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| 2. |
- Azizi Samir, M. A. S., et al.
(författare)
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High performance nanocomposite polymer electrolytes
- 2006
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Ingår i: Composite interfaces (Print). - : Informa UK Limited. - 0927-6440 .- 1568-5543. ; 13:4-6, s. 545-559
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Tidskriftsartikel (refereegranskat)abstract
- Solid lithium-conducting nanocomposite polymer electrolytes based on poly(oxyethylene) (POE) were prepared using high aspect ratio cellulosic whiskers and lithium imide salt, LiTFSI. The cellulosic whiskers were extracted from tunicate - a sea animal - and consisted of slender parallelepiped rods that have an average length around 1 μm and a width close to 15 nm. High performance nanocomposite electrolytes were obtained. The filler provided a high reinforcing effect, despite the favorable cellulose/POE interactions that were expected to decrease the possibility of interwhisker connection and formation of a percolating cellulosic network, while a high level of ionic conductivity was retained with respect to unfilled polymer electrolytes. Cross-linking and plasticizing of the matrix as well as preparation of the composites from an organic medium were also investigated.
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| 3. |
- Azizi Samir, M. A. S., et al.
(författare)
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Review of recent research into cellulosic whiskers, their properties and their application in nanocomposite field
- 2005
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 6:2, s. 612-626
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Tidskriftsartikel (refereegranskat)abstract
- There are numerous examples where animals or plants synthesize extracellular high-performance skeletal biocomposites consisting of a matrix reinforced by fibrous biopolymers. Cellulose, the world's most abundant natural, renewable, biodegradable polymer, is a classical example of these reinforcing elements, which occur as whiskerlike microfibrils that are biosynthesized and deposited in a continuous fashion. In many cases, this mode of biogenesis leads to crystalline microfibrils that are almost defect-free, with the consequence of axial physical properties approaching those of perfect crystals. This quite "primitive" polymer can be used to create high performance nanocomposites presenting outstanding properties. This reinforcing capability results from the intrinsic chemical nature of cellulose and from its hierarchical structure. Aqueous suspensions of cellulose crystallites can be prepared by acid hydrolysis of cellulose. The object of this treatment is to dissolve away regions of low lateral order so that the water-insoluble, highly crystalline residue may be converted into a stable suspension by subsequent vigorous mechanical shearing action. During the past decade, many works have been devoted to mimic biocomposites by blending cellulose whiskers from different sources with polymer matrixes.
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| 4. |
- Olsson, Richard T., et al.
(författare)
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Making flexible magnetic aerogels and stiff magnetic nanopaper using cellulose nanofibrils as templates
- 2010
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Ingår i: Nature Nanotechnology. - 1748-3387. ; 5:8, s. 584-588
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Tidskriftsartikel (refereegranskat)abstract
- Nanostructured biological materials inspire the creation of materials with tunable mechanical properties(1-3). Strong cellulose nanofibrils derived from bacteria(4) or wood(5,6) can form ductile or tough networks(7,8) that are suitable as functional materials(9,10). Here, we show that freeze-dried bacterial cellulose nanofibril aerogels can be used as templates for making lightweight porous magnetic aerogels, which can be compacted into a stiff magnetic nanopaper. The 20-70-nm-thick cellulose nanofibrils act as templates for the non-agglomerated growth of ferromagnetic cobalt ferrite nanoparticles(11) (diameter, 40-120 nm). Unlike solvent-swollen gels(12) and ferrogels(13-15), our magnetic aerogel is dry, lightweight, porous (98%), flexible, and can be actuated by a small household magnet. Moreover, it can absorb water and release it upon compression. Owing to their flexibility, high porosity and surface area, these aerogels are expected to be useful in microfluidics devices and as electronic actuators.
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| 5. |
- Olsson, R T, et al.
(författare)
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Making flexible magnetic aerogels and stiff magnetic nanopaper using cellulose nanofibrils as templates
- 2010
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Ingår i: Nature Nanotechnology. - : Springer Science and Business Media LLC. - 1748-3387 .- 1748-3395. ; 5, s. 584-588
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Tidskriftsartikel (refereegranskat)abstract
- Nanostructured biological materials inspire the creation of materials with tunable mechanical properties. Strong cellulose nanofibrils derived from bacteria or wood can form ductile or tough networks that are suitable as functional materials. Here, we show that freeze-dried bacterial cellulose nanofibril aerogels can be used as templates for making lightweight porous magnetic aerogels, which can be compacted into a stiff magnetic nanopaper. The 20-70-nm-thick cellulose nanofibrils act as templates for the non-agglomerated growth of ferromagnetic cobalt ferrite nanoparticles (diameter, 40-120 nm). Unlike solvent-swollen gels and ferrogels, our magnetic aerogel is dry, lightweight, porous (98%), flexible, and can be actuated by a small household magnet. Moreover, it can absorb water and release it upon compression. Owing to their flexibility, high porosity and surface area, these aerogels are expected to be useful in microfluidics devices and as electronic actuators.
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| 6. |
- Svagan, Anna, 1979-, et al.
(författare)
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Biomimetic Foams of High Mechanical Performance Based on Nanostructured Cell Walls Reinforced by Native Cellulose Nanofibrils
- 2008
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Ingår i: Advanced Materials. - Weinheim : Wiley-VCH Verlag GmbH. - 0935-9648 .- 1521-4095. ; 20:7, s. 1263-1269
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Tidskriftsartikel (refereegranskat)abstract
- A bioinspired foam in which cellulose nanofibrils are used to reinforce cell walls (ca. 3 mu m) is presented. The nanocomposite foams are prepared by a lyophilization technique and show composite structure at the cell-wall scale. The nanocellulosic network shows remarkable mechanical performance, expressed in much-improved modulus and yield strength compared with the neat starch foam.
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| 7. |
- Svagan, Anna, et al.
(författare)
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Biomimetic polysaccharide nanocomposites of high cellulose content and high toughness
- 2007
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 8:8, s. 2556-2563
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Tidskriftsartikel (refereegranskat)abstract
- Plant cell walls combine mechanical stiffness, strength and toughness despite a highly hydrated state. Inspired by this, a nanostructured cellulose network is combined with an almost viscous polysaccharide matrix in the form of a 50/50 amylopectin-glycerol blend. Homogeneous films with a microfibrillated cellulose (MFC) nanofiber content in the range of 10-70 wt % are successfully cast. Characterization is carried out by dynamic mechanical analysis, field-emission scanning electron microscopy, X-ray diffraction, and mercury density measurements. The MFC is well dispersed and predominantly oriented random-in-the-plane. High tensile strength is combined with high modulus and very high work of fracture in the nanocomposite with 70 wt % WC. The reasons for this interesting combination of properties include nanofiber and matrix properties, favorable nanofiber-matrix interaction, good dispersion, and the ability of the MFC network to maintain its integrity to a strain of at least 8%.
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