Strong and Stiff Aramid Nanofiber/Carbon Nanotube Nanocomposites

Abstract

Small but strong carbon nanotubes (CNTs) are fillers of choice for composite reinforcement owing to their extraordinary modulus and strength. However, the mechanical properties of the nanocomposites are still much below those for mechanical parameters of individual nanotubes. The gap between the expectation and experimental results arises not only from imperfect dispersion and poor load transfer but also from the unavailability of strong polymers that can be effectively utilized within the composites of nanotubes. Aramid nanofibers (ANFs) with analogous morphological features to nanotubes represent a potential choice to complement nanotubes given their intrinsic high mechanical performance and the dispersible nature, which enables solvent-based processing methods. In this work, we showed that composite films made from ANFs and multiwalled CNTs (MWCNTs) by vacuum-assisted flocculation and vacuum-assisted layer-by-layer assembly exhibited high ultimate strength of up to 383 MPa and Young's modulus (stiffness) of up to 35 GPa, which represent the highest values among all the reported random CNT nanocomposites. Detailed studies using different imaging and spectroscopic characterizations suggested that the multiple interfacial interactions between nanotubes and ANFs including hydrogen bonding and π-π stacking are likely the key parameters responsible for the observed mechanical improvement. Importantly, our studies further revealed the attractive thermomechanical characteristics of these nanocomposites with high thermal stability (up to 520 °C) and ultralow coefficients of thermal expansion (2-6 ppm·K(-1)). Our results indicated that ANFs are promising nanoscale building blocks for functional ultrastrong and stiff materials potentially extendable to nanocomposites based on other nanoscale fillers.

Grafting carbon nanotubes directly onto carbon fibers for superior mechanical stability: Towards next generation aerospace composites and energy storage applications

“…The grafting of CNTs on CF was further assessed by analyzing the Raman spectra of the as received CF, oxidized CNT and CNT grafted on CF samples as shown in Figure S3. For CF, oxidized CNT and CNT grafted on CF samples, the signals corresponding to D and G bands occur at 1370, 1343 and 1348 cm −1 and 1587, 1604 and 1572 cm −1 , respectively, which is possibly associated with disordered and graphitized carbon, respectively [17][18][19]. The relatively high intensity of the D band for the CNT−grafted carbon fiber sample than that of CF sample,…”

High Strength Conductive Composites with Plasmonic Nanoparticles Aligned on Aramid Nanofibers

“…Here we describe the possibility to prepare a free standing flexible composite material with these parameters made from prototypical metal NPs and aramid nanofibers (ANFs) . The latter represent a versatile new building block among nanomaterials and were chosen because ANFs inherits from the parent Kevlar nanofibers high chemical/thermal stability and exceptional mechanical performance (stiffness: 109 GPa and strength: 3.6 GPa), high nanoscale porosity of ANF matrixes, and the abundance of surface amide groups on ANFs enables further functionalization of the nanofibers and incorporation of other components onto and between aramid chains . Also importantly production of ANFs is easy to scale.…”

Tailoring the structure of Kevlar nanofiber and its effects on the mechanical property and thermal stability of carboxylated acrylonitrile butadiene rubber

“…In the spectrum of unfilled XNBR, there only appears a broad characteristic peak at 2θ = 18.7°, corresponding to the amorphous structure of XNBR . For ANFs, the characteristic peaks at around 20.6, 23.1, and 28.5° correspond to (110), (200), and (004) lattice planes, respectively . The observed diffraction peaks of hANFs are similar to those of ANFs, which indicate the reservation of the crystalline structures of PPTA in the nanoscale domains after acid hydrolysis.…”