| 1. |
- Berglund, Linn, et al.
(författare)
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Toward eco-efficient production of natural nanofibers from industrial residue : Eco-design and quality assessment
- 2020
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Ingår i: Journal of Cleaner Production. - : Elsevier. - 0959-6526 .- 1879-1786. ; 255
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Tidskriftsartikel (refereegranskat)abstract
- Conversion of bio-based industrial residues into high value-added products such as natural nanofibers is advantageous from an environmental and economic perspective, promoting resource efficiency along with the utilization of renewable materials. However, in order to employ the benefits of the raw material; its eco-efficient production should further be developed. Within this context, eco-design optimization through life cycle assessment (LCA) combined with life cycle costing (LCC) were applied to target eco-efficient production of natural nanofibers from carrot residue, along with quality assessment. The initial production steps included pretreatment combined mechanical nanofibrillation via ultrafine grinding, where the largest contributors to the environmental impact were identified as chemicals and energy. These were targeted by omitting the alkali pretreatment step and instead applying direct bleaching prior to nanofibrillation. After eco-design optimization, the yield increased while the energy, chemical, and water use significantly decreased. Therefore, a reduced environmental impact of more than 75% each for carbon footprint, freshwater ecotoxicity, and human toxicity was shown, along with a cost reduction of more than 50%. The use of carrot residue displayed an efficient conversion into natural nanofibers that was further promoted with the use of eco-design, yet with sustained functionality and nanoscaled dimensions, thus promoting resource-efficiency and natural nanofiber implementation in a wide range of promising bio-based applications.
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| 2. |
- Berglund, Linn, et al.
(författare)
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Utilizing the Natural Composition of Brown Seaweed for the Preparation of Hybrid Ink for 3D Printing of Hydrogels
- 2020
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Ingår i: ACS Applied Bio Materials. - : American Chemical Society (ACS). - 2576-6422. ; 3:9, s. 6510-6520
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Tidskriftsartikel (refereegranskat)abstract
- This study aims to utilize the natural composition of brown seaweed by deriving alginate and cellulose concurrently from the stipe (stem-like) and blade (leaf-like) structures of the seaweed; further, this is followed by fibrillation for the direct and resource-efficient preparation of alginate/cellulose nanofiber (CNF) hybrid inks for three-dimensional (3D) printing of hydrogels. The efficiency of the fibrillation process was evaluated, and the obtained gels were further studied with regard to their rheological behavior. As a proof of concept, the inks were 3D printed into discs, followed by cross-linking with CaCl2 to form biomimetic hydrogels. It was shown that the nanofibrillation process from both seaweed structures is very energy-efficient, with an energy demand lower than 1.5 kW h/kg, and with CNF dimensions below 15 nm. The inks displayed excellent shear-thinning behavior and cytocompatibility and were successfully printed into 3D discs that, after cross-linking, exhibited an interconnected network structure with favorable mechanical properties, and a cell viability of 71%. The designed 3D biomimetic hydrogels offers an environmentally benign, cost-efficient, and biocompatible material platform with a favorable structure for the development of biomedical devices, such as 3D bio printing of soft tissues.
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| 3. |
- Butylina, Svetlana, et al.
(författare)
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Cellulose Nanocomposite Hydrogels : From Formulation to Material Properties
- 2020
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Ingår i: Frontiers in Chemistry. - : Frontiers Media S.A.. - 2296-2646. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Poly(vinyl alcohol) (PVA) hydrogels produced using the freeze-thaw method have attracted attention for a long time since their first preparation in 1975. Due to the importance of polymer intrinsic features and the advantages associated with them, they are very suitable for biomedical applications such as tissue engineering and drug delivery systems. On the other hand, there is an increasing interest in the use of biobased additives such as cellulose nanocrystals, CNC. This study focused on composite hydrogels which were produced by using different concentrations of PVA (5 and 10%) and CNC (1 and 10 wt.%), also, pure PVA hydrogels were used as references. The main goal was to determine the impact of both components on mechanical, thermal, and water absorption properties of composite hydrogels as well as on morphology and initial water content. It was found that PVA had a dominating effect on all hydrogels. The effect of the CNC addition was both concentration-dependent and case-dependent. As a general trend, addition of CNC decreased the water content of the prepared hydrogels, decreased the crystallinity of the PVA, and increased the hydrogels compression modulus and strength to some extent. The performance of composite hydrogels in a cyclic compression test was studied; the hydrogel with low PVA (5) and high CNC (10) content showed totally reversible behavior after 10 cycles.
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| 4. |
- Geng, Shiyu, et al.
