in the outer skins of the carbon fibre, the tensile performance of the composite will be sensitive to any modifications to the outer layer of the carbon fibre [39]. It is well documented that growing CNTs via CVD reduces the tensile performance of the fibres and given the composite tensile test is fibre dominated, the SR-CFRP at GT will state this reduction [15]. The F-CFRP displayed a 33 % reduction in the σUTS compared to the CFRP, suggesting additional degradation from the CNTs (as the SR-CFRP at GT displayed an 11% degradation).…”

Carbon Fiber-Reinforced Polyurethane Composites with Modified Carbon–Polymer Interface

“…Delamination, in turn, is determined by weak CF-to-matrix binding. This weak CF-to-matrix binding maybe improved and a better interfacial shear strength (IFSS) maybe reached through the control of the fiber-matrix interface [1,2].…”

Carbon nanotube grafted silica fibres: Characterising the interface at the single fibre level

“…An improvement of interfacial load transfer was subsequently reported by grafting CNTs on carbon fibres [17]. More recently, a 60% improvement of IFSS was observed for the CNT-grafted carbon fibres/epoxy composites [18]. Although some promising results have been obtained, a better understanding is required of the critical factors that determine the composite interfacial properties, such as the surface area, fibre wettability, and CNT dimensions.…”

“…CVD is also the most common method for grafting CNTs onto fibre surfaces [17][18][19][20][21][22]. In the present study, a simple injection chemical vapour deposition (ICVD) method was used to grow CNTs on silica fibres; CNT-grafting with different lengths was produced by varying the growth time.…”