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Journal articleMohammed A, Bissoon R, Bajnath E, et al., 2018,
Multistage extraction and purification of waste Sargassum natans to produce sodium alginate: an optimization approach
, Carbohydrate Polymers, Vol: 198, Pages: 109-118, ISSN: 0144-8617Sargassum in the Caribbean region has affected the livelihood of several coastal communities due to the influx of large quantities of the seaweed in recent times. This article seeks to explore how waste Sargassum natans can be utilized to produce sodium alginate. The novelty in this research lies in the optimization process, whereby multistage extraction and precipitation were investigated over commonly used single stage processing, in an effort to maximize both yield and purity. The results showed that a maximum yield of 19% was observed after 1 stage, while the purity was 74% after 4 stages. In addition, optimization of the multistage precipitation process using the Global Optimization Toolbox in MATLAB R2017b provided a novel model which indicated that a compromise between the maximum purity and yield can be obtained at 3 stages; 71–74% and 12–16% respectively. Furthermore, characterization was done using FTIR and NMR, with results comparable to a commercial sodium alginate brand, giving absorption bands at 1610 cm−1and 1395 cm-1and an M/G ratio of 0.51 respectively.
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Journal articleNarducci F, Lee K, Pinho ST, 2018,
Realising damage-tolerant nacre-inspired CFRP
, Journal of the Mechanics and Physics of Solids, Vol: 116, Pages: 391-402, ISSN: 0022-5096Inthiswork,anacre-inspiredCarbonFibreReinforcedPolymer(CFRP)compositeis designed,synthesisedandtested. Analyticalandnumericalmodelsareusedtodesign a tiled micro-structure, mimicking the staggered arrangement of ceramic platelets in nacreandexploitinggeometricalinterlocksforcrackdeflectionanddamagediffusion. The designed pattern of tiles is then laser-engraved in the laminate plies. In order to increase the damage-spreading capability of the material, a thin layer of poly(lactic acid) (PLA) is film-cast on the interlaminar region, both as a continuous film and as a pattern of fractal-shaped patches. Three-point bending tests show how the nacre-like micro-structure succeeds in deflecting cracks, with damage diffusion being significantly improved by the addition of PLA at the interface between tiles. It is observed that a texture of discontinuous fractal-shaped PLA patches can increase damage diffusion, by promoting the unlocking of tiles whilst preserving the interface strength.
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Journal articleHervy M, Blaker JJ, Braz AL, et al., 2018,
Mechanical response of multi-layer bacterial cellulose nanopaper reinforced polylactide laminated composites
, Composites Part A: Applied Science and Manufacturing, Vol: 107, Pages: 155-163, ISSN: 1359-835XIn this study, we investigated the mechanical response of polylactide (PLLA) reinforced with multiple layers of BC nanopaper. Laminated composites consisting of 1, 3, 6 and 12 sheet(s) of BC nanopaper were produced. It was observed that increasing the number of BC nanopaper led to an increase in the porosity of the resulting BC nanopaper-reinforced PLLA laminated composites. The tensile moduli of the laminated composites were found to be ∼12.5 – 13.5 GPa, insensitive to the number of sheets of BC nanopaper in the composites. However, the tensile strength of the laminated composites decreased by 21% (from 121 MPa to 95 MPa) when the number of reinforcing BC nanopaper sheets increased from 1 to 12 sheets. This was attributed to the presence and severity of the scale-induced defects increased with increasing BC nanopaper sheets in the PLLA laminated composites.
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Journal articleNarducci F, Lee KY, Pinho ST, 2018,
Interface micro-texturing for interlaminar toughness tailoring: a film-casting technique
, Composites Science and Technology, Vol: 156, Pages: 203-214, ISSN: 0266-3538In this work, we developed a film-casting technique to deposit thin (13 μm) layers of poly(lactic acid) (PLA) on the interface of carbon/epoxy prepregs, with the aim of increasing the interlaminar toughness. PLA patches with fractal shape were explored, based on preliminary results showing that the toughening effect increases when PLA is deposited at multiple scales simultaneously. Double Cantilever Beam (DCB) and 4-point End-Notched Flexure (4ENF) tests showed an increase in interlaminar toughness of, respectively, up to 80% for Mode I and 12% for Mode II. This is specially remarkable because the interface thickness is only 13 μm. Moreover, it was demonstrated that this technique can promote interaction between neighbouring layers where PLA has been cast, thus triggering fibre bridging and leading to a further enhancement of toughness.
