| 1. |
- Forsberg, Viviane, 1981-, et al.
(författare)
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Photodetector of multilayer exfoliated MoS2 deposited on polyimide films
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We fabricated a photodetector based on multilayer molybdenum disulfide (MoS2) by micromechanical cleavage of a molybdenite crystal using a polyimide film. We deposited 40 nm of gold by vacuum sputtering and copper tape was used for the contacts. Without any surface treatment, we achieved high responsivity at different incident optical power. The calculated responsivity was 23 mA/W of incident optical power in the range between 400 and 800 nm. For the responsivity measurement it was estimated that MoS2 have a bandgap of 1.6 eV, which lies between monolayer and multilayer films. The thickness of the MoS2 thin film was determined by Raman spectroscopy evaluating the difference between the in plane and out of plane Raman modes. The measurement of IV curves indicated Ohmic contacts in respect to the Au regardless of the incident optical power. Our device fabrication was much simpler than previous reported devices and can be used to test the light absorption and luminescence capabilities of exfoliated MoS2.
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| 2. |
- Fiskari, Juha, 1967-, et al.
(författare)
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Deep eutectic solvent delignification to low-energy mechanical pulp to produce papermaking fibers
- 2020
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Ingår i: BioResources. - 1930-2126. ; 15:3, s. 6023-6032
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Tidskriftsartikel (refereegranskat)abstract
- A novel process based on low-energy mechanical pulp and deep eutectic solvents (DESs) was evaluated with the goal of producing fibers suitable for papermaking. Ideally, these fibers could be produced at much lower costs, especially when applied to an existing paper mill equipped with a thermomechanical pulp (TMP) production line that was threatened with shutdown due to the decreasing demand for wood-containing paper grades. The efficiency of DES delignification in Teflon-coated autoclaves and in a specially designed non-standard flow extractor was evaluated. All tested DESs had choline chloride ([Ch]Cl) as the hydrogen bond acceptor. Lactic acid, oxalic acid, malic acid, or urea acted as hydrogen bond donors. The temperatures and times of the delignification tests were varied. Chemical analysis of the pulp samples revealed that DESs containing lactic acid, oxalic acid, or urea decreased the lignin content by approximately 50%. The DES delignification based on [Ch]Cl and urea exhibited good hemicellulose retention while DES systems based on organic acids resulted in varying hemicellulose losses. The [Ch]Cl / urea mixture did not appear to be corrosive to stainless steel, which was another advantage of this DES system.
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| 3. |
- Forsberg, Viviane, 1981-, et al.
(författare)
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Printability of functional inkjet inks onto commercial inkjet substrates and a taylor made pigmented coated paper
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Printed electronics are of increasing interest. The substrates used have primarily been plastics although the interest for cellulose-based substrates is increasing due to the environmental aspect as well as cost. The requirements of substrates for electronically active inks differs from graphical inks and therefore we have investigated a custom-made pigment based coated paper and compared it to commercial photo-papers and a coated PE film.Our goal with the study of different substrates was to select the most suitable substrate to print water based 2D materials inkjet inks for flexible electronics.The discovery of graphene, a layered material achieved from the exfoliation of graphite, has resulted in the study of other materials with similar properties to cover areas where graphene could not be used due to the absence of a bandgap in the material. For example in thin film transistors (TFT) a semiconductor layer is essential to enable turn on and off the device. This semiconductor layer can be achieved using various materials but particular interest have been dedicated to abundant and cheap 2D materials such as the transition metal dichalcogenide (TMD) molybdenum disulfide (MoS2). To date, most of the dispersions based on TMDs use organic solvents or water solutions of surfactants. Previously we focus on the study of environmental friendly inks produced by liquid phase exfoliation (LPE) of MoS2 in water using cellulose stabilizers such as ethyl cellulose (EC), cellulose nanofibrils (CNF) and nanofibrilcellulose (NFC). We have study various aspects of the ink fabrication includi ng pH range, the source of MoS2, nanosheets thickness, particle size distribution, ink stabilizers, ink concentration, viscosity and surface tension. These inks have very low concentration requiring a number of printing passes to cover the substrate. Therefore the substrate selection is crucial as a large amount of solvent is to be absorb by the substrate. Our goal was to use such an ink to print electrodes of MoS2 into a paper substrate after substrate selection.Commercial photo papers, a commercial coated PE film and a tailor made multilayer pigment coated paper substrate were used for the substrate selection analysis. We print the substrates using a DIMATIX inkjet printer with a 10 pL printing head using the distillated water waveform supplied by the printer manufacturer. The voltage used was 23V and 4 nozzles were used for the print outs. The inkjet ink used was the organic PEDOT:PSS. We printed lines ranging from 1 pixel to 20 pixels with 1, 2 and 3 printing passes. The printing quality was evaluated through measurements of the waviness of the printed lines measured after imaging the printed samples with a SEM microscope. The line width measurement was done using the software from the SEM.We also evaluated the structure of the coatings using SEM and topography measurements. The ink penetration through the substrates was evaluated using Raman Spectroscopy. For the pigmented coated sample we measured 4% of ink penetration through the substrate for the 1pxl printed line printed once onto the paper. Cross-section SEM images of the printed lines were made to visualize the ink penetration into the substrate.Regarding the electrical conductivity of the printed samples, the differences in resistivity varying the width of the printed lines and the number of printed passes were evaluated. The resistivity of the printed electrodes was evaluated using the 2-points probe method. Before the resistivity measurements, the printed substrates were heated at 50°C and 100°C for 30 minutes in an oven.We choose the PEDOT:PSS ink because it is a low price ink compared to metal nanoparticles inks for printed electronics. The print outs had low resistivity at a few printing passes with no need for sintering at high temperatures. The MoS2 ink has a very high resistance at a few printing passes due to lower coverage of the substrate therefore for this ink these measurements were not possible to be made. The main pigment composition of the paper coatings of the substrates was evaluated using FT-IR and EDX, these data plus the coating structure evaluated by SEM was related to the print quality.The best in test papers were used to print MoS2 electrodes. After the printing tests, another step for the optimization of the MoS2 ink properties shall be carried out in future studies for better print quality. We also evaluated the surface energy of the substrates through contact angle measurements to match the surface tension of the PEDOT:PSS ink and later the MoS2 ink. Although the pigmented coated printing substrate did not show better results than the commercial photo papers and PE foil in terms of line quality, it shows the lowest resistivity and sufficient results for low cost recyclable electronics, which do not require high conductivity. Nevertheless, the substrate was very thin and it could even be used in magazines as traditional lightweight coated papers (LWC) are used but with the additional of a printed electronic feature.
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| 4. |
- Zhang, Renyun, et al.
(författare)
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Cellulose-Based Fully Green Triboelectric Nanogenerators with Output Power Density of 300 W m−2
- 2020
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 32:38
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Tidskriftsartikel (refereegranskat)abstract
- Triboelectric nanogenerators (TENGs) have attracted increasing attention because of their excellent energy conversion efficiency, the diverse choice of materials, and their broad applications in energy harvesting devices and self-powered sensors. New materials have been explored, including green materials, but their performances have not yet reached the level of that for fluoropolymers. Here, a high-performance, fully green TENG (FG-TENG) using cellulose-based tribolayers is reported. It is shown that the FG-TENG has an output power density of above 300 W m−2, which is a new record for green-material-based TENGs. The high performance of the FG-TENG is due to the high positive charge density of the regenerated cellulose. The FG-TENG is stable after more than 30 000 cycles of operations in humidity of 30%–84%. This work demonstrates that high-performance TENGs can be made using natural green materials for a broad range of applications.
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| 5. |
- Zhang, Renyun, et al.
