24 results found
Lee WJ, Clancy AJ, Fernández-Toribio JC, et al., 2019, Interfacially-grafted single wall carbon nanotube / poly (vinyl alcohol) composite fibers, Carbon, Vol: 146, Pages: 162-171, ISSN: 0008-6223
© 2019 Nanocomposites are critically influenced by interfacial interactions between the reinforcement and matrix. Polyvinyl alcohol (PVOH) of varying molecular weights were prepared and grafted-to single-walled carbon nanotubes (SWCNTs), to improve the interfacial interaction with a homopolymer PVOH matrix. Nanocomposite fibers were coagulation spun across a broad range of loading fractions, controlled by the spinning dope composition. An intermediate grafted-PVOH molecular weight (10 kDa) maximized grafting ratio, and the final composite mechanical performance; the positive effects were attributed to the increased degree of dispersion of the SWCNTs in the dope, as well as the favorable interface. The PVOH grafting increased the stability of the SWCNT loading fractions (up to 45 wt.%), offering increased strength (up to 1100 MPa) and stiffness (up to 38.5 GPa); at the same time, strain-to-failures remained high (up to 23.3%), resulting in high toughness (up to 125 J g −1 ).
Clancy A, Sirisinudomkit P, Anthony D, et al., 2019, Real-time mechanistic study of carbon nanotube anion functionalisation through open circuit voltammetry, Chemical Science, ISSN: 2041-6520
The mechanism of the functionalisation of reduced single walled carbon nanotubes with organobromides was monitored byopen circuit voltammetry throughout the reaction and further elucidated through a series of comparative reactions. Thedegree of functionalisation was mapped against the reagent reduction potential, degree of electron donation of substituents(Hammett parameter), and energies calculated, ab initio, for dissociation and heterolytic cleavage of the C-Br bond. Incontrast to the previously assumed reduction/homolytic cleavage mechanism, the reaction was shown to consist of a rapidassociation of carbon-halide bond to the reduced nanotube as a complex, displacing surface-condensed countercations,leading to an initial increase in the net nanotube surface negative charge. The complex subsequently slowly degradesthrough charge transfer from the reduced single-walled carbon nanotube to the organobromide, utilizing charge, and thecarbon-halide bond breaks heterolytically. Electron density on the C-Br bond in the initial reagent is the best predictor fordegree of functionalisation, with more electron donating substituents increasing the degree of functionalisation. Both themechanism and the new application of OCV to study such reactions are potentially relevant to wide range of related systems.
Clancy A, Anthony DB, Shaffer M, 2019, Reactive coagulation of single-walled carbon nanotubes for tougher composites – solution processing and assembly, Polymer Processing Society Europe Africa Conference 2017 (PPS 2017) with 7th International Conference on Carbon NanoParticle Based Composites (CNPComp2017), Publisher: AIP Publishing, Pages: 090005-090005, ISSN: 1551-7616
The injection of reduced single-walled carbon nanotubes into a coagulation bath of polyvinyl chloride (PVC) solution leads to the formation of nanocomposite fibres with polymer covalently bound to the nanotubes. The influence of PVC concentration and molecular weight, and the extrusion diameter on the nanocomposite fibre tensile properties and composition have been examined. The nanocomposite fibres produced have strengths as high as 480 MPa and modulus of 15 GPa, making them the strongest and stiffest PVC composites recorded to date.
