366 results on '"Lars Berglund"'
Search Results
2. Polymer Films from Cellulose Nanofibrils—Effects from Interfibrillar Interphase on Mechanical Behavior
- Author
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Michael S. Reid, Erik Jungstedt, Lars Berglund, and Xuan Yang
- Subjects
chemistry.chemical_classification ,Materials science ,Molar mass ,Polymers and Plastics ,Organic Chemistry ,Sorption ,02 engineering and technology ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Materials Chemistry ,Polyethylene terephthalate ,Hemicellulose ,Interphase ,Surface charge ,Cellulose ,Composite material ,0210 nano-technology - Abstract
Dense polymeric films based on network-forming cellulose nanofibrils (CNFs) have excellent mechanical properties but are limited by moisture sensitivity. Here, interfibrillar effects from CNF surface properties are investigated. TEMPO-oxidized CNFs and two native CNFs are prepared with a similar length and width, to exclude geometrical effects. The CNFs have different surface properties in terms of sorbed hemicellulose content, hemicellulose molar mass, and surface charge. Moisture sorption, structural changes, and mechanical properties at different relative humidities are characterized. The presence of sorbed hemicelluloses in the interfibrillar interphase has favorable effects on the mechanical tensile properties. Surface-charged carboxyls increased moisture sorption and film thickness swelling and reduced the mechanical properties. A comparison with biaxially oriented polyethylene terephthalate films provides a perspective into the structure and properties of CNF films. The present study shows the importance of the interfibrillar interface and interphase region for mechanical film properties, including moisture effects.
- Published
- 2021
3. High-Strength Nanostructured Film Based on β-Chitin Nanofibrils from Squid Illex argentinus Pens by 2,2,6,6-Tetramethylpiperidin-1-yl Oxyl-Mediated Reaction
- Author
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Ngesa Ezekiel Mushi, Joakim Engström, Houssine Sehaqui, Qiong Wu, Lengwan Li, and Lars Berglund
- Subjects
Squid ,Nanocomposite ,biology ,Renewable Energy, Sustainability and the Environment ,General Chemical Engineering ,Biomaterial ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,biology.organism_classification ,01 natural sciences ,0104 chemical sciences ,Chitosan ,chemistry.chemical_compound ,Chitin ,chemistry ,Chemical engineering ,Nanofiber ,biology.animal ,Environmental Chemistry ,Biocomposite ,0210 nano-technology ,Illex argentinus - Abstract
2,2,6,6-Tetramethylpiperidin-1-yl oxyl (TEMPO)-oxidized beta-chitin nanofibrils (T-ChNF) are novel nanofibrils of high strength and stiffness and can also enhance the adsorption of chitosan in mate ...
- Published
- 2021
4. Surface Charges Control the Structure and Properties of Layered Nanocomposite of Cellulose Nanofibrils and Clay Platelets
- Author
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Qi Zhou, Dingfeng Xu, Shennan Wang, and Lars Berglund
- Subjects
Toughness ,Materials science ,Nanocomposite ,cellulose nanofibrils ,Ionic bonding ,02 engineering and technology ,mechanical properties ,010402 general chemistry ,021001 nanoscience & nanotechnology ,montmorillonite platelets ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Montmorillonite ,chemistry ,Chemical engineering ,nanocomposites ,Ultimate tensile strength ,General Materials Science ,Surface charge ,Cellulose ,surface charges ,0210 nano-technology ,Research Article ,Fire retardant - Abstract
The interfacial bonding and structure at the nanoscale in the polymer–clay nanocomposites are essential for obtaining desirable material and structure properties. Layered nanocomposite films of cellulose nanofibrils (CNFs)/montmorillonite (MTM) were prepared from the water suspensions of either CNFs bearing quaternary ammonium cations (Q-CNF) or CNFs bearing carboxylate groups (TO-CNF) with MTM nanoplatelets carrying net surface negative charges by using vacuum filtration followed by compressive drying. The effect of the ionic interaction between cationic or anionic charged CNFs and MTM nanoplatelets on the structure, mechanical properties, and flame retardant performance of the TO-CNF/MTM and Q-CNF/MTM nanocomposite films were studied and compared. The MTM nanoplatelets were well dispersed in the network of TO-CNFs in the form of nanoscale tactoids with the MTM content in the range of 5–70 wt %, while an intercalated structure was observed in the Q-CNF/MTM nanocomposites. The resulting TO-CNF/MTM nanocomposite films had a better flame retardant performance as compared to the Q-CNF/MTM films with the same MTM content. In addition, the effective modulus of MTM for the TO-CNF/MTM nanocomposites was as high as 129.9 GPa, 3.5 times higher than that for Q-CNF/MTM (37.1 GPa). On the other hand, the Q-CNF/MTM nanocomposites showed a synergistic enhancement in the modulus and tensile strength together with strain-to-failure and demonstrated a much better toughness as compared to the TO-CNF/MTM nanocomposites.