(författare)
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Energy Harvesting Using Wastepaper-Based Triboelectric Nanogenerators
- 2023
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Ingår i: Advanced Engineering Materials. - : Wiley. - 1438-1656 .- 1527-2648. ; 25:11
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Tidskriftsartikel (refereegranskat)abstract
- Inks and toners used for printing contain materials, such as polyester, with strong triboelectric properties to enhance the binding effects, making wastepaper, such as magazines and newspapers, good candidates for triboelectric materials. Herein, high-output power triboelectric nanogenerators (TENGs) that utilize wastepaper as triboelectric layers (wastepaper-based triboelectric nanogenerators (WP–TENGs)) are reported. Journal paper and office copy paper wastes are investigated. The results show that the maximum power densities of the WP–TENGs reach 43.5 W m−2, which is approximately 250 times the previously reported output of the TENG with a recycled triboelectric layer made from wastepaper. The maximum open circuit voltage (V OC) and short circuit current (I SC) are 774 V and 3.92 mA (784 mA m−2), respectively. These findings can be applied to extend the life cycle of printed papers for energy harvesting, and they can later be applied for materials recycling to enhance the sustainable development of our society.
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| 6. |
- Zhang, Renyun, et al.
(författare)
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Soap-film coating : High-speed deposition of multilayer nanofilms
- 2013
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Ingår i: Scientific Reports. - Nature Publishing Group : Springer Science and Business Media LLC. - 2045-2322. ; 3, s. Art. no. 1477-
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Tidskriftsartikel (refereegranskat)abstract
- The coating of thin films is applied in numerous fields and many methods are employed for the deposition of these films. Some coating techniques may deposit films at high speed; for example, ordinary printing paper is coated with micrometre-thick layers of clay at a speed of tens of meters per second. However, to coat nanometre thin films at high speed, vacuum techniques are typically required, which increases the complexity of the process. Here, we report a simple wet chemical method for the high-speed coating of films with thicknesses at the nanometre level. This soap-film coating technique is based on forcing a substrate through a soap film that contains nanomaterials. Molecules and nanomaterials can be deposited at a thickness ranging from less than a monolayer to several layers at speeds up to meters per second. We believe that the soap-film coating method is potentially important for industrial-scale nanotechnology.
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| 7. |
- Zhang, Renyun, et al.
(författare)
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Triboelectric nanogenerators with ultrahigh current density enhanced by hydrogen bonding between nylon and graphene oxide
- 2023
-
Ingår i: Nano Energy. - 2211-2855 .- 2211-3282. ; 115
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Tidskriftsartikel (refereegranskat)abstract
- The triboelectric properties of the tribolayers are essential factors affecting the current density of triboelectric nanogenerators (TENGs). To enhance the current density, composites have been developed to tune their triboelectric properties. Previous studies have reported enhanced TENG performance with composite materials, primarily based on their composition, while chemical interactions between the components have been less analyzed. In this study, we report a novel approach to improve the current density of a TENG by introducing dipole-dipole interactions between a nylon filter membrane and graphene oxide (GO) through hydrogen bonds. The Raman spectroscopy confirmed the occurrence of the interactions resulting from hydrogen bonding. The enhancing mechanisms of hydrogen bonds were further analyzed by Kelvin probe force microscope (KPFM) measurement, which demonstrated that hydrogen bonding could influence the surface potential of the coated GO, leading to increased output of the nylon/GO@NFM TENG (NGN-TENG). Our results show that an ultrahigh current density of 1757 mA·m−2 was obtained with a 2 × 2 cm2 NGN-TENG. Additionally, we demonstrated the feasibility of using the NGN-TENG as a motion sensor to sense finger motions. These findings suggest that the introduction of hydrogen bonds in TENG composites can provide a promising route for improving their performance.
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| 8. |
- Zhang, Renyun, et al.
(författare)
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Wastepaper-based Triboelectric Nanogenerators
- 2023
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Ingår i: Book of Abstracts EPNOE 2023. - : Graz University of Technology.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- nks and toners used for printing contain materials, such as polyester, with strong triboelectric properties to enhance the binding effects, making wastepaper, such as magazines and newspapers, good candidates for triboelectric materials. In this study, we report high- output power triboelectric nanogenerators (TENGs) that utilize wastepaper as triboelectric layers (wastepaper-based triboelectric nanogenerators (WP–TENGs)) [1]. Journal paper and office copy paper wastes are investigated. The results show that the maximum power densities of the WP–TENGs reach 43.5 W·m-2, which is approximately 250 times the previously reported output of the TENG with a recycled triboelectric layer made from wastepaper [2]. The maximum open circuit voltage (VOC) and short circuit current (ISC) are 774 V and 3.92 mA (784 mA m-2), respectively. These findings can be applied to extend the life cycle of printed papers for energy harvesting, and they can later be applied for materials recycling to enhance the sustainable development of our society.[1] Zhang, R., Hummelgård, M., Örtegren, J., Andersson, H., Olsen, M., Chen, W., Wang, P., Eivazi, A., Dahlström, C. & Norgren, M. Adv. Engin. Mater., in press, 2023; https://doi.org/10.1002/adem.202300107[2] Zhang, Z., Jie, Y., Zhu, J., Zhu, Z., Chen, H, Lu, Q., Zeng, Y., Cao, X., Wang, N. & Wang, Z. Nano Res. 15, 1109, 2022; https://doi.org/10.1007/s12274-021-3612-8
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| 9. |
- Andres, Britta, 1986-, et al.
(författare)
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Cellulose binders for electric double-layer capacitor electrodes : The influence of cellulose quality on electrical properties
- 2018
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Ingår i: Materials & design. - : Elsevier BV. - 0264-1275 .- 1873-4197. ; 141, s. 342-349
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose derivatives are widely used as binders and dispersing agents in different applications. Binders composed of cellulose are an environmentally friendly alternative to oil-based polymer binding agents. Previously, we reported the use of cellulose nanofibers (CNFs) as binders in electrodes for electric double-layer capacitors (EDLCs). In addition to good mechanical stability, we demonstrated that CNFs enhanced the electrical performance of the electrodes. However, cellulose fibers can cover a broad range of length scales, and the quality requirements from an electrode perspective have not been thoroughly investigated. To evaluate the influence of fiber quality on electrode properties, we tested seven samples with different fiber dimensions that are based on the same kraft pulp. To capture the length scale from fibers to nanofibrils, we evaluated the performance of the untreated kraft pulp, refined fibers, microfibrillated cellulose (MFC) and CNFs. Electrodes with kraft pulp or refined fibers showed the lowest electrical resistivity. The specific capacitances of all EDLCs were surprisingly similar, but slightly lower for the EDLC with CNFs. The same electrode sample with CNFs also showed a slightly higher equivalent series resistance (ESR), compared to those of the other EDLCs. Graphite dispersions with MFC showed the best dispersion stability.
