| 1. |
- Ait Benhamou, Anass, et al.
(författare)
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Strong and Flame-Resistant Nanocellulose Sheets Derived from Agrowastes via a Papermaking-Assisted Process
- 2024
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Ingår i: acs applied polymer materials. - 2637-6105. ; 6:5, s. 2763-2776
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Tidskriftsartikel (refereegranskat)abstract
- In recent decades, the production of nanocellulose has gained significant attention. Nanocellulose-based film materials have found widespread applications in various high-end sectors owing to their remarkable characteristics. Nevertheless, the limitation of certain functional properties, such as resistance to water and fire, has posed challenges to their broader utilization. In this study, we conducted a comparative investigation on the impact of two distinct chemical modifications, namely, TEMPO-mediated oxidation and phosphorylation, on the production of nanocellulose sheets via a papermaking-assisted process. This approach explores the synergistic effects of these modifications in enhancing the properties of cellulose nanofibers for nanopaper production. To achieve this, we proposed utilizing Henna stems as an alternative source of cellulosic material, aiming to harness untapped agricultural residues as a sustainable alternative to conventional sources such as wood and cotton. The phosphorylated Henna nanopaper exhibited substantial enhancements in terms of mechanical properties, wettability, fire resistance, and water vapor permeability when compared to the TEMPO-modified Henna nanopaper. In conclusion, our findings underscore the potential of Henna stems as an environmentally sustainable source of cellulose for nanofiber production, positioning it as a promising alternative to wood and other lignocellulosic sources for advanced applications.
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| 2. |
- Berglund, Lars, et al.
(författare)
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Cellulose-based materials comprising nanofibrillated cellulose from native cellulose
- 2011
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Patent (populärvet., debatt m.m.)abstract
- The present invention relates to cellulose-based materials comprising nanofibrillated cellulose (NFC) from native cellulose. exhibiting highly superior properties as compared to other cellulose-based materials, a method for preparing such cellulose-based material, and uses thereof are also disclosed.
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| 3. |
- Boujemaoui, Assya, et al.
(författare)
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Facile Preparation Route for Nanostructured Composites : Surface-Initiated Ring-Opening Polymerization of epsilon-Caprolactone from High-Surface-Area Nanopaper
- 2012
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 4:6, s. 3191-3198
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Tidskriftsartikel (refereegranskat)abstract
- In this work, highly porous nanopaper, i.e., sheets of papers made from non-aggregated nanofibrillated cellulose (NFC), have been surface-grafted with poly(epsilon-caprolactone) (PCL) by surface-initiated ring-opening polymerization (SI-ROP). The nanopaper has exceptionally high surface area (similar to 300 m(2)/g). The "grafting from" of the nanopapers was compared to "grafting from" of cellulose in the form of filter paper, and in both cases either titanium n-butoxide (Ti(On-Bu)(4)) or tin octoate (Sn(Oct)(2)) was utilized as a catalyst. It was found that a high surface area leads to significantly higher amount of grafted PCL in the substrates when Sn(Oct)2 was utilized as a catalyst. Up to 79 wt % PCL was successfully grafted onto the nanopapers as compared to filter paper where only 2-3 wt % PCL was grafted. However, utilizing Ti(On-Bu)4 this effect was not seen and the grafted amount was essentially similar, irrespectively of surface area. The mechanical properties of the grafted nanopaper proved to be superior to those of pure PCL films, especially at elevated temperatures. The present bottom-up preparation route of NFC-based composites allows high NFC content and provides excellent nanostructural control. This is an important advantage compared with some existing preparation routes where dispersion of the filler in the matrix is challenging.
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| 4. |
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| 5. |
- Cobut, Aline, et al.
(författare)
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Cellulose Nanocomposites by Melt Compounding of TEMPO-Treated Wood Fibers in Thermoplastic Starch Matrix
- 2014
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Ingår i: BioResources. - : BioResources. - 1930-2126. ; 9:2, s. 3276-3289
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Tidskriftsartikel (refereegranskat)abstract
- To facilitate melt compounding of cellulose nanofibrils (CNF) based composites, wood pulp fibers were subjected to a chemical treatment whereby the fibers were oxidized using 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO). This treatment introduced negatively charged carboxylate groups to the fibers. TEMPO-treated fibers (TempoF) were added to a mixture of amylopectin starch, glycerol, and water. Granules were prepared from this mixture and processed into CNF composites by extrusion. TempoF were easier to process into composites as compared with non-treated pulp fibers (PF). SEM revealed partial disintegration of TempoF during melt processing. Consequently, TempoF gave composites with much better mechanical properties than those of conventional composites prepared from pulp fibers and TPS. Particularly, at 20 wt% TempoF content in the composite, the modulus and strength were much improved. Such a continuous melt processing route, as an alternative to laboratory solvent casting techniques, may promote large-scale production of CNF-based composites as an environmentally friendly alternative to synthetic plastics/composites.