(författare)
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Large-scale manufacturing of ultra-strong, strain-responsive poly(lactic acid)-based nanocomposites reinforced with cellulose nanocrystals
- 2020
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Ingår i: Composites Science And Technology. - : Elsevier. - 0266-3538 .- 1879-1050. ; 194
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Tidskriftsartikel (refereegranskat)abstract
- Developing materials from renewable resources to produce nanocomposites with satisfactory mechanical properties is a vital progress in today's society, and meanwhile, the widespread use of these nanocomposites needs to be enabled through large-scale manufacturing. Herein, ultra-strong nanocomposites with an aligned structure that consisted of bio-based, biodegradable poly(lactic acid) (PLA) and cellulose nanocrystals are demonstrated, and these nanocomposites can be manufactured at a large scale through surface modification of the nanocrystals, liquid-assisted extrusion, and solid-state drawing. An ultimate strength of 353 MPa and a toughness of 107 MJ/m3 can be achieved by these nanocomposites, which are superior compared to the values of many other thermoplastic materials. The mechanism that explains the high toughness of these nanocomposites has been extensively investigated, revealing that sliding of the PLA crystallites present in the materials is the main factor. Moreover, these nanocomposites possess relatively high glass transition temperature and exhibit strain-responsive birefringence behavior, which indicates their great potential in not only structural applications, but also optical strain sensing areas.
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| 5. |
- Geng, Shiyu, et al.
(författare)
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Multifunctional Carbon Aerogels with Hierarchical Anisotropic Structure Derived from Lignin and Cellulose Nanofibers for CO2 Capture and Energy Storage
- 2020
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 12:6, s. 7432-7441
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Tidskriftsartikel (refereegranskat)abstract
- In current times, CO2 capture and light-weight energy storage are receiving significant attention and will be vital functions in next-generation materials. Porous carbonaceous materials have great potential in these areas, whereas most of the developed carbon materials still have significant limitations, such as non-renewable resources, complex and costly processing or the absence of tailorable structure. In this study, a new strategy is developed for using the currently under-utilized lignin and cellulose nanofibers, which can be extracted from renewable resources to produce high-performance multifunctional carbon aerogels with a tailorable, anisotropic pore structure. Both the macro- and microstructure of the carbon aerogels can be simultaneously controlled by discreetly tuning the weight ratio of lignin to cellulose nanofibers in the carbon aerogel precursors, which considerably influences their final porosity and surface area. The designed carbon aerogels demonstrate excellent performance in both CO2 capture and capacitive energy storage, and the best results exhibit a CO2 adsorption capacity of 5.23 mmol g-1 at 273 K and 100 kPa, and a specific electrical double layer capacitance of 124 F g-1 at a current density of 0.2 A g-1, indicating that they have great future potential in the relevant applications.
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| 6. |
- Hassan, Mohammad L., et al.
(författare)
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Water purification ultrafiltration membranes using nanofibers from unbleached and bleached rice straw
- 2020
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- There has been an increasing interest in recent years in isolating cellulose nanofibers from unbleached cellulose pulps for economic, environmental, and functional reasons. In the current work, cellulose nanofibers isolated from high-lignin unbleached neutral sulfite pulp were compared to those isolated from bleached rice straw pulp in making thin-film ultrafiltration membranes by vacuum filtration on hardened filter paper. The prepared membranes were characterized in terms of their microscopic structure, hydrophilicity, pure water flux, protein fouling, and ability to remove lime nanoparticles and purify papermaking wastewater effluent. Using cellulose nanofibers isolated from unbleached pulp facilitated the formation of a thin-film membrane (with a shorter filtration time for thin-film formation) and resulted in higher water flux than that obtained using nanofibers isolated from bleached fibers, without sacrificing its ability to remove the different pollutants.
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| 7. |
- Jonasson, Simon, et al.
(författare)
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Isolation and characterization of cellulose nanofibers from aspen wood using derivatizing and non-derivatizing pretreatments
- 2020
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Ingår i: Cellulose. - : Springer. - 0969-0239 .- 1572-882X. ; 27:1, s. 185-203
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Tidskriftsartikel (refereegranskat)abstract
- The link between wood and corresponding cellulose nanofiber (CNF) behavior is complex owing the multiple chemical pretreatments required for successful preparation. In this study we apply a few pretreatments on aspen wood and compare the final CNF behavior in order to rationalize quantitative studies of CNFs derived from aspen wood with variable properties. This is relevant for efforts to improve the properties of woody biomass through tree breeding. Three different types of pretreatments were applied prior to disintegration (microfluidizer) after a mild pulping step; derivatizing TEMPO-oxidation, carboxymethylation and non-derivatizing soaking in deep-eutectic solvents. TEMPO-oxidation was also performed directly on the plain wood powder without pulping. Obtained CNFs (44–55% yield) had hemicellulose content between 8 and 26 wt% and were characterized primarily by fine (height ≈ 2 nm) and coarser (2 nm < height < 100 nm) grade CNFs from the derivatizing and non-derivatizing treatments, respectively. Nanopapers from non-derivatized CNFs had higher thermal stability (280 °C) compared to carboxymethylated (260 °C) and TEMPO-oxidized (220 °C). Stiffness of nanopapers made from non-derivatized treatments was higher whilst having less tensile strength and elongation-at-break than those made from derivatized CNFs. The direct TEMPO-oxidized CNFs and nanopapers were furthermore morphologically and mechanically indistinguishable from those that also underwent a pulping step. The results show that utilizing both derivatizing and non-derivatizing pretreatments can facilitate studies of the relationship between wood properties and final CNF behavior. This can be valuable when studying engineered trees for the purpose of decreasing resource consumption when isolation cellulose nanomaterials.