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| 10. |
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| 11. |
- Costa, Carolina
(författare)
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Cellulose Dissolution and Amphiphilicity : Insights on the Emulsion Formation and Stabilization
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An amphiphilic polymer is expected to adsorb at the oil-water interface and be capable of stabilizing emulsions. Cellulose derivatives, cellulose nanoparticles and regenerated cellulose particles show an intrinsic amphiphilic character by self-assembling at oil-water interfaces and stabilizing emulsions without the aid of surfactants or any other co-stabilizers. In its polymeric form, the native cellulose chains could be expected to share similar emulsifying abilities. However, cellulose dissolution is the main issue when it comes to its direct application in emulsion technology and, therefore, there is a lack of knowledge when it comes to this type of approach on making emulsions. Cellulose does not dissolve in either oil or water, but it can be dissolved in water based-solvents at extreme pH's. In this thesis, the interfacial behaviour of cellulose was studied at oil-water interfaces by having cellulose dissolved in aqueous solutions of H3PO4 (very low pH) and NaOH/NaOH-urea and TBAH (very high pH). In its dissolved state, cellulose was seen to substantially decrease the interfacial tension (IFT) between the oil phase and the aqueous media, which was a consequence of the adsorption of cellulose at oil-water interfaces. The extent of the IFT reduction was shown to be dependent on the solvent quality. The optimal solvency conditions for cellulose were found for the alkaline solvent with an intermediate polarity (NaOH-urea), which is in line with the favourable conditions for adsorption of an amphiphilic polymer. However, in stabilizing oil-in-water emulsions (O/W), to achieve long-term stability and prevent oil separation from the emulsions, further reduction in cellulose's solvency was needed. This was achieved by a change in the pH of the emulsions that induced the regeneration of cellulose on the surface of the oil droplets (in-situ regeneration) in the form of a continuous film, which was revealed by cryogenic scanning electron microscopy (cryo-SEM). The topography of the droplets surface was found to be very different from what has been reported for cellulose Pickering emulsions. Upon in-situ regeneration, the rate of droplets coalescence was dramatically reduced and emulsions showed a remarkable stability against oil-separation. Finally, the combination of cellulose with lignin as an amphiphilic natural co-stabilizer was studied regarding their compatibility in solution. Lignin was found to improve cellulose dissolution in NaOH (aq.) and delay the gelation kinetics upon ageing or temperature increase in the solutions. Data suggests lignin as an amphiphilic additive able to weaken the hydrophobic interactions among cellulose molecules.
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| 12. |
- Costa, Carolina, et al.
(författare)
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Cellulose-stabilized oil-in-water emulsions : Structural features, microrheology, and stability
- 2021
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 252
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose-based oil-in-water (O/W) emulsions were studied by diffusing wave spectroscopy (DWS) regarding the effect of the cellulose concentration and mixing rate on the average droplet size, microrheological features and stability. Furthermore, the microstructure of these emulsions was imaged by cryo-scanning electron microscopy (cryo-SEM). The micrographs showed that cellulose was effectively adsorbed at the oil-water interface, resembling a film-like shell that protected the oil droplets from coalescing. The non-adsorbed cellulose that was observed in the continuous aqueous medium, contributed to the enhancement of the viscosity of the medium, leading to an improvement in the stability of the overall system. Generally, the higher the cellulose concentration and mixing rate, the smaller the emulsion droplets formed, and the higher was their stability. The combination of both techniques, DWS and cryo-SEM, revealed a very appealing and robust methodology for the characterization and design of novel emulsion-based formulations.
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| 13. |
- Costa, Carolina, et al.
(författare)
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Emulsion Formation and Stabilization by Biomolecules : The Leading Role of Cellulose.
- 2019
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Ingår i: Polymers. - : MDPI AG. - 2073-4360. ; 11:10
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Tidskriftsartikel (refereegranskat)abstract
- Emulsion stabilization by native cellulose has been mainly hampered because of its insolubility in water. Chemical modification is normally needed to obtain water-soluble cellulose derivatives. These modified celluloses have been widely used for a range of applications by the food, cosmetic, pharmaceutic, paint and construction industries. In most cases, the modified celluloses are used as rheology modifiers (thickeners) or as emulsifying agents. In the last decade, the structural features of cellulose have been revisited, with particular focus on its structural anisotropy (amphiphilicity) and the molecular interactions leading to its resistance to dissolution. The amphiphilic behavior of native cellulose is evidenced by its capacity to adsorb at the interface between oil and aqueous solvent solutions, thus being capable of stabilizing emulsions. In this overview, the fundamentals of emulsion formation and stabilization by biomolecules are briefly revisited before different aspects around the emerging role of cellulose as emulsion stabilizer are addressed in detail. Particular focus is given to systems stabilized by native cellulose, either molecularly-dissolved or not (Pickering-like effect).
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| 14. |
- Costa, Carolina, et al.
(författare)
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Interfacial activity and emulsion stabilization of dissolved cellulose
- 2019
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Ingår i: Journal of Molecular Liquids. - : Elsevier B.V.. - 0167-7322 .- 1873-3166. ; 292
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Tidskriftsartikel (refereegranskat)abstract
- Some aspects of the interfacial behavior of cellulose dissolved in an aqueous solvent were investigated. Cellulose was found to significantly decrease the interfacial tension (IFT) between paraffin oil and 85 wt% phosphoric acid aqueous solutions. This decrease was similar in magnitude to that displayed by non-ionic cellulose derivatives. Cellulose's interfacial activity indicated a significant amphiphilic character and that the interfacial activity of cellulose derivatives is not only related to the derivatization but inherent in the cellulose backbone. This finding suggests that cellulose would have the ability of stabilizing dispersions, like oil-in-water emulsions in a similar way as a large number of cellulose derivatives. In its molecularly dissolved state, cellulose proved to be able to stabilize emulsions of paraffin in the polar solvent on a short-term. However, long-term stability against drop-coalescence was possible to achieve by a slight change in the amphiphilicity of cellulose, effected by a slight increase in pH. These emulsions exhibited excellent stability against coalescence/oiling-off over a period of one year. Ageing of the cellulose solution before emulsification (resulting in molecular weight reduction) was found to favour the creation of smaller droplets.
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| 15. |
- Costa, Carolina, et al.
(författare)
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Lignin enhances cellulose dissolution in cold alkali
- 2021
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 274
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Tidskriftsartikel (refereegranskat)abstract
- Aqueous sodium hydroxide solutions are extensively used as solvents for lignin in kraft pulping. These are also appealing systems for cellulose dissolution due to their inexpensiveness, ease to recycle and low toxicity. Cellulose dissolution occurs in a narrow concentration region and at low temperatures. Dissolution is often incomplete but additives, such as zinc oxide or urea, have been found to significantly improve cellulose dissolution. In this work, lignin was explored as a possible beneficial additive for cellulose dissolution. Lignin was found to improve cellulose dissolution in cold alkali, extending the NaOH concentration range to lower values. The regenerated cellulose material from the NaOH-lignin solvents was found to have a lower crystallinity and crystallite size than the samples prepared in the neat NaOH and NaOH-urea solvents. Beneficial lignin-cellulose interactions in solution state appear to be preserved under coagulation and regeneration, reducing the tendency of crystallization of cellulose.
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| 16. |
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| 17. |
- Costa, Carolina, et al.
(författare)
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On the formation and stability of cellulose-based emulsions in alkaline systems : Effect of the solvent quality
- 2022
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 286
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Tidskriftsartikel (refereegranskat)abstract
- With amphiphilic properties, cellulose molecules are expected to adsorb at the O/W interface and be capable of stabilizing emulsions. The effect of solvent quality on the formation and stability of cellulose-based O/W emulsions was evaluated in different alkaline systems: NaOH, NaOH-urea and tetrabutylammonium hydroxide (TBAH). The optimal solvency conditions for cellulose adsorption at the O/W interface were found for the alkaline solvent with an intermediate polarity (NaOH-urea), which is in line with the favorable conditions for adsorption of an amphiphilic polymer. A very good solvency (in TBAH) and the interfacial activity of the cation lead to lack of stability because of low cellulose adsorption. However, to achieve long-term stability and prevent oil separation in NaOH-urea systems, further reduction in cellulose's solvency was needed, which was achieved by a change in the pH of the emulsions, inducing the regeneration of cellulose at the surface of the oil droplets (in-situ regeneration).
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| 18. |
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| 19. |
- Dahlström, Christina, 1977-, et al.
(författare)
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Ion conductivity through TEMPO-mediated oxidated and periodate oxidated cellulose membranes
- 2020
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Ingår i: Carbohydrate Polymers. - : ELSEVIER SCI LTD. - 0144-8617 .- 1879-1344. ; 233
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose in different forms is increasingly used due to sustainability aspects. Even though cellulose itself is an isolating material, it might affect ion transport in electronic applications. This effect is important to understand for instance in the design of cellulose-based supercapacitors. To test the ion conductivity through membranes made from cellulose nanofibril (CNF) materials, different electrolytes chosen with respect to the Hofmeister series were studied. The CNF samples were oxidised to three different surface charge levels via 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), and a second batch was further cross-linked by periodate oxidation to increase wet strength and stability. The outcome showed that the CNF pre-treatment and choice of electrolyte are both crucial to the ion conductivity through the membranes. Significant specific ion effects were observed for the TEMPO-oxidised CNF. Periodate oxidated CNF showed low ion conductivity for all electrolytes tested due to an inhibited swelling caused by the crosslinking reaction.