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BookLee K-Y, 2018,
Nanocellulose and Sustainability: Production, Properties, Applications, and Case Studies
, Publisher: CRC Press/Taylor Francis, ISBN: 9781498761031 -
Book chapterSantmarti A, Lee K, 2018,
Crystallinity and Thermal Stability of Nanocellulose
, Nanocellulose and Sustainability Production, Properties, Applications, and Case Studies, Editors: Lee, Publisher: Taylor and Francis / CRC Press, Pages: 67-86, ISBN: 9781498761031 -
Journal articleMautner A, Mayer F, Hervy M, et al., 2017,
Better together: synergy in nanocellulose blends
, Philosophical Transactions of the Royal Society A. Mathematical, Physical and Engineering Sciences, Vol: 376, ISSN: 1364-503XCellulose nanopapers have gained significantattention in recent years as large-scale reinforcementfor high-loading cellulose nanocomposites, substratesfor printed electronics and filter nanopapers forwater treatment. The mechanical properties ofnanopapers are of fundamental importance forall these applications. Cellulose nanopapers cansimply be prepared by filtering a suspension ofnanocellulose, followed by heat consolidation. It wasalready demonstrated that the mechanical propertiesof cellulose nanopapers can be tailored by the finenessof the fibrils used or by modifying nanocellulosefibrils for instance by polymer adsorption, butnanocellulose blends remain underexplored. In thiswork, we show that the mechanical and physicalproperties of cellulose nanopapers can be tuned bycreating nanopapers from blends of various gradesof nanocellulose, i.e. (mechanically refined) bacterialcellulose or cellulose nanofibrils extracted fromnever-dried bleached softwood pulp by chemical andmechanical pre-treatments. We found that nanopapersmade from blends of two or three nanocellulosegrades show synergistic effects resulting in improvedstiffness, strength, ductility, toughness and physicalproperties.This article is part of a discussion meeting issue‘New horizons for cellulose nanotechnology’.
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Journal articleKontturi KS, Biegaj K, Mautner A, et al., 2017,
Noncovalent Surface Modification of Cellulose Nanopapers by Adsorption of Polymers from Aprotic Solvents
, LANGMUIR, Vol: 33, Pages: 5707-5712, ISSN: 0743-7463Basic adsorption of hydrophobic polymers from aprotic solvents was introduced as a platform technology to modify exclusively the surfaces of cellulose nanopapers. Dynamic vapor sorption demonstrated that the water vapor uptake ability of the nanopapers remained unperturbed, despite strong repellency to liquid water caused by the adsorbed hydrophobic polymer on the surface. This was enabled by the fact that the aprotic solvents used for adsorption did not swell the nanopaper unlike water that is generally applied as the adsorption medium in such systems. As case examples, the adsorptions of polystyrene (PS) and poly(trifluoroethylene) (PF3E) were followed by X-ray photoelectron spectroscopy and water contact angle measurements, backed up with morphological analysis by atomic force microscopy. The resulting nanopapers are useful in applications like moisture buffers where repellence to liquid water and ability for moisture sorption are desired qualities.
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Book chapterLee K, Daud NJ, 2017,
Surface Modification of Nanocellulose
, Handbook of Nanocellulose and Cellulose Nanocomposites, 2 Volume Set, Editors: Kargarzadeh, Ahmad, Thomas, Dufresne, Publisher: John Wiley & Sons, Pages: 101-122, ISBN: 9783527338665With its coverage of a wide variety of materials, important characterization tools and resulting applications, this is an essential reference for beginners as well as experienced researchers.
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Journal articleHervy M, Santmarti A, Lahtinen P, et al., 2017,
Sample geometry dependency on the measured tensile properties of cellulose nanopapers
, Materials & Design, Vol: 121, Pages: 421-429, ISSN: 0261-3069Miniaturised test specimens are often used for the tensile testing of cellulose nanopapers as there are currently no standardised test geometries to evaluate their tensile properties. In this work, we report the influence of test specimen geometries on the measured tensile properties of plant-derived cellulose nanofibres (CNF) and microbially synthesised bacterial cellulose (BC) nanopapers. Four test specimen geometries were studied: (i) miniaturised dog bone specimen with 2 mm width, (ii) miniaturised rectangular specimen with 5 mm width, (iii) standard dog bone specimen with 5 mm width and (iv) standard rectangular specimen with 15 mm width. It was found that the tensile moduli of both CNF and BC nanopapers were not significantly influenced by the test specimen geometries if an independent strain measurement system (video extensometer) was employed. The average tensile strength of the cellulose nanopapers is also influenced by test specimen geometries. It was observed that the smaller the test specimen width, the higher the average tensile strength of the cellulose nanopapers. This can be described by the weakest link theory, whereby the probability of defects present in the cellulose nanopapers increases with increasing test specimen width. The Poisson's ratio and fracture resistance of CNF and BC nanopapers are also discussed.