Liu B, Liu C, De Luca H, et al., 2019, Synthesis of epoxidized poly(ester carbonate)-b-polyimide-b-poly(ester carbonate): reactive single-walled carbon nanotube dispersants enable synergistic reinforcement around multi-walled nanotube-grafted carbon fibers, Polymer Chemistry, ISSN: 1759-9954
Polyimides (PI) generally have a high affinity for single-walled carbon nanotubes (SWNTs), but they suffer from poor solubility in most low boiling point organic solvents and low compatibility with common resins (such as epoxy) used in composites, limiting their suitability as dispersants. PI block copolymer systems containing reactive poly(ester carbonate)s have not yet been reported and are expected to act as effective reactive dispersing agents of SWNTs. Herein, PI-derived block copolymers are synthesized via ring-opening copolymerization of lactide (LA) (a control monomer) and allyl-bearing 2-methyl-2-(allyloxycarbonyl)-propylene carbonate (MAC) from the OH-terminal ends of the PI block to produce PLA-PI-PLA (TB1, a control) and PMAC-PI-PMAC (TB2). The allyl pendant group of TB2 allows further facile functionalization to form a third series of epoxidized (EP) derivatives, i.e. PMACEP-block-PI-block-PMACEP (TB3). TB3 copolymer when mixed with a conventional structural epoxy resin forms blends that do not show inferior tensile properties compared with the epoxy, which is unusual. Furthermore, the mixing solvent tetrahydrofuran (THF) can be readily evaporated off after forming the blends. TB3-dispersed (2 wt%) SWNTs added to epoxy increased the tensile strength, modulus, and elongation at break of the resulting nanocomposite films by 40%, 34%, and 26% respectively, compared to the baseline epoxy resin. Furthermore, when TB3b triblock-dispersed SWNTs in epoxy were combined with fuzzy carbon fibers, i.e. carbon nanotube-grafted-carbon fibers (CNT-g-CF), a synergistic interfacial strength reinforcement was observed, together with shifting of the failure mode from the matrix interphase to the carbon fiber-grafted nanotube interface. The ultimate interfacial shear strength between the TB3-dispersed SWNT-epoxy matrix and the fuzzy carbon fibers (i.e., fibers having carbon nanotubes grown on them) measured via single fiber pull-out tests was 100 MPa, which was ca. 11% imp
Anthony DB, Sui X, Kellersztein I, et al., 2018, Continuous carbon nanotube synthesis on charged carbon fibers, COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING, Vol: 112, Pages: 525-538, ISSN: 1359-835X
Anthony DB, Bacarreza Nogales O, Shaffer M, et al., Pseudo-ductile failure mechanism introduced into finger jointed thermoplastic PES interleaved CFRC, ECCM18 - 18th European Conference on Composite Materials
Pre-cut unidirectional carbon fibre prepreg composites, with an overlapped finger-joint architecture, were modified through the addition of polyethersulfone (PES) interleaves. The properties arising from these finger-jointed configurations were strongly dependent on the interply overlap region. When the tough thermoplastic interleaves spanned only the central portion of the overlap, a crack arresting failure mechanism was observed in tension. A pronounced plateau region or pseudo-ductile response was shown in conjunction with a strain hardening response after crack arrest. The local strain-to-failure of PES interleaved samples was ~3.2%, an increase of 85% compared to the pre-cut baseline (strain-to-failure 1.6%, pre-cut specimens without interleaves).
De Luca F, Clancy AJ, Carrero NR, et al., 2018, Increasing carbon fiber composite strength with a nanostructured "brick-and-mortar" interphase, MATERIALS HORIZONS, Vol: 5, Pages: 668-674, ISSN: 2051-6347
Woodward RT, Markoulidis F, De Luca F, et al., 2018, Carbon foams from emulsion-templated reduced graphene oxide polymer composites: electrodes for supercapacitor devices, JOURNAL OF MATERIALS CHEMISTRY A, Vol: 6, Pages: 1840-1849, ISSN: 2050-7488
Buckley DJ, Hodge SA, De Marco M, et al., 2017, Trajectory of the Selective Dissolution of Charged Single-Walled Carbon Nanotubes, JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 121, Pages: 21703-21712, ISSN: 1932-7447
Anthony DB, Qian H, Clancy AJ, et al., 2017, Applying a potential difference to minimise damage to carbon fibres during carbon nanotube grafting by chemical vapour deposition, NANOTECHNOLOGY, Vol: 28, ISSN: 0957-4484
Clancy AJ, Anthony DB, Fisher SJ, et al., 2017, Reductive dissolution of supergrowth carbon nanotubes for tougher nanocomposites by reactive coagulation spinning, NANOSCALE, Vol: 9, Pages: 8764-8773, ISSN: 2040-3364
Woodward RT, Jobbe-Duval A, Marchesini S, et al., 2017, Hypercrosslinked polyHIPEs as precursors to designable, hierarchically porous carbon foams, POLYMER, Vol: 115, Pages: 146-153, ISSN: 0032-3861
Anthony DB, Nogales ORB, Shaffer MSP, et al., 2017, Crack arrest in finger jointed thermoplastic pes interleaved CFRC
© 2017 International Committee on Composite Materials. All rights reserved. Pre-cut unidirectional carbon fibre prepreg (M21/194/34%/T800S) composites were tested in tension with a 20 mm overlapped finger joint architectures. In between the overlapping finger jointed region the effect of introducing polyethersulfone (PES) interleaves is investigated. Samples with the addition of a thick PES interleave arrested the initial crack which formed at the pre-cut site. The strain-to-failure of the thick PES interleaved samples was over 3.2%, an increase of 85% compared to the baseline samples, and catastrophic failure was delayed in the majority of instances.