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| 20. |
- Dahlström, Christina, 1977-, et al.
(författare)
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Regenerated cellulose properties tailored for optimized triboelectric output and the effect of counter-tribolayers
- 2024
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Ingår i: Cellulose. - : Springer Nature. - 0969-0239 .- 1572-882X. ; 31:4, s. 2047-2061
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose has shown great potential in the development of green triboelectric nanogenerators. Particularly, regenerated cellulose (R-cellulose) has shown remarkably high output power density but the structural features and key parameters that explain such superior performance remain unexplored. In this work, wood cellulose fibers were dissolved in a LiOH(aq)-based solvent to produce a series of R-cellulose films. Regeneration in different alcohols (from methanol to n-pentanol) was performed and the films’ structural features and triboelectric performance were assessed. Nonsolvents of increased hydrophobicity led to R-cellulose films with a more pronounced (1–10) diffraction peak. An open-circuit voltage (VOC) of up to ca. 260 V and a short-circuit current (ISC) of up to ca. 150 µA were measured for R-cellulose against polytetrafluoroethylene (as negative counter-layer). However, R-cellulose showed an increased VOC of 175% (from 88.1 V) against polydimethylsiloxane when increasing the alcohol hydrocarbon chain length from methanol to n-pentanol. The corresponding ISC and output power also increased by 76% (from 89.9 µA) and by 382% (from 8.8 W m–2), respectively. The higher R-cellulose hydrophilicity, combined with soft counter-tribolayer that follow the surface structures increasing the effective contact area, are the leading reasons for a superior triboelectric performance.
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| 21. |
- Dahlström, Christina, 1977-, et al.
(författare)
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Triboelectric Performance Of Regenerated Cellulose
- 2023
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Ingår i: Book of Abstracts EPNOE 2023. - : Graz University of Technology. ; , s. 116-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Cellulose has shown great potential in the development of green triboelectric nanogenerators (TENG) [1]. Particularly, regenerated cellulose (R-cellulose) has shown remarkably high output power density but the structural features and key parameters that explain such superior performance remain unexplored. In this work, wood cellulose fibers were dissolved in a LiOH(aq)-based solvent to produce a series of R-cellulose films. Regeneration in different alcohols (from methanol to n-pentanol) was performed and the films’ structural features and triboelectric performance were assessed. Nonsolvents of increased hydrophobicity led to R-cellulose films with higher hydrophilic character; the films showed a (1- 10) diffraction peak of larger amplitude and higher apparent crystallinity. An open-circuit voltage (VOC) of up to ca. 260 V and a short-circuit current (ISC) of up to ca. 150 μA were measured for R-cellulose against polytetrafluoroethylene (as negative counter-layer). However, R-cellulose showed an increased VOC of 175% (from 88.1 V) against polydimethylsiloxane from methanol to n-pentanol. The corresponding ISC and output power also increased by 76% (from 89.9 μA) and by 382% (from 8.8 W m–2), respectively. The higher R-cellulose hydrophilicity, combined with soft counter-layer that follow the surface structures increasing the effective contact area, are the leading reasons for a superior triboelectric performance.[1] Zhang, R., Dahlström, C., Zou, H., Jonzon, J., Hummelgård, M., Örtegren, J., Blomquist, N., Yang, Y., Andersson, H., Olsen, M., Norgren, M., Olin, H. & Wang, Z.L. Adv. Mater. 32, 2002824, 2020; https://doi.org/10.1002/adma.202002824
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| 22. |
- Eivazi, Alireza, et al.
(författare)
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On the development of all-cellulose capsules by vesicle-templated layer-by-layer assembly
- 2021
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Ingår i: Polymers. - : MDPI AG. - 2073-4360. ; 13:4
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Tidskriftsartikel (refereegranskat)abstract
- Polymeric multilayer capsules formed by the layer-by-layer (LbL) technique are interesting candidates for the purposes of storage, encapsulation, and release of drugs and biomolecules for pharmaceutical and biomedical applications. In the current study, cellulose-based core-shell particles were developed via the LbL technique alternating two cellulose derivatives, anionic carboxymethyl-cellulose (CMC), and cationic quaternized hydroxyethylcellulose ethoxylate (QHECE), onto a cationic vesicular template made of didodecyldimethylammonium bromide (DDAB). The obtained capsules were characterized by dynamic light scattering (DLS), ζ potential measurements, and high-resolution scanning electron microscopy (HR-SEM). DLS measurements reveal that the size of the particles can be tuned from a hundred nanometers with a low polydispersity index (deposition of 2 layers) up to micrometer scale (deposition of 6 layers). Upon the deposition of each cellulose derivative, the particle charge is reversed, and pH is observed to considerably affect the process thus demonstrating the electrostatic driving force for LbL deposition. The HR-SEM characterization suggests that the shape of the core-shell particles formed is reminiscent of the spherical vesicle template. The development of biobased nano-and micro-containers by the alternating deposition of oppositely charged cellulose derivatives onto a vesicle template offers several advantages, such as simplicity, reproducibility, biocompatibility, low-cost, mild reaction conditions, and high controllability over particle size and composition of the shell.
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| 23. |
- Eivazihollagh, Alireza, et al.
(författare)
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Controlled Synthesis of Cu and Cu2O NPs and Incorporation of Octahedral Cu2O NPs in Cellulose II Films
- 2018
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Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 8:4
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Tidskriftsartikel (refereegranskat)abstract
- In this study, Cu and Cu2O nanoparticles (NPs) were synthesized through chemical reduction of soluble copper-chelating ligand complexes using formaldehyde as a reducing agent. The influence of various chelating ligands, such as ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and a surface-active derivative of DTPA (C12-DTPA), as well as surfactants (i.e., hexadecyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium chloride (DoTAC), sodium dodecyl sulfate (SDS), and dimethyldodecylamine-N-oxide (DDAO)), on morphology and the composition of produced NPs was investigated. In the absence of surfactants, spherical copper particles with polycrystalline structure could be obtained. X-ray diffraction (XRD) analysis revealed that, in the presence of EDTA, the synthesized NPs are mainly composed of Cu with a crystallite size on the order of 35 nm, while with DTPA and C12-DTPA, Cu2O is also present in the NPs as a minority phase. The addition of ionic surfactants to the copper–EDTA complex solution before reduction resulted in smaller spherical particles, mainly composed of Cu. However, when DDAO was added, pure Cu2O nano-octahedrons were formed, as verified by high-resolution scanning electron microscopy (HR-SEM) and XRD. Furthermore, a hybrid material could be successfully prepared by mixing the octahedral Cu2O NPs with cellulose dissolved in a LiOH/urea solvent system, followed by spin-coating on silica wafers. It is expected that this simple and scalable route to prepare hybrid materials could be applied to a variety of possible applications.
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| 24. |
- Eivazihollagh, Alireza, et al.