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Journal articleSong W, Barber K, Lee KY, 2017,
Heat-induced bubble expansion as a route to increase the porosity of foam-templated bio-based macroporous polymers
, Polymer, Vol: 118, Pages: 97-106, ISSN: 0032-3861Macroporous polymers were prepared by mechanically frothing a bio-based epoxy resin and hardener mixture to first create air-in-resin liquid foams, followed by curing of these liquid foams. It was found that heating the air-in-resin liquid foams prior to their gelation decreased the viscosity of the resin mixture and increased the pressure of the air bubbles, leading to an isotropic expansion of the air bubbles. This resulted in an increase in the porosity of the resulting foam-templated macroporous polymers from 71% to 85%. Correspondingly, the compressive moduli (E) and strengths (σ) of the foam-templated macroporous polymers decreased from 231 MPa and 5.9 MPa, respectively, to 58 MPa and 1.9 MPa, respectively. This decrease is attributed to an increase in the porosity and pore throat frequency of the foam-templated macroporous polymers when heat was applied to the liquid foams. The deformation of the pores based on in situ SEM micro-compression test of the fabricated foam-templated macroporous polymers is also discussed.
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Journal articleTagarielli V, song Y, li Y, et al., 2017,
Measurements of the mechanical response of unidirectional 3D-printed PLA
, Materials & Design, Vol: 123, Pages: 154-164, ISSN: 0261-3069Fully dense PLA blocks were manufactured by 3D-printing, depositing a polymer filament in a single direction via the fusion deposition method (FDM). Specimens were cut from printed blocks using conventional machining and were used to perform tension, compression and fracture experiments along different material directions. The elasto-plastic material response was found to be orthotropic and characterised by a strong tension-compression asymmetry; the material was tougher when loaded in the extrusion direction than in the transverse direction. The response of the unidirectional, 3D-printed material was compared to that of homogeneous injection-moulded PLA, showing that manufacturing by 3D-printing improves toughness; the effects of an annealing thermal cycle on the molecular structure and the mechanical response of the material were assessed.
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Journal articleFortea-Verdejo M, Bumbaris E, Burgstaller C, et al., 2017,
Plant fibre reinforced polymers: where do we stand in terms of tensile properties?
, International Materials Reviews, Vol: 62, Pages: 441-464, ISSN: 1743-2804Plant fibres have a unique set of properties ranging from being stiff and brittle, such as hemp and flax, to more ductile, such as coir, combining these properties with their cost and availability makes them attractive alternative reinforcements for the production of greener composites. This article reviews the tensileproperties ofvarious plant fibreor plant based natural fibre-reinforced polymersreported in the literature. We critically discuss the use of plant fibres as reinforcement for the production of bio-based,renewable or green polymer composites, showing the evolution of the properties of plant fibre composites. The reported tensile properties of plant fibre-reinforced polymer composites arecompared against various renewable and non-renewableengineering/commoditypolymers as well as the tensile propertiesof commercially available randomly oriented glass fibre-reinforced polymers (GFRP). Green composites containing random short plant fibres dohave similar properties to randomly oriented GFRP at a lower overall part weight. Unidirectional plant fibre-reinforced polymers offer better performance than randomly oriented GFRP and could have the potential to be adapted in applications requiring even higher mechanical performance, especially in areas where the useof costly synthetic fibres might be less attractive. Furthermore, plant fibres can also be regarded as effective fillers to replace more expensive polymersand improve the green credentialsof final composite parts. These features may motivate the industry to introduce more plant fibre-based products to the market.
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Journal articleShamsuddin SR, Lee KY, Bismarck A, 2016,
Ductile unidirectional continuous rayon fibre-reinforced hierarchical composites
, Composites Part A: Applied Science and Manufacturing, Vol: 90, Pages: 633-641, ISSN: 1359-835XEndless rayon fibres (Cordenka®) were used to reinforce polyhydroxybutyrate (PHB) nanocomposites containing 2.5 wt.% nanofibrillated cellulose (NFC) to create truly green hierarchical composites. Unidirectional (UD) composites with 50–55% fibre volume fraction were produced using a solvent-free continuous wet powder impregnation method. The composites exhibit ductile failure behaviour with a strain-to-failure of more than 10% albeit using a very brittle matrix. Improvements at a model composite level were translated into higher mechanical properties of UD hierarchical composites. The Young’s moduli of rayon fibre-reinforced (NFC-reinforced) PHB composites were about 15 GPa. The tensile and flexural strength of hierarchical PHB composites increased by 15% and 33% as compared to the rayon fibre-reinforced neat PHB composites. This suggests that incorporation of NFC into the PHB matrix binds the rayon fibres, which does affect the load transfer between the constituents resulting in composites with better mechanical properties.
