Multifunctional composites using reinforced laminae with carbon-nanotube forests

Abstract

Traditional fibre-reinforced composite materials with excellent in-plane properties fare poorly when out-of-plane through-thickness properties are important. Composite architectures with fibres designed orthogonal to the two-dimensional (2D) layout in traditional composites could alleviate this weakness in the transverse direction, but all of the efforts so far have only produced limited success. Here, we unveil an approach to the 3D composite challenge, without altering the 2D stack design, on the basis of the concept of interlaminar carbon-nanotube forests that would provide enhanced multifunctional properties along the thickness direction. The carbon-nanotube forests allow the fastening of adjacent plies in the 3D composite. We grow multiwalled carbon nanotubes on the surface of micro-fibre fabric cloth layouts, normal to the fibre lengths, resulting in a 3D effect between plies under loading. These nanotube-coated fabric cloths serve as building blocks for the multilayered 3D composites, with the nanotube forests providing much-needed interlaminar strength and toughness under various loading conditions. For the fabricated 3D composites with nanotube forests, we demonstrate remarkable improvements in the interlaminar fracture toughness, hardness, delamination resistance, in-plane mechanical properties, damping, thermoelastic behaviour, and thermal and electrical conductivities making these structures truly multifunctional.

Development of sizing-free multi-functional carbon fibre nanocomposites

“…The F-CFRP and, to a lesser degree, the CFRP displays decreasing fracture toughness with respect to crack length, whereas the SR-CFRP data displays stable behaviour Typically, for fracture toughness testing, the initial values and propagation values at steady state are compared. Veedu et al [54] opted to compare only the initial fracture toughness values of their SiC fibres (plain weave) modified with CNTs, stating that these initiation values represent the generic fracture toughness and Prel et al [55] suggested that initiation values for fracture toughness are independent of sample thickness. Garcia et al [56] also observed reduction in fracture toughness with crack length for their CNT-modified samples and attributed this to the discontinuous placement of CNTs on the cross ply (although this is not the case in the present work, see Figure 2).…”

“Self‐Peel‐Off” Transfer Produces Ultrathin Polyvinylidene‐Fluoride‐Based Flexible Nanodevices

“…PVDF experiences high deformations when subjected to changes in temperature due to its high coefficient of thermal expansion (CTE, α = 127 × 10 −6 K −1 ), which easily generates internal stress in laminated films containing a PVDF layer 21. Carbon materials (e.g., single‐walled carbon nanotube (SWCNT), graphene oxide (GO)) have negative CTEs (α = −1.5 × 10 −6 and −67 × 10 −6 K −1 , respectively), which means that these materials contract whereas PVDF expands when the environmental temperature increases 22. As far as moisture absorption is concerned, both PVDF and carbon material expand when they take up water 23.…”

Nonlinear viscoelasticity of freestanding and polymer-anchored vertically aligned carbon nanotube foams

“…Examples include 1D flexible yarns, 5,6 2D sheets, 7 3D "mats" or "forests" of aligned CNTs, [8][9][10] and disordered structures. 11 These systems have been suggested for several applications, including electronic 11,12 and field emission devices, 13 composites, 14,15 and bioactive materials. 16,17 The partial anchoring of vertical arrays of carbon nanotubes (VACNTs) in a single, thin polymer film has been previously reported, 18,19 and the mechanical response of anchored VACNTs has been characterized under quasi-static compressive loading.…”