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| 6. |
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| 7. |
- Kochumalayil, Joby, et al.
(författare)
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Tamarind seed xyloglucan : a thermostable high-performance biopolymer from non-food feedstock
- 2010
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Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 20:21, s. 4321-4327
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Tidskriftsartikel (refereegranskat)abstract
- Polysaccharide biopolymers from renewable resources are of great interest as replacements for petroleum-based polymers since they have lower cradle-to-grave non-renewable energy use and greenhouse gas emissions. Starch is widely used as a packaging material but is based on food resources such as potato or corn, and suffers from high sensitivity to water vapor even under ambient conditions. For the first time, xyloglucan (XG) from tamarind seed waste is explored as an alternative high-performance biopolymer from non-food feedstock. XG is purified, and dissolved in water to cast films. Moisture sorption isotherms, tensile tests and dynamic mechanical thermal analysis are performed. Glycerol plasticization toughening and enzymatic modification (partial removal of galactose in side chains of XG) are attempted as means of modification. XG films show much lower moisture sorption than the amylose component in starches. Stiffness and strength are very high, with considerable ductility and toughness. The thermal stability is exceptionally high and is approaching 250 degrees C. Glycerol plasticization is effective already at 10% glycerol. These observations point towards the potential of XG as a "new'' biopolymer from renewable non-food plant resources for replacement of petroleum-based polymers.
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| 8. |
- Kochumalayil, Joby, et al.
(författare)
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Xyloglucan films
- 2009
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Patent (populärvet., debatt m.m.)abstract
- The present invention pertains to films comprising xyloglucan, processes for preparing films comprising xyloglucan, as well as various uses of said films as for instance packaging material. Specifically, the present invention relates to xyloglucan films having advantageous properties relating to inter alia tensile strength, elastic modulus, and strain-to-failure.
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| 9. |
- Lindström, Stefan, et al.
(författare)
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Mechanosorptive creep in nanocellulose materials
- 2012
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Ingår i: Cellulose. - : Springer. - 0969-0239 .- 1572-882X. ; 19:3, s. 809-819
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Tidskriftsartikel (refereegranskat)abstract
- The creep behavior of nanocellulose films and aerogels are studied in a dynamic moisture environment, which is crucial to their performance in packaging applications. For these materials, the creep rate under cyclic humidity conditions exceeds any constant humidity creep rate within the cycling range, a phenomenon known as mechanosorptive creep. By varying the sample thickness and relative humidity ramp rate, it is shown that mechanosorptive creep is not significantly affected by the through-thickness moisture gradient. It is also shown that cellulose nanofibril aerogels with high porosity display the same accelerated creep as films. Microstructures larger than the fibril diameter thus appear to be of secondary importance to mechanosorptive creep in nanocellulose materials, suggesting that the governing mechanism is found between molecular scales and the length-scales of the fibril diameter.
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| 10. |
- Liu, Peng, et al.
(författare)
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Cellulose and chitin nanomaterials for capturing silver ions (Ag+) from water via surface adsorption
- 2014
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Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 21:1, s. 449-461
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Tidskriftsartikel (refereegranskat)abstract
- The study explores the potential of cellulose nanocrystals (CNC), cellulose nanofibers (CNF) and chitin nanocrystals (ChNC) isolated from bioresidues to remove silver ions from contaminated water. Zeta sizer studies showed negatively charged surfaces for CNC and CNF isolated from cellulose sludge in the acidic and alkaline pHs, whereas ChNC isolated from crab shell residue showed either positive or negative charges depending on pH conditions. Model water containing silver ions showed a decrease in Ag+ ion concentration (measured by inductively coupled plasma-optical emission spectrometer; inductively coupled plasma mass spectrometry), after treatment with CNC, CNF and ChNC suspensions. The highest Ag+ ion removal was measured near neutral pH for CNC, being 34.4 mg/g, corresponding to 64 % removal. ChNC showed 37 % and CNF showed 27 % removal of silver ions. The WDX (wavelength dispersive X-ray analysis) and XPS (X-ray photoelectron spectroscopy) analysis confirmed the presence of silver ions on the surface of the nanocellulose and nanochitin after adsorption. Surface adsorption on the nanoparticles via electrostatic interactions is considered to be the prominent mechanism of heavy metal ion capture from aqueous medium, with CNC with negative surface charge and negatively charged functional groups being most favourable for the adsorption of positively charged Ag+ ions compared to other native bionanomaterials
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