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Journal articleFerguson A, Khan U, Walsh M, et al., 2016,
Understanding the dispersion and assembly of bacterial cellulose in organic solvents
, Biomacromolecules, Vol: 17, Pages: 1845-1853, ISSN: 1526-4602The constituent nanofibrils of bacterial cellulose are of interest to many researchers because of their purity and excellent mechanical properties. Mechanisms to disrupt the network structure of bacterial cellulose (BC) to isolate bacterial cellulose nanofibrils (BCN) are limited. This work focuses on liquid-phase dispersions of BCN in a range of organic solvents. It builds on work to disperse similarly intractable nanomaterials, such as single-walled carbon nanotubes, where optimum dispersion is seen for solvents whose surface energies are close to the surface energy of the nanomaterial; bacterial cellulose is shown to disperse in a similar fashion. Inverse gas chromatography was used to determine the surface energy of bacterial cellulose, under relevant conditions, by quantifying the surface heterogeneity of the material as a function of coverage. Films of pure BCN were prepared from dispersions in a range of solvents; the extent of BCN exfoliation is shown to have a strong effect on the mechanical properties of BC films and to fit models based on the volumetric density of nanofibril junctions. Such control offers new routes to producing robust cellulose films of bacterial cellulose nanofibrils.
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Journal articleLee K, bismarck A, 2016,
Single step functionalization of celluloses with differing degrees of reactivity as a route for in situ production of all-cellulose nanocomposites
, Nanocomposites, Vol: 1, Pages: 214-222, ISSN: 2055-0332A method of manufacturing all-cellulose nanocomposites using a single-step functionalization of two different celluloses with differing reactivities is presented. All-cellulose nanocomposites are produced by esterification of microcrystalline cellulose (MCC) in pyridine with hexanoic acid in the presence of bacterial cellulose (BC) followed by solvent removal. Neat MCC is more susceptible to esterification, with an accessible amount of hydroxyl groups of 1.79 compared to BC, with an accessible hydroxyl group content of 0.80. As a result, neat MCC undergoes severe bulk modification, turning into a toluene-soluble cellulose hexanoate (C6-MCC) while BC undergoes surface-only modification. Solution casted C6-MCC films have a tensile modulus and strength of 0.99 GPa and 23.1 MPa, respectively. The presence of 5 wt.% BC in C6-MCC leads to an increase in tensile modulus and strength of the resulting nanocomposites to 1.42 GPa and 28.4 MPa, respectively.
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Book chapterLee 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- Author Web Link
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- Citations: 9
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Journal articleFortea-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: 1359-835XTypically 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.
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Journal articleHervy M, Evangelisti S, Lettieri P, et al., 2015,
Life cycle assessment of nanocellulose-reinforced advanced fibre composites
, Composites Science and Technology, Vol: 118, Pages: 154-162, ISSN: 0266-3538The research and development of nanocellulose-reinforced polymer composites have dramatically increased in the recent years due to the possibility of exploiting the high tensile stiffness and strength of nanocellulose. In the work, the environmental impacts of bacterial cellulose (BC)- and nanofibrillated cellulose (NFC)-reinforced epoxy composites were evaluated using life cycle assessment (LCA). Neat polylactide (PLA) and 30% randomly oriented glass fibre-reinforced polypropylene (GF/PP) composites were used as benchmark materials for comparison. Our cradle-to-gate LCA showed that BC- and NFC-reinforced epoxy composites have higher global warming potential (GWP) and abiotic depletion potential of fossil fuels (ADf) compared to neat PLA and GF/PP even though the specific tensile moduli of the nanocellulose-reinforced epoxy composites were higher than neat PLA and GF/PP. However, when the use phase and the end-of-life of nanocellulose-reinforced epoxy composites were considered, the “green credentials” of nanocellulose-reinforced epoxy composites were comparable to that of neat PLA and GF/PP composites. Our life cycle scenario analysis showed that the cradle-to-grave GWP and ADf of BC- and NFC-reinforced epoxy composites could be lower than neat PLA when the composites contains more than 60 vol.-% nanocellulose. Our LCA model suggests that nanocellulose-reinforced epoxy composites with high nanocellulose loading is desired to produce materials with “greener credentials” than the best performing commercially available bio-derived polymer.