(författare)
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Electrochemical recovery of copper complexed by DTPA and C12-DTPA from aqueous solution using a membrane cell
- 2018
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Ingår i: Journal of chemical technology and biotechnology (1986). - : Wiley. - 0268-2575 .- 1097-4660. ; 93:5, s. 1421-1431
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUNDThe electrochemical recovery of copper from DTPA and C12-DTPA (a surface-active derivative of DTPA) complex solutions was investigated in a membrane flow cell. Electrolysis time, solution flow rate, applied current density, and solution pH were evaluated.RESULTSThe chelating surfactant C12-DTPA can promote the kinetics of copper electrodeposition more than DTPA depending on the experimental conditions. At a current density of 30 A m–2, a solution flow rate of 0.6 L min–1, and pH 10 after 180 min treatment, the copper recovery and current efficiency were 50% and 43.3%, respectively, in the Cu(II)-DTPA system and about 65% and 53.6%, respectively, in the Cu(II)-C12-DTPA system. The differences in the amount of recovery could be explained in terms of differences in the diffusion of copper complexes with DTPA and C12-DTPA to the cathode, as well as their solution behavior and pH-dependent conditional stability constants (log10 K’CuDTPA3-).CONCLUSIONElectrochemical methods could be effectively combined with foam flotation for the chelating surfactant C12-DTPA, to recover copper and C12-DTPA. This makes the overall treatment more sustainable, and can be helpful in complying with the increasingly stringent environmental regulations
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| 25. |
- Eivazihollagh, Alireza
(författare)
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Metal-Chelate Complexes in Alkaline Solution : On Recovery Techniques and Cellulose-based Hybrid Material Synthesis
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- For decades, aminopolycarboxylate chelating agents have been extensively used in various industrial applications. The ability of chelating agents to form stable metal-chelate complexes is the main reason for using them to manage metal ions within water-based industrial processes. Considerable quantities of industrial effluent containing chelating agents and heavy metals are produced and often discharged into the environment. The toxicity of heavy metals and the non-biodegradability of the chelating agents, as well as their accumulation in the environment, has become cause for concern. The main purpose of this thesis was to evaluate and develop processes for recovery of chelated metal complexes from aqueous solution. In this regard, the membrane electrolysis technique was evaluated for recovery of copper and aminopolycarboxylic chelating ligands such as ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA), and a surface-active derivative of DTPA, 2-dodecyldiethylenetriaminepentaacetic acid (C12-DTPA) from aqueous solution. By using this method, it was possible to simultaneously recover the chelating ligand for further reuse and collect the metals by electrodeposition, making the process more cost-effective and hindering the discharge of copper ions and chelating ligands as pollutants into the environment. In addition, the ion flotation technique with the chelating surfactant C12-DTPA could be employed to separate metal ions, especially from their dilute solutions, and concentrate them in a foam phase. This is because C12-DTPA has a purpose-built functionality; besides forming strong coordination complexes with metal ions, it is also surface-active and will readily adsorb at air-water interfaces. In this study, C12-DTPA was effectively used in combination with foaming agents for the removal of toxic metal ions such as Cd2+, Zn2+, and Sr2+ from aqueous solution using ion flotation. From an economical perspective, this method could be combined with the membrane electrolysis technique to recover metal and regenerate chelating surfactant so that it can be reused.The present work also shows the synthesis of metal and metal oxide(s) nanoparticles (NPs) in alkaline aqueous solution containing chelated metal ions, in order to fabricate metal NPs–cellulose hybrid materials. Cellulose is the most abundant renewable material, with good mechanical performance and chemical resistivity in a wide range of solvents, which makes it a promising material to support metal NPs. In this respect, we developed a rapid and inexpensive one-pot synthesis of spherical copper NPs in a cellulose matrix. The hybrid material displayed antibacterial properties for both the gram-negative and gram-positive bacteria. The synthesis was further developed by studying the influence of various chelating ligands and surfactants on the NPs’ morphology and chemical composition. According to the results, DDAO, a zwitterionic surfactant, was found to mediate the formation of pure octahedral Cu2O NPs. In addition, a hybrid material film composed of regenerated cellulose and synthesized Cu2O nano-octahedrons was fabricated by spin-coating.
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| 26. |
- Eivazihollagh, Alireza, et al.
(författare)
-
On chelating surfactants : Molecular perspectives and application prospects
- 2019
-
Ingår i: Journal of Molecular Liquids. - : Elsevier BV. - 0167-7322 .- 1873-3166. ; 278, s. 688-705
-
Tidskriftsartikel (refereegranskat)abstract
- Chelating agents, molecules that very strongly coordinates certain metal ions, are used industrially as well as in consumer products to minimize disturbances and increase performance of reactions and applications. The widely used sequestering agents, nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) belong to this branch of readily water-soluble compounds. When these chemical structures also have hydrophobic parts, they are prone to adsorb at air-water interfaces and to self-assemble. Such bifunctional molecules can be called chelating surfactants and will have more extended utilization prospects than common chelating agents or ordinary ionic surfactants. The present review attempts to highlight the fundamental behavior of chelating surfactants in solution and at interfaces, and their very specific interactions with metal ions. Methods to recover chelating surfactants from metal chelates are also described. Moreover, utilization of chelating surfactants in applications for metal removal in environmental engineering and mineral processing, as well as for metal control in the fields of biology, chemistry and physics, is exemplified and discussed.
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| 27. |
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| 28. |
- Eivazihollagh, Alireza, et al.
(författare)
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Removal of Cd2+, Zn2+, and Sr2+ by Ion Flotation, Using a Surface-Active Derivative of DTPA (C12-DTPA)
- 2017
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 56:38, s. 10605-10614
-
Tidskriftsartikel (refereegranskat)abstract
- Ion flotation was studied for the removal of cadmium, zinc, and strontium ions from aqueous solutions at pH 5–9 in a customized flotation cell, using an aminopolycarboxylic chelating surfactant, 2-dodecyldiethylenetriamine pentaacetic acid (C12-DTPA) in combination with two foaming agents: dodecyltrimethylammonium chloride (DoTAC) and dimethyldodecylamine-N-oxide (DDAO). The results from experiments showed that both Zn2+ and Cd2+ could be removed via ion flotation to 100% at pH 5, and Sr2+ could be removed via ion flotation to 60%–70% at pH 7–9. The removal of metal ions from the flotation cell was seen to vary with pH, but this was not exclusively related to the magnitudes of the formed metal ion-chelating surfactant conditional stability constants. The removal was also dependent on the foam properties of the samples that were found to vary over the investigated pH interval. The outcome of the investigation points to the chelating surfactant C12-DTPA having excellent chelating properties for all of the studied ions above pH 7. In combination with correctly chosen foaming agents, the optimized surfactant system could be expected to provide very efficient remediation of waters polluted with metal ions via ion flotation.
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| 29. |
- Eivazihollagh, Alireza, et al.
(författare)
-
Vesicle-templated all-cellulose nanocapsules
- 2019
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Konferensbidrag (refereegranskat)abstract
- Polymeric multilayers capsules constructed using the layer-by-layer (LbL) technique are interesting candidates for the purposes of storage, encapsulation and release in a wide range of biomedical applications. In the current study, cellulose-based nanocapsules were produced via the LbL technique. In this procedure, alternating deposition of the two biocompatible polymers anionic cellulose, carboxymethylcellulose (CMC), and cationic cellulose, quaternized hydroxyethylcellulose ethoxylate (QHECE), on a cationic vesicular template made of didodecyldimethylammonium bromide (DDAB), was performed. The obtained nanocapsules, were characterized by dynamic light scattering (DLS), ⇣ potential measurements, and field-emission scanning electron microscopy (FE-SEM). DLS measurements revealed that the size of the spheres is about hundreds of nanometer with polydispersity index (PDI) values between 0.2 and 0.3, indicating a relatively homogeneous size distribution. In addition, FESEM characterization also indicated the shape and size of obtained material. The surface charge analysis of the nanocapsules by ⇣ potential measurements indicated the presence of electrostatically stabilized nanoparticles. The values of diameter, PDI and surface charge for cationic vesicles coated by CMC were 204 nm, 0.26 and –38 mV, respectively. After deposition of QHECE, the diameter, PDI, and surface charge were about 265 nm, 0.36 and +32.5 mV, respectively. Figure 1 shows FE-SEM images of cellulose nanoparticles fabricated via LbL deposition of polyelectrolyte layers. As seen in the microscopy images, the shape of the core-shell particles are not fully spherical which could be due to drying e↵ects of the sample before FE-SEM characterization. The construction of cellulose nanocontainers by using an alternating deposition of oppositely charged biobased polyelectrolytes on vesicles o↵ers several advantages such as simplicity, reproducibility, biocompatibility, low-cost, mild reaction conditions, and high controllability over the thickness and composition of the shell.