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| 8. |
- López-Rubio, Amparo, et al.
(författare)
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Strategies to Improve the Properties of Amaranth Protein Isolate-Based Thin Films for Food Packaging Applications : Nano-Layering through Spin-Coating and Incorporation of Cellulose Nanocrystals
- 2020
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Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 10:12
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Tidskriftsartikel (refereegranskat)abstract
- In this work, two different strategies for the development of amaranth protein isolate (API)-based films were evaluated. In the first strategy, ultrathin films were produced through spin-coating nanolayering, and the effects of protein concentration in the spin coating solution, rotational speed, and number of layers deposited on the properties of the films were evaluated. In the second strategy, cellulose nanocrystals (CNCs) were incorporated through a casting methodology. The morphology, optical properties, and moisture affinity of the films (water contact angle, solubility, water content) were characterized. Both strategies resulted in homogeneous films with good optical properties, decreased hydrophilic character (as deduced from the contact angle measurements and solubility), and improved mechanical properties when compared with the neat API-films. However, both the processing method and film thickness influenced the final properties of the films, being the ones processed through spin coating more transparent, less hydrophilic, and less water-soluble. Incorporation of CNCs above 10% increased hydrophobicity, decreasing the water solubility of the API films and significantly enhancing material toughness.
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| 9. |
- Rosenstock Völtz, Luísa, 1988-, et al.
(författare)
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The Effect of Recycling on Wood-Fiber Thermoplastic Composites
- 2020
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Ingår i: Polymers. - : MDPI. - 2073-4360. ; 12:8
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the effect of recycling on polypropylene (PP) and wood-fiber thermoplastic composites (WPCs) using a co-rotating twin-screw extruder. After nine extrusion passes microscopy studies confirmed that the fiber length decreased with the increased number of recycling passes but the increased processing time also resulted in excellent dispersion and interfacial adhesion of the wood fibers in the PP matrix. Thermal, rheological, and mechanical properties were studied. The repeated extrusion passes had minimal effect on thermal behavior and the viscosity decreased with an increased number of passes, indicating slight degradation. The recycling processes had an effect on the tensile strength of WPCs while the effect was minor on the PP. However, even after the nine recycling passes the strength of WPC was considerably better (37 MPa) compared to PP (28 MPa). The good degree of property retention after recycling makes this recycling strategy a viable alternative to discarding the materials. Thus, it has been demonstrated that, by following the most commonly used extrusion process, WPCs can be recycled several times and this methodology can be industrially adapted for the manufacturing of recycled products.
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| 10. |
- Sepahvand, Sima, et al.
(författare)
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A promising process to modify cellulose nanofibers for carbon dioxide (CO2) adsorption
- 2020
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Ingår i: Carbohydrate Polymers. - : Elsevier. - 0144-8617 .- 1879-1344. ; 230
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Tidskriftsartikel (refereegranskat)abstract
- A novel process of using phthalimide to modify cellulose nanofibers (CNF) for CO2 adsorption was studied. The effectiveness of the modification was confirmed by ATR-IR. Phthalimide incorporation onto CNF was confirmed with the characteristic peaks of NH2, C–N, and ester bonding COO− was observable. The XPS analyses confirmed the presence of N1s peak in Ph-CNF, meaning that the hydroxyl groups reacted with the amino groups (NH2) of phthalimide on the CNF surface. Based on the results, surface modification and addition of phthalimide increased the specific surface area, but also decreased the overall porosity, size of pores and volume of pores. When the temperature, humidity, pressure, and airflow rate increased, the CO2 adsorption significantly increased. The CO2 adsorption of phthalimide-modified CNF was confirmed by ATR-IR spectroscopy as the characteristic peaks of HCO−3,NH+3 and ester bonding NCOO− were visible on the spectra.
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