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Journal articleLee K, Quero F, Coveney A, et al., 2015,
Stress Transfer Quantification in Gelatin-Matrix Natural Composites with Tunable Optical Properties
, Biomacromolecules, Vol: 16, Pages: 1784-1793, ISSN: 1526-4602This work reports on the preparation and characterization of natural composite materials prepared from bacterial cellulose (BC) incorporated into a gelatin matrix. Composite morphology was studied using scanning electron microscopy and 2D Raman imaging revealing an inhomogeneous dispersion of BC within the gelatin matrix. The composite materials showed controllable degrees of transparency to visible light and opacity to UV light depending on BC weight fraction. By adding a 10 wt % fraction of BC in gelatin, visible (λ = 550 nm) and UV (λ = 350 nm) transmittances were found to decrease by ∼35 and 40%, respectively. Additionally, stress transfer occurring between the gelatin and BC fibrils was quantified using Raman spectroscopy. This is the first report for a gelatin–matrix composite containing cellulose. As a function of strain, two distinct domains, both showing linear relationships, were observed for which an average initial shift rate with respect to strain of −0.63 ± 0.2 cm–1%–1 was observed, followed by an average shift rate of −0.25 ± 0.03 cm–1%–1. The average initial Raman band shift rate value corresponds to an average effective Young’s modulus of 39 ± 13 GPa and 73 ± 25 GPa, respectively, for either a 2D and 3D network of BC fibrils embedded in the gelatin matrix. As a function of stress, a linear relationship was observed with a Raman band shift rate of −27 ± 3 cm–1GPa–1. The potential use of these composite materials as a UV blocking food coating is discussed.
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Journal articleMautner A, Lee K-Y, Tammelin T, et al., 2015,
Cellulose nanopapers as tight aqueous ultra-filtration membranes
, REACTIVE & FUNCTIONAL POLYMERS, Vol: 86, Pages: 209-214, ISSN: 1381-5148- Author Web Link
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- Citations: 121
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Journal articleLee K-Y, Aitomaki Y, Berglund LA, et al., 2014,
On the use of nanocellulose as reinforcement in polymer matrix composites
, COMPOSITES SCIENCE AND TECHNOLOGY, Vol: 105, Pages: 15-27, ISSN: 0266-3538- Author Web Link
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- Citations: 536
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Journal articleLee K-Y, Blaker JJ, Heng JYY, et al., 2014,
pH-triggered phase inversion and separation of hydrophobised bacterial cellulose stabilised Pickering emulsions
, REACTIVE & FUNCTIONAL POLYMERS, Vol: 85, Pages: 208-213, ISSN: 1381-5148- Author Web Link
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- Citations: 18
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Journal articleMontrikittiphant T, Tang M, Lee K-Y, et al., 2014,
Bacterial Cellulose Nanopaper as Reinforcement for Polylactide Composites: Renewable Thermoplastic NanoPaPreg
, MACROMOLECULAR RAPID COMMUNICATIONS, Vol: 35, Pages: 1640-1645, ISSN: 1022-1336- Author Web Link
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- Citations: 25
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Journal articleBlaker JJ, Lee K-Y, Walters M, et al., 2014,
Aligned unidirectional PLA/bacterial cellulose nanocomposite fibre reinforced PDLLA composites
, Reactive & Functional Polymers, Vol: 85, Pages: 185-192, ISSN: 1381-5148In an effort to enhance the properties of polylactide (PLA), we have developed melt-spinning techniques to produce both PLA/nanocellulose composite fibres, and a method akin to layered filament winding followed by compression moulding to produce self-reinforced PLA/nanocellulose composites. Poly(L-lactide) (PLLA) fibres were filled with 2 wt.% neat and modified bacterial cellulose (BC) in an effort to improve the tensile properties over neat PLA fibres. BC increased the viscosity of the polymer melt and reduced the draw-ratio of the fibres, resulting in increased fibre diameters. Nonetheless, strain induced chain orientation due to melt spinning led to PLLA fibres with enhanced tensile modulus (6 GPa) and strength (127 MPa), over monolithic PLLA, previously measured at 1.3 GPa and 61 MPa, respectively. The presence of BC also enhanced the nucleation and growth of crystals in PLA. We further produced PLA fibres with 7 wt.% cellulose nanocrystals (CNCs), which is higher than the percolation threshold (equivalent to 6 vol.%). These fibres were spun in multiple, alternating controlled layers onto spools, and subsequently compression moulded to produce unidirectional self-reinforced PLA composites consisting of 60 vol.% PLLA fibres reinforced with 7 wt.% CNC in a matrix of amorphous PDLLA, which itself contained 7 wt.% of CNC. We observed improvements in viscoelastic properties of up to 175% in terms of storage moduli in bending. Furthermore, strains to failure for PLLA fibre reinforced PDLLA were recorded at 17%.