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| 30. |
- El Miri, Nassima, et al.
(författare)
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A comprehensive investigation on modified cellulose nanocrystals and their films properties
- 2022
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Ingår i: International Journal of Biological Macromolecules. - : Elsevier B.V.. - 0141-8130 .- 1879-0003. ; 219, s. 998-1008
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, we aimed to tune cellulose nanocrystals (CNCs) properties by introducing different functional groups (aldehyde, carboxyl, silane, and ammonium groups) on the surface through different chemical modifications. These functional groups were obtained by combining: the periodate oxidation with TEMPO-oxidation, aminosylation or cationization. CNCs produced and their films were characterized to elucidate their performances. The results showed that the properties of obtained CNCs varied depending on the grafted functionalities on the surface. The results reveal that after each modification a colloidal stability is preserved. Interestingly, Periodate oxidation of cellulose nanocrystals results in film components that interact through intra- and intermolecular hemiacetals and lead to films with a tensile strength of 116 MPa compared to the pristine CNCs, in contrast the subsequent modifications led to lower tensile strength. Of note, remarkable thermal stability has been achieved after modifications reaching a maximum of 280 °C. The oxygen barrier properties of the films after modifications varied between 0.48 and 0.54 cm3μm/(m2d*kPa) at 50 % RH.
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| 31. |
- El Miri, Nassima, et al.
(författare)
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Cellulose nanocrystals : a new route towards strong nature-based and barrier materials
- 2019
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Ingår i: EPNOE2019 Book of Abstracts. ; , s. 97-
-
Konferensbidrag (refereegranskat)abstract
- An increasing consciousness toward the reduction of the environmental impact producedby plastic waste, has driven research and industry to focus on using biodegradable materials. Among those biodegradable materials, polysaccharides are regarded to have great potential in packaging applications, because of their outstanding performance with biocompatibility, biodegradability, and good processability. Naturally, most of the polysaccharides do not exhibit desired barrier properties, due to their hydrophilic nature, which hinder their application in packaging field. The incorporation of reinforcing structures such as cellulosenanocrystals (CNCs) in these polysaccharides is promising approach to produce new materials for food packaging application with specific properties and high performances. CNCs have been mostly used as reinforcing phase in matrices for a variety of materials, and thus given to their outstanding properties such as exceptional mechanical strength, biocompatibility, broadchemical modification, and large surface area. The aim of this study is the development of biodegradable films based on polysaccharides and CNCs from different ressources using agreen method such as the evaporation casting method and focusing on the final produced material properties related to food packaging applications (mechanical properties, thermal properties, antibacterial properties, optical transparency and resistance to water vapor and oxygen transmission).
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| 32. |
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| 33. |
- Fiskari, Juha, et al.
(författare)
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Deep Eutectic Solvent Treatment to Low-Energy TMP to Produce Fibers for Papermaking
- 2018
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Ingår i: IMPC 2018. - Trondheim, Norway.
-
Konferensbidrag (refereegranskat)abstract
- The aim of this research was to gain a better understanding on whether a novel process based on low-energy thermo-mechanical pulp (TMP) process followed by a chemical treatment with deep eutectic solvents (DESs) could produce fibers suitable for papermaking. In full scale production, these fibers could be produced at a much lower capital and operational costs, especially when utilizing existing TMP plants which are under the threat to be shut down or have already been shut down due to a decreasing demand for newsprint and other wood-containing papers.The efficiency of several DES treatments under various temperatures and times were evaluated by carrying out experiments in standard Teflon-lined autoclaves. A few tests were also performed in a unique nonstandard flow extractor. Pulp samples were characterized for their cellulose, hemicellulose and lignin contents. Moreover, tensile index was measured both before and after pulp refining. Depending on the solvent, the response of mechanical pulp varied, especially in terms of hemicellulose dissolution. Lactic acid, oxalic acid and urea, all in combination with choline chloride ([Ch]Cl) as the hydrogen bond acceptor, dissolved about 50% of the lignin of the low-energy TMP fibers under the tested conditions. The mixture of malic acid and [Ch]Cl was less effective in lignin dissolution. The mixture of urea and [Ch]Cl exhibited only a minor loss in hemicellulose content, when compared to the other tested DESs. Although 50% of the lignin was dissolved with minor loss in hemicellulose no improvement in tensile strength was observed, as it was rather the opposite. Another benefit with the mixture of urea and [Ch]Cl was that this DES did not appear to be corrosive to stainless steel. All other tested DESs—which were also quite acidic—were observed to be corrosive. Moreover, this DES-related corrosion was found to intensify at elevated temperatures.When chips were used as starting material with otherwise the same conditions almost no lignin was dissolved. This suggests that low-energy mechanical pulp is likely to be a good starting material for extracting lignin using DESs.
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| 34. |
- Forsberg, Viviane, et al.
(författare)
-
Electronic performance of printed PEDOT:PSS lines correlated to the physical and chemical properties of coated inkjet papers
- 2019
-
Ingår i: RSC Advances. - : ROYAL SOC CHEMISTRY. - 2046-2069. ; 9:41, s. 23925-23938
-
Tidskriftsartikel (refereegranskat)abstract
- PEDOT:PSS organic printed electronics chemical interactions with the ink-receiving layer (IRL) of monopolar inkjet paper substrates and coating color composition were evaluated through Raman spectroscopy mapping in Z (depth) and (XY) direction, Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray spectroscopy (EDS). Other evaluated properties of the IRLs were pore size distribution (PSD), surface roughness, ink de-wetting, surface energy and the impact of such characteristics on the electronics performance of the printed layers. Resin-coated inkjet papers were compared to a multilayer coated paper substrate that also contained an IRL but did not contain the plastic polyethylene (PE) resin layer. This substrate showed better electronic performance (i.e., lower sheet resistance), which we attributed to the inert coating composition, higher surface roughness and higher polarity of the surface which influenced the de-wetting of the ink. The novelty is that this substrate was rougher and with somewhat lower printing quality but with better electronic performance and the advantage of not having PE in their composite structure, which favors recycling.
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| 35. |
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| 36. |
- Forsberg, Viviane, 1981-, et al.
(författare)
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Liquid Exfoliation of Layered Materials in Water for Inkjet Printing
- 2016
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Ingår i: Printing for Fabrication 2016. - USA : Curran Associates, Inc.. - 9780892083220 - 9780892083237 - 9780892083213 ; 60:4, s. 1-7
-
Konferensbidrag (refereegranskat)abstract
- MoS2 is a layered material which is abundant and non-toxic and has been increasingly studied during the last few years as a semiconducting alternative to graphene. While most studies have been performed on single MoS2 nanosheets, for example to demonstrate high-performance electronic transistors, more work is needed to explore the use of MoS2 in printed electronics. The importance of using MoS2 as a printed electronic material could be understood by considering the several orders higher electron mobility in MoS2, even in several nanometer thick layers, compared to the organic and other materials used today. In the few studies performed so far on printing MoS2, the developed dispersions used mainly organic solvents that might be detrimental for the environment. Here, we show an environmentally friendly liquid-based exfoliation method in water where the solution was stabilized by sodium dodecyl sulfate (SDS) surfactant. The dispersions consisted of very thin MoS2 nanosheets with average lateral size of about 150 nm, surface tension of 28 mN m-1 and a shelf life of a year. Although both the concentration and viscosity was less than optimal, we were able to inkjet print the MoS2 solution on paper and on PET films, using multiple printing passes. By tuning the concentration/viscosity, this approach might lead to an environmentally friendly MoS2 ink suitable for printed electronics.
