Publications
548 results found
Robinson P, Zhang B, Bismarck A, et al., 2016, Interleaving for easy repair of interlaminar damage - Can it be done?
An easy-repair laminate concept is investigated to address the repair problem posed by interlaminar damage due to impact. A carbon epoxy laminate interleaved with PLA is shown to preferentially fail in shear within the interleaf. Good strength recovery is achieved when the laminate is heated and subjected to external pressure.
Jiang Q, Menner A, Bismarck A, 2016, Robust and highly interconnected polyurethane diacrylate based macroporous polymers
Polymerised high internal phase emulsions (polyHIPEs) have drawn extensive interest in recent years; however, industrial applications do require polyHIPEs to be tough and robust. The mechanical properties of polyHIPEs can be tuned by copolymerisation of polyurethane diacrylate (PUDA) and styrene. The resulting open-porous poly(styrene-co-PUDA)HIPEs were much less brittle and friable when compared to conventional poly(styrene-co-divinylbenzene)HIPEs. Moreover, poly(styrene-co-PUDA)HIPEs have impact strengths up to 10 times higher than poly(styrene-co-divinylbenzene)HIPEs. The styrene/PUDA ratio determines the morphology, thermal and mechanical properties of the poly(styrene-co-PUDA) macroporous polymers. The viscous PUDA promotes the formation of small pores in polyHIPEs. A high PUDA content of the copolymer results in low mechanical properties.
Fortea-Verdejo M, Lee KY, Bismarck A, 2016, Bacterial cellulose as reinforcement for natural fibre thermoset composites
It has been previously shown that the introduction of nanocellulose as binder for natural fibre thermoplastic and thermoset composites can enhance the mechanical properties of natural fibre composites. We aim to investigate the effect that bacterial cellulose (BC) has as binder, when introduced in different thermoset-flax fibre composites. Two matrices were investigated, epoxy and phenolic resins. To introduce the bacterial cellulose into the composites, a preform using BC as binder for loose flax fibres was manufactured. The preform was then infused with the thermosetting resins and cured. The resins penetrated the preforms during infusion, however, no significant improvement of the tensile properties could be seen when introducing BC for neither of the resins.
Mautner A, Maples HA, Sehaqui H, et al., 2016, Nitrate removal from water using a nanopaper ion-exchanger, Environmental Science: Water Research & Technology, Vol: 2, Pages: 117-124, ISSN: 2053-1400
Nitrates seriously affect drinking water quality. We herein present a process for the efficient removal of nitrates from water using a nanopaper ion-exchanger, which can be operated in flow-through conditions. The nanopaper ion-exchanger was produced from nanofibrillated cellulose obtained from fibre sludge, a paper-production waste stream, using a simple paper-making process. The cellulose nanofibrils were modified with quaternary trimethylammonium groups. The performance of these cationic nanopaper ion-exchangers was assessed with respect to their permeance and nitrate adsorption. Nitrates could be successfully captured onto the cationic nanopaper and thus rejected from contaminated water during dynamic filtration experiments. The ion-exchange nanopaper had adsorption capacities in the range of commercial available adsorbers but with the advantage of reduced contact time.
Bismarck A, Maples HA, Tridech C, et al., 2016, Controllable stiffness composites: An overview
© 2016, European Conference on Composite Materials, ECCM. All rights reserved.Composites with controllable stiffness have a number of potential applications including their use as skin materials in morphing aerostructures. Much work has focused on the development of such materials, which are required to withstand aerodynamic loads but also deform on demand at relatively low actuation forces. We provide an overview of the work carried out at Imperial College London on the development of high performance controllable stiffness composites. Two composite designs were explored, 1) composites containing thermoplastic interphases and 2) composites containing thermoplastic interleaf layers. Large reductions in stiffness of up to 99% were achieved when the composites were heated above the glass transition temperatures of the polymer interphase or interleaf layer. At these temperatures the composites could be deformed significantly and would retain their shape when cooled to room temperature. The process was completely reversible as the composites would return to their original configuration when reheated without an applied load. Self-deploying structures have also been manufactured from the controllable stiffness materials using the shape memory effect of the composites.
