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| 2. |
- Danyliv, Olesia, et al.
(författare)
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Self-Standing, Robust Membranes Made of Cellulose Nanocrystals (CNCs) and a Protic Ionic Liquid : Toward Sustainable Electrolytes for Fuel Cells
- 2021
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Ingår i: ACS Applied Energy Materials. - : American Chemical Society. - 2574-0962. ; 4:7, s. 6474-6485
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Tidskriftsartikel (refereegranskat)abstract
- Energy-conversion devices based on the phenomenon of proton conduction, for example, polymer electrolyte membrane fuel cells (PEMFCs), require low cost and sustainable electrolytes with high ionic conductivity and good mechanical properties under anhydrous conditions and at temperatures up to 150 °C. Biopolymers possess an intrinsic thermomechanical stability but an insufficient proton conductivity in the dry state, which however may be imparted by a protic ionic liquid (PIL). This work presents the preparation and properties of composite membranes made of cellulose nanocrystals (CNCs) and a PIL. The membranes are thermally stable and display an ionic conductivity within the range 10-4-10-3 S/cm for temperatures between 120 and 160 °C. Moreover, the analysis of the biopolymer's apparent dimensions at nanoscale reveals a dependence of the CNCs' defects, twisting, and aggregation in the presence of the PIL. Preliminary tests using a simple fuel cell setup demonstrate a response of the membranes to the inlet of H2 gas, with a generation of electrical current. These findings provide a solid groundwork for further development and future studies of biopolymer/PIL electrolytes for energy applications. © 2021 The Authors.
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| 3. |
- Kolman, Krzysztof, 1986, et al.
(författare)
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Combined Nanocellulose/Nanosilica Approach for Multiscale Consolidation of Painting Canvases
- 2018
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 1:5, s. 2036-2044
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Tidskriftsartikel (refereegranskat)abstract
- The restoration of painting canvases is a complex problem that, because of the hierarchical nature of the canvas, requires intervention at several length scales. We propose an approach combining polyelectrolyte-treated silica nanoparticles (SNP) and cellulose nanofibrils (CNF) for canvas consolidation. The formulations, applied on model degraded canvases, gave a total weight increase of
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| 4. |
- Nagalakshmaiah, M., et al.
(författare)
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Melt extrusion of polystyrene reinforced with cellulose nanocrystals modified using poly (styrene)-co-(2-ethylhexyl acrylate) latex particles
- 2017
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Ingår i: European Polymer Journal. - : Elsevier BV. - 0014-3057. ; 91, s. 297-306
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Tidskriftsartikel (refereegranskat)abstract
- Non-covalent modification of cellulose nanocrystals (CNC) was performed using a water based method with laboratory prepared statistical copolymer, viz. poly [(styrene)-co-(2-ethylhexyl acrylate)], by ionic interactions. The thermal, functional and morphological properties of modified CNC were characterized by thermogravimetric analysis (TGA), Fourier vansform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Their hydrophobic nature was investigated by contact angle measurements. These nanoparticles were used to prepare polystyrene (PS) nanocomposites by twin-screw extrusion. The thermomechanical performance of the ensuing composites was examined by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The morphology of the materials was also studied using scanning electron microscopy (SEM).
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| 5. |
- Nechyporchuk, Oleksandr, 1988, et al.
(författare)
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Accelerated ageing of cotton canvas as a model for further consolidation practices
- 2017
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Ingår i: Journal of Cultural Heritage. - : Elsevier BV. - 1296-2074. ; 28, s. 183-187
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Tidskriftsartikel (refereegranskat)abstract
- In order to assess the effectiveness of various practices for canvas consolidation, model substrates are needed. In this work, a method of rapid ageing of cotton canvas is described. The method consists of treatment of the canvas with a mixture of hydrogen peroxide and sulfuric acid at 40 degrees C during 72 hours to mimic to some extent the natural processes of oxidation and acid-catalysed hydrolysis of cellulose. Two protocols for canvas degradation were developed, which reduced the degree of polymerization of cellulose from ca.6250 to ca.1350 and 450. The reduction of the mechanical properties and the increase of the negative charge were also quantified. These samples were compared with a canvas degraded using a state-of-the-art method that takes up to 20 days. The results show that the developed method can provide a rapid procedure for preparing small samples for testing various consolidation strategies by conservators.
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| 6. |
- Nechyporchuk, Oleksandr, 1988, et al.
(författare)
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Cellulose Nanofibril-Based Coatings of Woven Cotton Fabrics for Improved Inkjet Printing with a Potential in E-Textile Manufacturing
- 2017
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Ingår i: ACS Sustainable Chemistry & Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 5:6, s. 4793-4801
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Tidskriftsartikel (refereegranskat)abstract
- The roughness of woven fabrics strongly limits print quality, which is particularly critical in printing of conductive circuits on fabrics. This work demonstrates the use of wood-derived cellulose nanofibrils (CNFs) mixed with a plasticizer as coatings of woven cotton fabrics for inkjet printing using (i) conventional water-based pigment inks and (ii) conductive silver nanoparticle inks. CNFs, being similar in nature to cotton, introduced minimal alteration to woven cotton fabrics by preserving their visual appearance as well as their mechanical properties. We also showed that the use of CNF-based coatings facilitated ink droplet settling on the substrate, which ensured high quality with the potential of higher printing speed production. The coatings of CNFs plasticized with glycerol enabled concentrating the pigment on the surface of the fabric, preventing its penetration into the fabric depth, which allows for increasing the resolution of the printed pattern. When used for color ink printing, it enhanced the print chroma and permitted reducing the amount of deposited ink, yielding similar color lightness. The CNF coatings allowed for substantial reduction of the amount of silver ink when printing the conductive tracks on fabrics. Furthermore, the nature of the coating imparts flexibility to the conductive layer, while maintaining electric signal quality, even when folded. This study provides a platform for manufacturing sustainable and disposable e-textiles.