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| 37. |
- Forsberg, Viviane, 1981-
(författare)
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Liquid-Phase Exfoliation of Two-Dimensional Materials : Applications, deposition methods and printed electronics on paper
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- After the unprecedented success of graphene research, other materials that can also be exfoliated into thin layers, like Transition metal dichalcogenides (TMDs) such as molybdenum disulfide (MoS2), have also become the subjects of extensive studies. As one of the most promising methods for large scale production of such materials, liquid-phase exfoliation (LPE) has also been the subject of extensive research and is maturing as a field to the point that devices using additive manufacturing and printed nanosheets are often reported. The stability of the nanosheets in environmentally friendly solvents, particularly in water, with or without stabilizers, is still a focus of great interest for sustainable and commercial production. In this thesis, different methods of LPE in water with and without stabilizers are investigated and discussed. Stabilizers such as surfactant sodium dodecyl sulfate (SDS) and modified cellulose2-hydroxyethyl cellulose (HEC), were employed. Because waterdoes not have surface energy parameters that match those of2D materials, the dispersions in water do not usually have a high yield. Therefore, to circumvent the use of organic solvents that are known to be able to successfully exfoliate and stabilize nanosheets of two-dimensional materials, this thesis focuses on water as the solution-process medium for exfoliation and the assisting stabilizers used to keep the exfoliated nanomaterials in dispersion with a long half-time. Surfactant-assisted dispersions are discussed together with test-printing resultsusing inkjet to deposit the material. Process parameters for the LPE method using HEC as a stabilizer are presented together with thin nanosheets characterized by Raman spectroscopy. Dispersions using HEC presented the longest half-time among the studied methods, higher than previously reported values for methods using mixed low-boiling-point solvents. Devices using exfoliated nanosheets have been fabricated and presented in the present study. The photoconductivity of MoS2 using a device fabricated with LPE MoS2 nanosheets and the cathodoluminescence of LPE MoS2 are discussed. Although fabricated with mechanically exfoliated nanosheets and not LPE ones, another photodetector fabricated with one of the MoS2 grades used in this thesis is presented to highlight the excellent photoresponse of this material. A method of producing thin nanosheets with-out stabilizers by pre-processing the MoS2 grades withs and papers is introduced. With this method, nanosheets with a lateral size of around 200nm and a concentration around 0.14 g L−1 - that is half the concentration at the same processing conditions in solvent n-methyl pyrrolidone (NMP) - are discussed. Inkjet printing as a deposition method is discussed together with the requirements for the 2D inks. Printed organic electronics using the conductive polymer PEDOT:PSS are compared to those using commercially-available graphene ink, with a focus on printing on paper substrates. In order to bring the thesis into perspective from materials to device fabrication, I study the suitability of inkjet paper substrates for printed electronics, by extensively characterizing the chemical and physical properties of their ink-receiving layers (IRLs) and their impact on the electronic properties of the conductive printed lines.
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| 38. |
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| 39. |
- From, Malin, et al.
(författare)
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Tuning the properties of regenerated cellulose : Effects of polarity and water solubility of the coagulation medium
- 2020
-
Ingår i: Carbohydrate Polymers. - : Elsevier Ltd. - 0144-8617 .- 1879-1344. ; 236
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, the effect of different alcohols and esters as a coagulation medium in the regeneration of cellulose dissolved in an aqueous LiOH-urea-based solvent was thoroughly investigated using various methods such as solid state NMR, X-ray diffraction, water contact angle, oxygen gas permeability, mechanical testing, and scanning electron microscopy. It was observed that several material properties of the regenerated cellulose films follow trends that correlate to the degree of cellulose II crystallinity, which is determined to be set by the miscibility of the coagulant medium (nonsolvent) and the aqueous alkali cellulose solvent rather than the nonsolvents’ polarity. This article provides an insight, thus creating a possibility to carefully tune and control the cellulose material properties when tailor-made for different applications.
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| 40. |
- Gericke, Martin, et al.
(författare)
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The European Polysaccharide Network of Excellence (EPNOE) research roadmap 2040: Advanced strategies for exploiting the vast potential of polysaccharides as renewable bioresources
- 2024
-
Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 326
-
Tidskriftsartikel (refereegranskat)abstract
- Polysaccharides are among the most abundant bioresources on earth and consequently need to play a pivotal role when addressing existential scientific challenges like climate change and the shift from fossil-based to sustainable biobased materials. The Research Roadmap 2040 of the European Polysaccharide Network of Excellence (EPNOE) provides an expert's view on how future research and development strategies need to evolve to fully exploit the vast potential of polysaccharides as renewable bioresources. It is addressed to academic researchers, companies, as well as policymakers and covers five strategic areas that are of great importance in the context of polysaccharide related research: (I) Materials & Engineering, (II) Food & Nutrition, (III) Biomedical Applications, (IV) Chemistry, Biology & Physics, and (V) Skills & Education. Each section summarizes the state of research, identifies challenges that are currently faced, project achievements and developments that are expected in the upcoming 20 years, and finally provides outlines on how future research activities need to evolve.
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| 41. |
- Ibrahem, Ismail, et al.
(författare)
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Copper Nanoparticles on Controlled Pore Glass and TEMPO for the Aerobic Oxidation of Alcohols
- 2018
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Ingår i: ChemNanoMat. - : Wiley. - 2199-692X. ; 4:1, s. 71-75
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Tidskriftsartikel (refereegranskat)abstract
- Herein, we report on the facile synthesis of a heterogeneous copper nanocatalyst and its combination with 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) for the aerobic oxidation of alcohols to their corresponding carbonyl compounds. This low cost copper nanocatalyst was found to exhibit excellent recyclability, making it a highly attractive catalytic system from an economical and environmental point of view. Extensive characterization of the catalyst by a number of techniques revealed that it was comprised of well-dispersed Cu(I/II) nanoparticles with an average size of around 6nm.
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| 42. |
- Johansson, Erik, et al.
(författare)
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Adsorption Behavior and Adhesive Properties of Biopolyelectrolyte Multilayers formed from Cationic and Anionic Starch
- 2009
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 10:7, s. 1768-1776
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Tidskriftsartikel (refereegranskat)abstract
- Cationic starch (D.S. 0.065) and anionic starch (D.S. 0.037) were used to form biopolyelectrolyte multilayers. The influence of the solution concentration of NaCl on the adsorption of starch onto silicon oxide substrates and on the formation of multilayers was investigated using stagnation point adsorption reflectometry (SPAR) and quartz crystal microbalance with dissipation (QCM-D). The wet adhesive properties of the starch multilayers were examined by measuring pull-off forces with the AFM colloidal probe technique. It was shown that polyelectrolyte multilayers (PEM) can be successfully constructed from cationic starch and anionic starch at electrolyte concentrations of 1 mM NaCl and 10 mM NaCl. The water content of the PEMs was approximately 80% at both electrolyte concentrations. However, the thickness of the PEMs formed at 10 mM NaCl was approximately twice the thickness formed at I mM NaCl. The viscoelastic properties of the starch PEMs, modeled as Voigt elements, were dependent on the polyelectrolyte that was adsorbed in the outermost layer. The PEMs appeared to be more rigid when capped by anionic starch than when capped by cationic starch. The wet adhesive pull-off forces increased with layer number and were also dependent oil the polyelectrolyte adsorbed in the outermost layer. Thus, starch PEM treatment has a large potential for increasing the adhesive interaction between solid substrates to levels higher than can be reached by a single layer of cationic starch.
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| 43. |
- Karlsson, P, et al.