Zhang B, Robinson P, Bismarck A, et al., 2016, Modelling the shape memory capability of an interleaved composite
A composite, consisting of carbon fibre reinforced epoxy laminae and polystyrene interleaf layers, has been developed which exhibits controllable stiffness and a shape memory capability upon heating. This paper investigates finite element modelling of the shape memory capability of this composite. Such modelling could be useful in the design of deployable structures made of this shape memory composite.
Menner A, Jiang Q, Bismarck A, 2016, Spring elements for rewod energy harvesters: Printing emulsion templates to manufacture macroporous polymers
We aim to develop an energy harvesting device that allows charging a battery of e.g. a smart phone while jogging simply by converting mechanical energy into electrical energy using the "REWOD" (Reverse-Electrowetting-On-Dielectric) effect. A vital part of such an energy harvester are highly interconnected and flexible macroporous polymer springs which are required to improve the harvesting efficiency. We use emulsion templates as inks and syringe print them on the harvester's dielectric in any desired shape and dimension (e.g. cages having dimensions ranging from 2mm x2mm down to 0.5mmx0.5mm which are up to 400 μm high). UV-polymerisation of the polyurethane diacrylate/ethylhexyl acrylate based continuous phase of the emulsion templates and subsequent removal of the internal phase yields in highly flexible macroporous polymer springs: cyclic compression tests confirmed that they can repeatedly be compressed by 70% without experiencing permanent plastic deformation. Furthermore, we will present a REWOD energy harvesting prototype achieving a capacity change of up to 1000pF upon mechanical deformation.
De Luca F, Bismarck A, Shaffer MSP, 2016, Anisotropic nanostructure inspired by nature for energy abosrbing composite interfaces
© 2016, European Conference on Composite Materials, ECCM. All rights reserved.The "brick-and-mortar" structure of natural nacre is well known for its combination of high stiffness, strength and toughness thanks to well organised hard inclusions, experiencing pull-out within a soft organic matrix rather than fracture upon loading. Mimicking the structure of nacre while maintaining the same phase proportions and aspect ratio, but at a smaller length scale, opens up the possibility to create composite materials with high performance and large energy absorption properties through interface deformation. Therefore, Layered Double Hydroxide (LDH) nanoplatelets and poly(sodium 4-styrene sulfonate) (PSS) polylelectrolyte were assembled together with a high degree of alignment using Layer-by-Layer (LbL) assembly, resulting in a dense and well organized nanostructure similar to that of nacre. The mechanical properties of the nacre-nanomimetics were comparable to those of natural nacre while the plastic deformation was found amplified. The amplification of the proportion of plastic deformation can be explained by an increase in the volume of platelet interfaces per unit volume at the nanometer length scale. The known toughening mechanisms of nacre, such as platelet sliding and interlocking as well as crack deflection, were also found to occur in the reduced length scale embodiment.
Mautner A, Lee KY, Wan Nawawi WMF, et al., 2016, Cellulose nanopaper composites: Influence of nanopaper characteristics on composite properties
© 2016, European Conference on Composite Materials, ECCM. All rights reserved.Nanocellulose, cellulose in the form of nanofibrils (CNF), has gained considerable attention in recent years as reinforcement agent for the production of composite materials due to its excellent mechanical and chemical properties, with the Young's modulus even outperforming glass fibres. One promising approach to produce nanocomposites based on nanocellulose is to utilize nanopapers as reinforcement in laminated composites, enabling better exploitation of the outstanding mechanical properties of CNF compared to composites in which CNF are introduced in a different way. Accordingly, the characteristics of the nanopapers also influence the properties of the composites. One parameter that is anticipated to influence the final properties of composites a lot is the porosity of the nanopaper employed. A low porosity shows high resistance for the resin to enter into the nanopaper structure hence resulting in lower mechanical properties as potentially possible. Our approach was to alter the porosity of the nanopapers by solvent-exchanging the CNF suspension with different types of organic solvents prior to papermaking to allow for a better infiltration of the resin.