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| 7. |
- Nechyporchuk, Oleksandr, 1988, et al.
(författare)
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Current Progress in Rheology of Cellulose Nanofibril Suspensions
- 2016
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 17:7, s. 2311-2320
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Forskningsöversikt (refereegranskat)abstract
- Cellulose nanofibrils (CNFs) are produced and commonly used in the form of aqueous suspensions or gels. A number of studies have focused lately on rheological properties of CNF suspensions, which gives insight into properties of such materials and can reflect their behavior during handling. This Review summarizes the recent progress in rheological studies on CNF aqueous suspensions using rotational rheometry. Here, we discuss linear viscoelastic properties, i.e., frequency-dependent storage and loss moduli; shear flow behavior, i.e., apparent viscosity and shear stress as a function of shear rate; local flow characteristics, etc. In this Review, we point out that the rheological behavior of at least two types of CNF suspensions should be distinguished: (i) ones produced using mechanical fibrillation with or without enzymatic pretreatment (no surface chemical modification), which possess highly flocculated structure, and (ii) ones produced involving chemical modification pretreatments, e.g., carboxylation, carboxymethylation, quaternization, or sulfonation, which possess better colloidal stability and do not evidently flocculate.
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| 8. |
- Nechyporchuk, Oleksandr, 1988, et al.
(författare)
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Production of cellulose nanofibrils: A review of recent advances
- 2016
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Ingår i: Industrial Crops and Products. - : Elsevier BV. - 0926-6690. ; 93, s. 2-25
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Forskningsöversikt (refereegranskat)abstract
- This review describes the recent advances-in production of cellulose nanofibrils (CNF), otherwise known as nanofibrillated cellulose (NFC), microfibrillated cellulose (MFC) or cellulose nanofibers, a material with significant barrier, mechanical and colloidal properties, low density, renewable and biodegradable character. The above properties make CNF promising for applications in such fields as papermaking, composites, packaging, coatings, biomedicine and automotive. In this review, CNF production methods are summarized, covering raw materials selection, structural and chemical aspects necessary for understanding the nanofibril extraction process, conventional and novel mechanical disintegration techniques, as well as biological and chemical pretreatments aimed at facilitating nanofibril isolation. The issues of fractionation, performed with the objective of retrieving the residual microscopic fiber fragments from CNF suspensions, are addressed. Additionally, the preparation of CNF in various forms, such as suspensions, water-redispersible powders, films or nanopapers, hydrogels and aerogels, is discussed.
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| 9. |
- Nechyporchuk, Oleksandr, 1988, et al.
(författare)
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Wet Spinning of Flame-Retardant Cellulosic Fibers Supported by Interfacial Complexation of Cellulose Nanofibrils with Silica Nanoparticles
- 2017
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Ingår i: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8252 .- 1944-8244. ; 9:44, s. 39069-39077
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Tidskriftsartikel (refereegranskat)abstract
- The inherent flammability of cellulosic fibers limits their use in some advanced applications. This work demonstrates for the first time the production of flame-retardant macroscopic fibers from wood-derived cellulose nanofibrils (CNF) and silica nanoparticles (SNP). The fibers are made by extrusion of aqueous suspensions of anionic CNF into a coagulation bath of cationic SNP at an acidic pH. As a result, the fibers with a CNF core and a SNP thin shell are produced through interfacial complexation. Silica-modified nanocellulose fibers with a diameter of ca. 15 ?m, a titer of ca. 3 dtex and a tenacity of ca. 13 cN tex-1 are shown. The flame retardancy of the fibers is demonstrated, which is attributed to the capacity of SNP to promote char forming and heat insulation on the fiber surface.
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| 10. |
- Palladino, Nicoletta, et al.
(författare)
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Nanomaterials for combined stabilisation and deacidification of cellulosic materials - the case of iron-tannate dyed cotton
- 2020
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Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- The conservation of textiles is a challenge due to the often fast degradation that results from the acidity combined with a complex structure that requires remediation actions to be conducted at several length scales. Nanomaterials have lately been used for various purposes in the conservation of cultural heritage. The advantage with these materials is their high efficiency combined with a great control. Here, we provide an overview of the latest developments in terms of nanomaterials-based alternatives, namely inorganic nanoparticles and nanocellulose, to conventional methods for the strengthening and deacidification of cellulose-based materials. Then, using the case of iron-tannate dyed cotton, we show that conservation can only be addressed if the mechanical strengthening is preceded by a deacidification step. We used CaCO3 nanoparticles to neutralize the acidity, while the stabilisation was addressed by a combination of nanocellulose, and silica nanoparticles, to truly tackle the complexity of the hierarchical nature of cotton textiles. Silica nanoparticles enabled strengthening at the fibre scale by covering the fibre surface, while the nanocellulose acted at bigger length scales. The evaluation of the applied treatments, before and after an accelerated ageing, was assessed by tensile testing, the fibre structure by SEM and the apparent colour changes by colourimetric measurements.
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