(författare)
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Low-Density Cellulose-Based Foams: Preparation, Characterization and Biodegradation
- 2023
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Ingår i: Book of Abstracts EPNOE 2023. - : Graz University of Technology. ; , s. 345-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The demands for alternatives to fossil-based materials for the packaging and building sector is rapidly increasing as new regulations and laws are set. The usage of such materials in low- density applications is increasingly questioned since only a small amount is recycled and a large part ends up in the environment where it has a very long decomposition time and contributes to the emergence of microplastics in our marine eco systems. Alternatives to fossil- based low-density materials has been demonstrated using e.g., starch [1] and cellulose [2] as raw materials. However, challenges remain regarding the process parameters and properties such as strength and water integrity. To fulfil these properties requested by the specification owners, understanding is needed regarding which tools that are available for incorporating wet-integrity and hydrophobicity without causing the wet foam to collapse during the foaming or drying process. It is also of highest importance to have an early understanding of how such materials can be recycled and/or bio-degraded to fit a circular economy. In this study two different cross-linkers and two different types of hydrophobisers are used to obtain a wet stable and a water repelling low-density material. The wet foams are characterized by measuring the foamability and foam stability and the dry foams are characterized in terms of structure, porosity and degradability. Two demonstrators have been produced based on the most promising material composition and the up-scaling processes of the developed foaming technology to both batch-wise and continuous fabrication of composite foams is underway. Finally, a biodegradation study was conducted and evaluated.[1] S. Chaireh, P. Ngasatool, and K. Kaewtatip, “Novel composite foam made from starch and water hyacinth with beeswax coating for food packaging applications,” Int. J. Biol. Macromol., vol. 165, pp. 1382–1391, 2020[2] C. Qin, M. Yao, Y. Liu, Y. Yang, Y. Zong, and H. Zhao, “MFC/NFC-based foam/aerogel for production of porous materials: Preparation, properties and applications,” Materials (Basel)., vol. 13, no. 23, pp. 1–21, 2020
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| 44. |
- Lindman, Björn, et al.
(författare)
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Hydrophobic interactions control the self-assembly of DNA and cellulose
- 2021
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Ingår i: Quarterly reviews of biophysics (Print). - 0033-5835 .- 1469-8994. ; 54
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Tidskriftsartikel (refereegranskat)abstract
- Desoxyribosenucleic acid, DNA, and cellulose molecules self-assemble in aqueous systems. This aggregation is the basis of the important functions of these biological macromolecules. Both DNA and cellulose have significant polar and nonpolar parts and there is a delicate balance between hydrophilic and hydrophobic interactions. The hydrophilic interactions related to net charges have been thoroughly studied and are well understood. On the other hand, the detailed roles of hydrogen bonding and hydrophobic interactions have remained controversial. It is found that the contributions of hydrophobic interactions in driving important processes, like the double-helix formation of DNA and the aqueous dissolution of cellulose, are dominating whereas the net contribution from hydrogen bonding is small. In reviewing the roles of different interactions for DNA and cellulose it is useful to compare with the self-assembly features of surfactants, the simplest case of amphiphilic molecules. Pertinent information on the amphiphilic character of cellulose and DNA can be obtained from the association with surfactants, as well as on modifying the hydrophobic interactions by additives.
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| 45. |
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| 46. |
- Lindman, Björn, et al.
(författare)
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The relevance of structural features of cellulose and its interactions to dissolution, regeneration, gelation and plasticization phenomena
- 2017
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - 1463-9076 .- 1463-9084. ; 19:35, s. 23704-23718
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose is the most abundant polymer and a very important renewable resource. Since cellulose cannot be shaped by melting, a major route for its use for novel materials, new chemical compounds and renewable energy must go via the solution state. Investigations during several decades have led to the identification of several solvents of notably different character. The mechanisms of dissolution in terms of intermolecular interactions have been discussed from early work but, even on fundamental aspects, conflicting and opposite views appear. In view of this, strategies for developing new solvent systems for various applications have remained obscure. There is for example a strong need for using forest products for higher value materials and for environmental and cost reasons to use water-based solvents. Several new water-based solvents have been developed recently but there is no consensus regarding the underlying mechanisms. Here we wish to address the most important mechanisms described in the literature and confront them with experimental observations. A broadened view is helpful for improving the current picture and thus cellulose derivatives and phenomena such as fiber dissolution, swelling, regeneration, plasticization and dispersion are considered. In addition to the matter of hydrogen bonding versus hydrophobic interactions, the role of ionization as well as some applications of new knowledge gained are highlighted.
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| 47. |
- Lundberg, Mathias, et al.
(författare)
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Crill Measurements For Improved Fines Material Control
- 2018
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Ingår i: IMPC 2018. - Trondheim, Norway.
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Konferensbidrag (refereegranskat)abstract
- Finding the characterization method that best matches the pulping process is crucial in enabling the monitoring and control of pulp and final-product properties. Control of optimal process parameters in the production line are thus dependent on reliable and valid results. The Crill method is an analogue method based on the relationship between the interactions of lights of two different wavelengths (UV and IR) with the particles in the pulp. By comparing the specific UV and IR surfaces, the crill value is calculated. The crill method has been used in two studies with the aims to validate the crill measurement in a high yield pulping (HYP) process by focusing on refining and control of crill value of different pulp streams. The results indicate that the crill method can be used to monitor fibre treatment in refining processes. Moreover, by controlling pulp streams with regards to crill value, improvements of pulp strength and retention on the paper machine (PM) can be achieved.
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| 48. |
- Lundberg, Mathias, et al.
(författare)
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Validation of crill measurements in a high-yield pulp refining process for improved fines material control
- 2018
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Ingår i: Nordic Pulp & Paper Research Journal. - : Walter de Gruyter GmbH. - 0283-2631 .- 2000-0669. ; 33:2, s. 200-209
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Tidskriftsartikel (refereegranskat)abstract
- In high-yield pulp (HYP) refining, fine material is created by peeling action on the fibre surface. This fine material is usually characterized using conventional camera technology and image analysis. The smallest particles, the crill, also created in the refining process are too small to be visible in a camera image, and are therefore measured using light sources in the UV and IR wavelength spectrum. This research sought to determine whether the crill could be characterized in the presence of large fines material in a HYP refining process, and the results indicated that the larger fines material had little impact. In addition, the variation in crill measurements declined as the fibre treatment increased and remained low and stable during an extended period. Due to the great need to monitor and control pulp processes using rapid online measurements, cost-reduction actions at mills running close to specification targets put high demands on the measuring devices characterizing the production. The outcome of this study enables the use of the crill method to improve our knowledge of fibre treatment and its contribution to fibre adhesion in complex refining processes. Finally, combining conventional camera technology and the crill method could improve the overall fines material control.
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| 49. |
- Magalhães, Solange, et al.
(författare)
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Brief overview on bio-based adhesives and sealants
- 2019
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Ingår i: Polymers. - : MDPI AG. - 2073-4360. ; 11:10
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Tidskriftsartikel (refereegranskat)abstract
- Adhesives and sealants (AS) are materials with excellent properties, versatility, and simple curing mechanisms, being widely used in different areas ranging from the construction to the medical sectors. Due to the fast-growing demand for petroleum-based products and the consequent negative environmental impact, there is an increasing need to develop novel and more sustainable sources to obtain raw materials (monomers). This reality is particularly relevant for AS industries, which are generally dependent on non-sustainable fossil raw materials. In this respect, biopolymers, such as cellulose, starch, lignin, or proteins, emerge as important alternatives. Nevertheless, substantial improvements and developments are still required in order to simplify the synthetic routes, as well as to improve the biopolymer stability and performance of these new bio-based AS formulations. This environmentally friendly strategy will hopefully lead to the future partial or even total replacement of non-renewable petroleum-based feedstock. In this brief overview, the general features of typical AS are reviewed and critically discussed regarding their drawbacks and advantages. Moreover, the challenges faced by novel and more ecological alternatives, in particular lignocellulose-based solutions, are highlighted.
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| 50. |
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