Fortea-Verdejo M, Lee KY, Bismarck A, 2016, Bacterial cellulose as reinforcement for natural fibre thermoset composites
© 2016, European Conference on Composite Materials, ECCM. All rights reserved.It has been previously shown that the introduction of nanocellulose as binder for natural fibre thermoplastic and thermoset composites can enhance the mechanical properties of natural fibre composites. We aim to investigate the effect that bacterial cellulose (BC) has as binder, when introduced in different thermoset-flax fibre composites. Two matrices were investigated, epoxy and phenolic resins. To introduce the bacterial cellulose into the composites, a preform using BC as binder for loose flax fibres was manufactured. The preform was then infused with the thermosetting resins and cured. The resins penetrated the preforms during infusion, however, no significant improvement of the tensile properties could be seen when introducing BC for neither of the resins.
Barbara I, Birot M, Bismarck A, et al., 2016, Preparation of divinyl esters by transvinylation between vinyl acetate and dicarboxylic acids, ARKIVOC, Vol: 2016, Pages: 23-35, ISSN: 1551-7004
Transvinylation of aromatic and aliphatic diacids with vinyl acetate using several catalyticsystems have been studied under conventional heating and microwave activation. In any case, asingle addition of catalyst gave only low conversion into diester, due to a rapid deactivation ofthe catalysts, the best results being obtained with [pyridine]2·Pd(OAc)2. Successive additions ofPd(OAc)2 as catalyst gave better results with a 65% yield in isolated pure divinyl dodecanedioateafter the successive addition of three catalyst portions. Kinetics and catalytic mechanismconsiderations helped to discuss these results.
Lee K-Y, Bismarck A, 2016, Bacterial NanoCellulose as Reinforcement for Polymer Matrices, BACTERIAL NANOCELLULOSE: FROM BIOTECHNOLOGY TO BIO-ECONOMY, Editors: Gama, Dourado, Bielecki, Publisher: ELSEVIER SCIENCE BV, Pages: 109-122, ISBN: 978-0-444-63458-0
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- Citations: 9
De Luca F, Menzel R, Blaker JJ, et al., 2015, Nacre-nanomimetics: Strong, Stiff, and Plastic, ACS APPLIED MATERIALS & INTERFACES, Vol: 7, Pages: 26783-26791, ISSN: 1944-8244
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- Citations: 26
Tebboth M, Kogelbauer A, Bismarck A, 2015, Highly permeable macroporous polymers via controlled agitation of emulsion templates, CHEMICAL ENGINEERING SCIENCE, Vol: 137, Pages: 786-795, ISSN: 0009-2509
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- Citations: 22
Fortea-Verdejo M, Lee K-Y, Zimmermann T, et al., 2015, Upgrading flax nonwovens: nanocellulose as binder to produce rigid and robust flax fibre preforms, Composites Part A - Applied Science and Manufacturing, Vol: 83, Pages: 63-71, ISSN: 1359-835X
Typically in flax fibre nonwovens, the fibrous web is mechanically bonded (via entanglement and interlocking of fibres) or thermally bonded (by melting of polymer fibres). Recently, we showed that bacterial cellulose (BC) can be used as effective binder to produce rigid and robust natural fibre nonwovens without the need for polymer binders. Here, we further expand this work to manufacture flax nonwovens by utilising various types of (nano)cellulose, including nanofibrillated cellulose (NFC), BC and pulp fibres. Two preform manufacturing processes are investigated, namely single-step filtration and layer-by-layer filtration. Both BC and NFC serve as excellent binders for loose flax fibres due to their high surface area whilst pulp fibres are a poor binder for flax fibres. This is attributed to the low surface area of pulp compared to BC and NFC, which leads to a lower contact area between flax fibres and pulp. Furthermore, the larger fibre diameter of pulp results in a poorer packing efficiency and, therefore, a higher porosity of 67% compared to preforms made with BC or NFC as binder, which have a porosity of ∼60%. The manufactured preforms possess excellent tensile (View the MathML source, View the MathML source) and flexural (σ = 21.1 MPa, E = 2.2 GPa) properties. Layer-by-layer filtration process results in flax nonwovens, which exhibit even better tensile and flexural properties. This is hypothesised to be due to the better distribution of the fibrous nanocellulose network throughout the preform.