De Luca H, Anthony DB, Greenhalgh ES, et al., 2017, Continuous production of carbon nanotube-grafted quartz fibres: Effect of carbon nanotube length on fibre/matrix adhesion
© 2017 International Committee on Composite Materials. All rights reserved. Here, the continuous production of carbon nanotube-grafted-quartz-fibres was performed in an open chemical vapour deposition reactor with continuous in line catalyst deposition. Highly graphitic carbon nanotubes (CNTs) with controllable lengths ranging from 0.1 µm to 20 µm were grown on the quartz fibre surface by adjusting the reduction and growth times, with shorter fibres growing homogeneously and longer CNTs growing in a splayed “Mohawk” manner. The effect of CNTs length (and thus microstructure) upon the mechanical properties of CNT-grafted-quartz-fibre/epoxy composites was investigated through single fibre pull-out test. The presence of a uniform coverage of sub-micron long CNTs led to an increase in interfacial shear strength of 11% and 29% when compared to sized and de-sized quartz fibres, respectively.
Blaker JJ, Anthony DB, Tang G, et al., 2016, Property and Shape Modulation of Carbon Fibers Using Lasers, ACS APPLIED MATERIALS & INTERFACES, Vol: 8, Pages: 16351-16358, ISSN: 1944-8244
Woodward RT, Fam DWH, Anthony DB, et al., 2016, Hierarchically porous carbon foams from pickering high internal phase emulsions, CARBON, Vol: 101, Pages: 253-260, ISSN: 0008-6223
Anthony DB, Shaffer MSP, 2016, Process for producing carbon-nanotube grafted substrate, WO 2016009207 A1
The present invention relates to a process for producing a carbon nanotube-grafted substrate, the process comprising: providing a substrate having catalytic material deposited thereon; and synthesising carbon nanotubes on the substrate by a chemical vapour deposition process in a reaction chamber; characterised in that the process comprises providing a counter electrode, applying a potential difference to the substrate in relation to the counter electrode and maintaining the potential difference of the substrate in relation to the counter electrode during the chemical vapour deposition process.
Anthony DB, Grail G, Bismarck A, et al., 2016, Exploring the tensile response in small carbon fibre composite bundles
© 2016, European Conference on Composite Materials, ECCM. All rights reserved.Small composite bundles, AS4 carbon fibre epoxy, with a restricted number of reinforcing fibres, ca. 20, showed a progressive failure when tested in tension. In-situ acoustic emission observations under tensile load reveal that numerous fibres fail before ultimate failure of the small composite bundle, suggesting that isolated and individual fibre failures occur without compromising the integrity of the neighboring fibres or the small composite bundle's overall mechanical performance. The average strength of the carbon fibres in small composite bundles was 9.6% higher than in standard lab-scale composite specimens using the same fibre type.