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Journal articleYata T, Lee K-Y, Dharakul T, et al., 2014,
Hybrid Nanomaterial Complexes for Advanced Phage-guided Gene Delivery
, MOLECULAR THERAPY-NUCLEIC ACIDS, Vol: 3, ISSN: 2162-2531- Author Web Link
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- Citations: 30
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Book chapterLee K-Y, Bismarck A, 2014,
Advanced bacterial cellulose composites
, Handbook of Green Materials: Processing Technologies, Properties and Applications (in 4 Volumes), Editors: Oksman, Mathew, Bismarck, ISBN: 9789814566452 -
Book chapterLee K-Y, Bismarck A, 2014,
Chemical surface modification and adhesion of nanocellulose
, Handbook of Green Materials: Processing Technologies, Properties and Applications (in 4 Volumes), Editors: Oksman, Mathew, Bismarck, ISBN: 9789814566452 -
Book chapterLee K-Y, Bismarck A, 2014,
Handbook of Green Materials (volume 3): Processing Technologies, Properties and Applications
, Handbook of Green Materials: Processing Technologies, Properties and Applications (in 4 Volumes), Editors: Oksman, Mathew, Bismarck, Publisher: ICE Publishing, ISBN: 9789814566452 -
Journal articleLee K-Y, Shamsuddin SR, Fortea-Verdejo M, et al., 2014,
Manufacturing Of Robust Natural Fiber Preforms Utilizing Bacterial Cellulose as Binder
, JOVE-JOURNAL OF VISUALIZED EXPERIMENTS, ISSN: 1940-087X- Author Web Link
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- Citations: 21
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Journal articleMautner A, Lee K-Y, Lahtinen P, et al., 2014,
Nanopapers for organic solvent nanofiltration
, Chemical Communications, Vol: 50, Pages: 5778-5781, ISSN: 1364-548XWould it not be nice to have an organic solvent nanofiltration membrane made from renewable resources that can be manufactured as simply as producing paper? Here the production of nanofiltration membranes made from nanocellulose by applying a papermaking process is demonstrated. Manufacture of the nanopapers was enabled by inducing flocculation of nanofibrils upon addition of trivalent ions.
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Book chapterLee K-Y, Bismarck A, 2014,
Creating hierarchical structures in (ligno)cellulosic fibres for green composites
, Natural Fibre Composites, Editors: Hodzic, Shanks, Publisher: Woodhead Publishing, ISBN: 9780857099228 -
Journal articleLee K-Y, Blaker JJ, Murakami R, et al., 2014,
Phase Behavior of Medium and High Internal Phase Water-in-Oil Emulsions Stabilized Solely by Hydrophobized Bacterial Cellulose Nanofibrils
, LANGMUIR, Vol: 30, Pages: 452-460, ISSN: 0743-7463- Author Web Link
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- Citations: 91
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Journal articleLee K-Y, Buldum G, Mantalaris A, et al., 2014,
More Than Meets the Eye in Bacterial Cellulose: Biosynthesis, Bioprocessing, and Applications in Advanced Fiber Composites
, Macromolecular Bioscience, Vol: 14, Pages: 10-32, ISSN: 1616-5195Bacterial cellulose (BC) nanofibers are one of the stiffest organic materials produced by nature. It consists of pure cellulose without the impurities that are commonly found in plant-based cellulose. This review discusses the metabolic pathways of cellulose-producing bacteria and the genetic pathways of Acetobacter xylinum. The fermentative production of BC and the bioprocess parameters for the cultivation of bacteria are also discussed. The influence of the composition of the culture medium, pH, temperature, and oxygen content on the morphology and yield of BC are reviewed. In addition, the progress made to date on the genetic modification of bacteria to increase the yield of BC and the large-scale production of BC using various bioreactors, namely static and agitated cultures, stirred tank, airlift, aerosol, rotary, and membrane reactors, is reviewed. The challenges in commercial scale production of BC are thoroughly discussed and the efficiency of various bioreactors is compared. In terms of the application of BC, particular emphasis is placed on the utilization of BC in advanced fiber composites to manufacture the next generation truly green, sustainable and renewable hierarchical composites.