Simpson RL, Nazhat SN, Blaker JJ, et al., 2015, A comparative study of the effects of different bioactive fillers in PLGA matrix composites and their suitability as bone substitute materials: a thermo-mechanical and in vitro investigation, Journal of The Mechanical Behavior of Biomedical Materials, Vol: 50, Pages: 277-289, ISSN: 1751-6161
Bone substitute composite materials with poly(L-lactide-co-glycolide) (PLGA) matrices and four different bioactive fillers: CaCO3, hydroxyapatite (HA), 45S5 Bioglass(®) (45S5 BG), and ICIE4 bioactive glass (a lower sodium glass than 45S5 BG) were produced via melt blending, extrusion and moulding. The viscoelastic, mechanical and thermal properties, and the molecular weight of the matrix were measured. Thermogravimetric analysis evaluated the effect of filler composition on the thermal degradation of the matrix. Bioactive glasses caused premature degradation of the matrix during processing, whereas CaCO3 or HA did not. All composites, except those with 45S5 BG, had similar mechanical strength and were stiffer than PLGA alone in compression, whilst all had a lower tensile strength. Dynamic mechanical analysis demonstrated an increased storage modulus (E') in the composites (other than the 45S5 BG filled PLGA). The effect of water uptake and early degradation was investigated by short-term in vitro aging in simulated body fluid, which indicated enhanced water uptake over the neat polymer; bioactive glass had the greatest water uptake, causing matrix plasticization. These results enable a direct comparison between bioactive filler type in poly(α-hydroxyester) composites, and have implications when selecting a composite material for eventual application in bone substitution.
Tebboth M, Jiang Q, Kogelbauer A, et al., 2015, Inflatable Elastomeric Macroporous Polymers Synthesized from Medium Internal Phase Emulsion Templates, ACS APPLIED MATERIALS & INTERFACES, Vol: 7, Pages: 19243-19250, ISSN: 1944-8244
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- Citations: 43
Javaid A, Ho KKC, Bismarck A, et al., 2015, Carbon fibre-reinforced poly(ethylene glycol) diglycidylether based multifunctional structural supercapacitor composites for electrical energy storage applications, Journal of Composite Materials, Vol: 50, Pages: 2155-2163, ISSN: 1530-793X
Zubairi SI, Mantalaris A, Bismarck A, 2015, Pore Interconnectivity Analysis of Porous Three Dimensional Scaffolds of Poly (3-Hydroxybutyric Acid) (PHB) and Poly(3-Hydroxybutyric-co-3-Hydroxyvaleric Acid) (PHBV) Through Non-Invasive Color Staining Method, SAINS MALAYSIANA, Vol: 44, Pages: 1351-1356, ISSN: 0126-6039
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- Citations: 2
Ferrer J, Menner A, Bismarck A, 2015, Micro vs. macrofluidics. Encapsulation of hydrochloric acid in porous polymer beads, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Paschinger W, Bismarck A, 2015, Porous polymers in situ filled with RT-IL and their possible application as separator membranes in Li-ion batteries, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Menner A, Jiang Q, Bismarck A, 2015, Flexible macroporous polymer cages as spacer/spring elements for REWOD energy harvesting devices, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Jiang Q, Menner A, Bismarck A, 2015, Printed macroporous polymers with complex structures and shapes, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Tebboth M, Kogelbauer A, Bismarck A, 2015, Liquid-Liquid Extraction within Emulsion Templated Macroporous Polymers, INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, Vol: 54, Pages: 7284-7291, ISSN: 0888-5885
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- Citations: 18
Qian H, Nguyen S, Anthony DB, et al., 2015, Stiff monolithic aerogel matrices for structural fibre composites, 20th International Conference on Composite Materials, Publisher: iccm-central.org
Resorcinol-formaldehyde based aerogel precursors were infused into structural carbon fibreweaves, then gelled and carbonised to generate a continuous monolithic matrix network. Thishierarchical carbon preform was subsequently infused with polymeric resins, both multifunctional andstructural, to produce dense composites. The resulting hierarchical composites have a nanoscalereinforcement in the matrix at up to an order of magnitude higher loadings than typically available byother techniques. Compression, tension, ±45° shear and short beam tests demonstrate the potential ofsuch matrix systems to address matrix dominated failures. However, for the best structuralperformance it will be necessary to re-optimise the fibre-matrix interface, which is degraded by thecurrent processing regime.