Bismarck A, Blaker JJ, Anthony DB, et al., 2016, Development of novel composites through fibre and interface/interphase modification, 37th Riso International Symposium on Materials Science - Understanding Performance of Composite Materials - Mechanisms Controlling Properties, Publisher: IOP PUBLISHING LTD, ISSN: 1757-8981
De Luca H, Anthony DB, Qian H, et al., 2016, Non-damaging and scalable carbon nanotube synthesis on carbon fibres
© 2016, European Conference on Composite Materials, ECCM. All rights reserved.The growth of carbon nanotubes (CNTs) on carbon fibres (CFs) to produce a hierarchical fibre with two differing reinforcement length scales, in this instance nanometre and micrometre respectively, is considered a route to improve current state-of-the-art fibre reinforced composites . The scalable production of carbon nanotube-grafted-carbon fibres (CNT-g-CFs) has been limited due to high temperatures, the use of flammable gases and the requirement of inert conditions for CNT synthesis, whist (ideally) maintaining underlying original substrate mechanical properties. Here, the continuous production of CNT-g-CF is demonstrated in an open chemical vapour deposition (CVD) reactor, crucially, whilst retaining the tensile properties of the carbon fibres. As synthesised CNTs have a diameter of sub 20 nm and length ca. 120 nm, which are predicted to provide ideal fibre reinforcement in composites by retaining optimal composite fibre volume fraction (60%), whilst improving interfacial bonding of the matrix and reinforcement [1, 2]. Mild processing techniques enable this modified CVD process to be fully compatible with industrial practices, and have the potential to generate large volumes of hierarchical CNT-g-CF material.
Menzel R, Barg S, Miranda M, et al., 2015, Joule Heating Characteristics of Emulsion-Templated Graphene Aerogels, ADVANCED FUNCTIONAL MATERIALS, Vol: 25, Pages: 28-35, ISSN: 1616-301X
Qian H, Nguyen S, Anthony DB, et al., 2015, Stiff monolithic aerogel matrices for structural fibre composites
© 2015 International Committee on Composite Materials. All rights reserved. Resorcinol-formaldehyde based aerogel precursors were infused into structural carbon fibre weaves, then gelled and carbonised to generate a continuous monolithic matrix network. This hierarchical carbon preform was subsequently infused with polymeric resins, both multifunctional and structural, to produce dense composites. The resulting hierarchical composites have a nanoscale reinforcement in the matrix at up to an order of magnitude higher loadings than typically available by other techniques. Compression, tension, ±45° shear and short beam tests demonstrate the potential of such matrix systems to address matrix dominated failures. However, for the best structural performance it will be necessary to re-optimise the fibre-matrix interface, which is degraded by the current processing regime.
Blaker JJ, Anthony DB, Tang G, et al., 2015, Carbon fibres with modulated properties and shape along the fibre length
© 2015 International Committee on Composite Materials. All rights reserved. The ability to introduce weak regions into carbon fibres at predetermined points should allow failure to occur in a controlled manner, and potentially mitigate the storing of elastic energy leading to sudden catastrophic failure associated with current high performance polymer matrix composites. Here we introduced damage - at the single carbon fibre level - to unsized fibres using a nanosecond pulsed laser source. Various laser treatment parameters were employed to create predefined weak/break points as well as local shape (fibre swelling) modification at the treatment site. The shape and morphology of all individual fibres tested was assessed before and after single fibre tensile tests using SEM to correlate the mechanical properties to fibre shape modification. The laser treatment resulted in swollen fibre regions at the treatment site. In some cases swollen fibres were observed to have a neck region in the centre of the affected region, probably due to simultaneous laser ablation. The tensile mechanical properties of the treated fibres were reduced significantly in comparison to the control fibres; with reductions in strength, strain and modulus of 62%, 55% and 17%, respectively. We demonstrate that the fibre failure occurred in the laser treated region producing two fibre ends with outwardly tapered ends.
Hodge SA, Tay HH, Anthony DB, et al., 2014, Probing the charging mechanisms of carbon nanomaterial polyelectrolytes, FARADAY DISCUSSIONS, Vol: 172, Pages: 311-325, ISSN: 1359-6640
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