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Journal articleLau THM, Wong LLC, Lee K-Y, et al., 2013,
Tailored for simplicity: creating high porosity, high performance bio-based macroporous polymers from foam templates
, Green Chemistry, Vol: 16, Pages: 1931-1940, ISSN: 1744-1560Mechanical frothing can be used to create gas–liquid monomer foams, which can then be subsequently polymerised to produce macroporous polymers. Until recently, this technique was limited to producing low porosity macroporous polymers with poor pore morphology and compression properties. In this study, we show that high porosity (75–80%) biobased macroporous polymers with excellent mechanical compression properties (E = 163 MPa, σ = 4.9 MPa) can be produced by curing of epoxy resin foams made by mechanical frothing. The key to this is to utilise the very viscous nature and very short working time of a biobased epoxy resin. It was found that increasing the frothing time of the biobased epoxy resin reduces the pore diameter of the resulting macroporous polymers. These macroporous polymers were also found to be partially interconnected. The compression properties of the macroporous polymers with smaller average pore diameter were found to be higher than those of foams with larger pore diameters. Unlike emulsion templating, which uses high internal phase emulsions to produce macroporous polymers, called polyHIPEs, the mechanical frothing technique has the advantage of creating macroporous polymers from monomers which cannot be easily emulsified.
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Journal articleTang M, Purcell M, Steele JAM, et al., 2013,
Porous Copolymers of ε-Caprolactone as Scaffolds for Tissue Engineering
, MACROMOLECULES, Vol: 46, Pages: 8136-8143, ISSN: 0024-9297- Author Web Link
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- Citations: 34
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Journal articleSeydibeyoglu MO, Misra M, Mohanty A, et al., 2013,
Green polyurethane nanocomposites from soy polyol and bacterial cellulose
, JOURNAL OF MATERIALS SCIENCE, Vol: 48, Pages: 2167-2175, ISSN: 0022-2461- Author Web Link
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- Citations: 43
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Journal articleLee K-Y, Qian H, Tay FH, et al., 2013,
Bacterial cellulose as source for activated nanosized carbon for electric double layer capacitors
, JOURNAL OF MATERIALS SCIENCE, Vol: 48, Pages: 367-376, ISSN: 0022-2461- Author Web Link
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- Citations: 44
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Journal articleQuero F, Eichhorn SJ, Nogi M, et al., 2012,
Interfaces in Cross-Linked and Grafted Bacterial Cellulose/Poly(Lactic Acid) Resin Composites
, JOURNAL OF POLYMERS AND THE ENVIRONMENT, Vol: 20, Pages: 916-925, ISSN: 1566-2543- Author Web Link
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- Citations: 41
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Journal articleLee K-Y, Bharadia P, Blaker JJ, et al., 2012,
Short sisal fibre reinforced bacterial cellulose polylactide nanocomposites using hairy sisal fibres as reinforcement
, COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING, Vol: 43, Pages: 2065-2074, ISSN: 1359-835X- Author Web Link
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- Citations: 55
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Journal articleLee K, Tang M, Williams CK, et al., 2012,
Carbohydrate derived copoly(lactide) as the compatibilizer for bacterial cellulose reinforced polylactide nanocomposites
, Composites Science and Technology, Vol: 72, Pages: 1646-1650, ISSN: 0266-3538A novel, entirely bio-derived polylactide carbohydrate copolymer (RP1) is used as a compatibilizer, to produce bacterial cellulose (BC) poly(l-lactide) (PLLA) nanocomposites with improved mechanical properties. Contact angle measurements of RP1 droplets on single BC nanofibres proved that it has a higher affinity towards BC than PLLA. RP1 has a comparable Young’s modulus, but lower tensile strength, than PLLA. When RP1 was blended with PLLA at a concentration of 5 wt%, the tensile modulus and strength of the resulting polymer blend decreased from 4.08 GPa and 63.1, respectively, for PLLA to 3.75 GPa and 56.1 MPa. A composite of BC and PLLA (with 5 wt% RP1 and 5 wt% BC) has a higher Young’s modulus and tensile strength, compared to either pure PLLA or PLLA–BC nanocomposites.