Blaker JJ, Anthony DB, Tang G, et al., 2015, Carbon fibres with modulated properties and shape along the fibre length, 20th International Conference on Composite Materials, Publisher: ICCM
This paper presents a detailed experimental examination of the influence of the thickness of flatenergy directors (ED) on the ultrasonic welding (USW) process for carbon fibre/polyetherimidecomposites. Three thicknesses of flat ED were compared: 0.06 mm, 0.25 mm and 0.50 mm. Power anddisplacement data for 0.06 mm-thick EDs did not clearly show the stages of the process and thelocation of the optimum for best weld quality. Consequently, an investigation of samples welded atdifferent stages in the welding process had to be performed. For 0.06 mm-thick EDs, the optimum wasdetermined to occur at the beginning of the downward displacement of the sonotrode in the vibrationphase. The output parameters at the optimum conditions for all thicknesses were compared. Averagelap shear strength was found to be lowest for 0.06 mm-thick EDs. Based on the analysis of the fracturesurfaces, resin flakes and voids were observed when using the thinnest energy directors, indicatingthermal degradation. These observations suggest that thin energy directors are not as efficient asthicker EDs (i.e. 0.25 mm) to achieve preferential heat generation at the weld line, leading to lessconsistent weld quality.
Zubairi SI, Bismarck A, Mantalaris A, 2015, THE EFFECT OF SURFACE HETEROGENEITY ON WETTABILITY OF POROUS THREE DIMENSIONAL (3-D) SCAFFOLDS OF POLY(3-HYDROXYBUTYRIC ACID) (PHB) AND POLY(3-HYDROXYBUTYRIC-CO-3-HYDROXYVALERIC ACID) (PHBV), JURNAL TEKNOLOGI, Vol: 75, Pages: 305-312, ISSN: 0127-9696
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- Citations: 10
Tebboth M, Kogelbauer A, Bismarck A, 2015, Effectiveness of Emulsion-Templated Macroporous Polymer Micromixers Characterized by the Bourne Reaction, INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, Vol: 54, Pages: 5974-5981, ISSN: 0888-5885
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- Citations: 16
Bismarck A, 2015, Editorial corner - a personal view Added function - Added value: Multifunctional high-performance composites, EXPRESS POLYMER LETTERS, Vol: 9, Pages: 489-489, ISSN: 1788-618X
Kwak M, Robinson P, Bismarck A, et al., 2015, Microwave curing of carbon-epoxy composites: Penetration depth and material characterisation, Composites Part A - Applied Science and Manufacturing, Vol: 75, Pages: 18-27, ISSN: 1359-835X
Microwave heating has several major advantages over conventional conductive heating when used to cure carbon–epoxy composites, especially in speed of processing. Despite this and many other well-known advantages, microwave heating of carbon–epoxy composites has not taken off in industry, or even academia, due to the problems associated with microwave energy distribution, arcing, tool design and (ultimately) part quality and consistency, thus leading to a large scepticism regarding the technique/technology for heating such type of materials. This paper presents some evidence which suggests that with the correct hardware and operating procedure/methodology, consistent and high quality carbon–epoxy laminates can be produced, with the possibility of scaling up the process, as demonstrated by the micro- and macro-scale mechanical test results. Additionally, the author proposes a methodology to practically measure the maximum microwave penetration depth of a carbon–epoxy composite material.
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