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Journal articleBismarck A, Burgstaller C, Lee KY, et al., 2012,
Recent Progress in Natural Fibre Composites: Selected Papers from the 3rd International Conference on Innovative Natural Fibre Composites for Industrial Applications, Ecocomp 2011 and BEPS 2011
, JOURNAL OF BIOBASED MATERIALS AND BIOENERGY, Vol: 6, Pages: 343-345, ISSN: 1556-6560- Author Web Link
- Cite
- Citations: 5
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Journal articleLee K-Y, Tammelin T, Schulfter K, et al., 2012,
High Performance Cellulose Nanocomposites: Comparing the Reinforcing Ability of Bacterial Cellulose and Nanofibrillated Cellulose
, ACS APPLIED MATERIALS & INTERFACES, Vol: 4, Pages: 4078-4086, ISSN: 1944-8244- Author Web Link
- Cite
- Citations: 180
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Journal articleLee K-Y, Ho KKC, Schlufter K, et al., 2012,
Hierarchical composites reinforced with robust short sisal fibre preforms utilising bacterial cellulose as binder
, Composites Science and Technology, Vol: 72, Pages: 1479-1486, ISSN: 0266-3538A novel robust non-woven sisal fibre preform was manufactured using a papermaking process utilising nanosized bacterial cellulose (BC) as binder for the sisal fibres. It was found that BC provides significant mechanical strength to the sisal fibre preforms. This can be attributed to the high stiffness and strength of the BC network. Truly green non-woven fibre preform reinforced hierarchical composites were prepared by infusing the fibre preforms with acrylated epoxidised soybean oil (AESO) using vacuum assisted resin infusion, followed by thermal curing. Both the tensile and flexural properties of the hierarchical composites showed significant improvements over polyAESO and neat sisal fibre preform reinforced polyAESO. These results were corroborated by the thermo-mechanical behaviour of the (hierarchical) composites, which showed an increased storage modulus and enhanced fibre–matrix stress transfer. Micromechanical modelling was also performed on the (hierarchical) composites. By using BC as binder for short sisal fibres, added benefits such as the high Young’s modulus of BC, enhanced fibre–fibre and fibre–matrix stress transfer can be utilised in the resulting hierarchical composites.
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Journal articleLee K-Y, Bismarck A, 2012,
Susceptibility of never-dried and freeze-dried bacterial cellulose towards esterification with organic acid
, CELLULOSE, Vol: 19, Pages: 891-900, ISSN: 0969-0239- Author Web Link
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- Citations: 47
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Book chapterShamsuddin S-R, Ho KKC, Lee K-Y, et al., 2012,
Carbon fibres: Properties, testing and analysis
, Wiley Encyclopedia of Composites, 5 Volume Set, Editors: Nicolais, Borzacchiello, Lee, Publisher: Wiley, ISBN: 9780470128282Written by prominent international experts from industry and academia, the Wiley Encyclopedia of Composites, Second Edition presents over 260 new and revised articles addressing the new technological advances in properties, processing, ...
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PatentLee K-Y, Bharadia P, Bismarck A, 2012,
Nanocellulose surface coated support material
, US9193130 -
Journal articleEge D, Lee K, Bismarck A, et al., 2012,
Evaluation of the degradation properties of carbonate substituted hydroxyapatite-poly(ε-caprolactone) composites
, Key Engineering Materials, Vol: 493-494, Pages: 120-125, ISSN: 1013-9826The aim of this work is to produce and characterise carbonate substituted hydroxyapatite (CHA) reinforced polycaprolactone (PCL) nanocomposites with a controlled degradation rate in order to match the rate of bone in-growth. The ideal degradation time for this purpose is estimated to be around 5-6 months however, in vivo, PCL degrades over a period of 2 to 3 years. It has been reported that NaOH surface treatment can accelerate the degradation of PCL [1-3]. In order to further modify the degradation rate of PCL, the effects of the incorporation of different volume fractions of CHA in samples surface treated with NaOH was investigated. CHA was produced by wet chemical synthesis. Samples comprising 8, 19, 25 wt% uncalcined CHA-PCL composites were produced by twin screw extrusion which were then injection moulded into cylinders. In order to accelerate the degradation rate of PCL, it was surface treated with 5 M NaOH for 3 days prior to PBS studies. The degradation profile was examined by % weight loss and % water uptake measurements. NaOH treatment was observed to erode the polymer surface and the polymer-filler interface. On subsequently degrading the pre-treated samples in PBS, it was observed that with increasing fraction of CHA, the degradation rate in PBS of the sample increased. Up to 8 wt % CHA filler there appeared to be little change in the degradation properties of the NaOH treated samples with the onset occurring after 60 days. However there was a marked acceleration of degradation for samples containing 19 wt% when degradation appeared to occur immediately. In conclusion, the addition of CHA significantly affects the behaviour of PCL. © (2012) Trans Tech Publications.
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Journal articleLee K-Y, Quero F, Blaker JJ, et al., 2011,
Surface only modification of bacterial cellulose nanofibres with organic acids
, CELLULOSE, Vol: 18, Pages: 595-605, ISSN: 0969-0239- Author Web Link
- Cite
- Citations: 159
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Book chapterLee K-Y, Delille A, Bismarck A, 2011,
Greener surface treatments of natural fiber reinforcements for use in the production of composite materials
, Cellulose Fibers: Bio- and Nano-Polymer Composites, Editors: Kalia, Kaith, Kaur, Publisher: Springer Science & Business Media, ISBN: 9783642173707This handbook deals with cellulose fibers and nano-fibers and covers the latest advances in bio- and nano- polymer composite materials.
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