- Published
- 2021
5. Single step PAA delignification of wood chips for high-performance holocellulose fibers
- Author
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Anna Svedberg, Xuan Yang, Hans Grundberg, Lars Berglund, and Per-Oskar Westin
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chemistry.chemical_classification ,Molar mass ,Materials science ,Polymers and Plastics ,02 engineering and technology ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Peracetic acid ,Lignin ,Hemicellulose ,Fiber ,Cellulose ,Biocomposite ,0210 nano-technology - Abstract
Holocellulose fibers produced by mild delignification form strong fiber networks, without beating or dry-strength agents. Recently, sequential batch delignification using peracetic acid (PAA) on finely cut wood sticks resulted in high-quality holocellulose fibers. Here, single step PAA delignification is developed for wood chips, which is simpler and can be used for larger fiber batches (400 g) with similar, high yield (60%). Such fibers have 1.4% lignin, 25% hemicelluloses content and well-preserved cellulose and hemicellulose molar mass. The corresponding paper sheet materials with a porosity of ~ 50%, have a Young’s modulus of 9 GPa and a strength of 90 MPa. Holocellulose fibers can now be readily investigated for use in larger scale paper, molded fiber and polymer biocomposite materials applications, or for cellulose nanofibril preparation.
- Published
- 2021
6. Ice-templated nanocellulose porous structure enhances thermochemical storage kinetics in hydrated salt/graphite composites
- Author
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Federico Carosio, Francesco Cantamessa, Alberto Fina, Lilian Medina, Sergio Salviati, Guido Saracco, and Lars Berglund
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Materials science ,060102 archaeology ,Renewable Energy, Sustainability and the Environment ,Scanning electron microscope ,020209 energy ,Composite number ,06 humanities and the arts ,02 engineering and technology ,Energy storage ,Nanocellulose ,chemistry.chemical_compound ,Differential scanning calorimetry ,chemistry ,0202 electrical engineering, electronic engineering, information engineering ,Strontium bromide ,0601 history and archaeology ,Graphite ,Composite material ,Porosity - Abstract
The freeze-drying technique is employed for the production of novel strontium bromide/graphite/nanocellulose composites for thermochemical heat storage application. The aim is to obtain a better control and stability of salt organization within the composite, while maximizing the air/salt and salt/graphite interfacial areas and enhancing mass and heat transfer associated to the salt hydration and dehydration. A comparison with a conventional wet impregnation method is also reported. The morphology was investigated by means of scanning electron microscopy. Differential scanning calorimetry was employed to evaluate the energy storage density, while hydration kinetics were evaluated at 23 °C and 50% RH. The wet impregnation approach delivered materials with a limited porosity while freeze-drying produced highly porous structures with oriented channels for moisture transport across the composite. The organic binder provided an active contribution to the energy storage process, producing energy storage densities up to 764 kJ/kg, 48% greater than the theoretical value. Freeze-dried nanocellulose composites evidenced a significant increase of 54% in the hydration kinetics, compared to the pristine salt. Based on these results, the freeze-drying of ternary composites based on salt hydrate, graphite and nanocellulose is envisaged as a promising route for the production of fast charge and discharge thermochemical storage systems.
- Published
- 2020
7. Strongly Improved Mechanical Properties of Thermoplastic Biocomposites by PCL Grafting inside Holocellulose Wood Fibers
- Author
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Lars Berglund, Natalia Herrera, and Peter Olsén
- Subjects
chemistry.chemical_classification ,Thermoplastic ,Materials science ,Nanocomposite ,Renewable Energy, Sustainability and the Environment ,General Chemical Engineering ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Cellulose fiber ,chemistry ,Compounding ,Compatibility (mechanics) ,Environmental Chemistry ,Surface modification ,Extrusion ,Cellulose ,Composite material ,0210 nano-technology - Abstract
Chemical wood cellulose fiber modification is performed with the purpose to improve compatibility and induce nanofibrillation of the fibers during melt compounding of thermoplastic biocomposites. C...
- Published
- 2020
8. Top-Down Approach Making Anisotropic Cellulose Aerogels as Universal Substrates for Multifunctionalization
- Author
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Yuanyuan Li, Jonas Garemark, Licheng Sun, Xia Sheng, Ocean Cheung, Lars Berglund, and Xuan Yang
- Subjects
Solid-state chemistry ,biocomposite ,Materials science ,aerogel ,Materialkemi ,General Physics and Astronomy ,Kompositmaterial och -teknik ,anisotropy ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Article ,wood nanotechnology ,chemistry.chemical_compound ,Highly porous ,Polymerkemi ,Materials Chemistry ,General Materials Science ,Cellulose ,Composite material ,Anisotropy ,Composite Science and Engineering ,General Engineering ,Pappers-, massa- och fiberteknik ,Aerogel ,Paper, Pulp and Fiber Technology ,Polymer Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,top-down ,Biocomposite ,0210 nano-technology - Abstract
Highly porous, strong aerogels with anisotropicstructural properties are of great interest for multifunctionalmaterials for applications including insulators in buildings,filters for oil cleanup, electrical storage devices,etc. Contem-porary aerogels are mostly extracted from fossil resources andsynthesized from bottom-up techniques, often requiring addi-tional strategies to obtain high anisotropy. In this work, auniversal approach to prepare porous, strong, anisotropicaerogels is presented through exploiting the natural hierarchicaland anisotropic structure of wood. The preparation comprisesnanoscale removal of lignin, followed by dissolution−regener-ation of nanofibers, leading to enhanced cell wall porosity with nanofibrillated networks occupying the pore space in thecellular wood structure. The aerogels retain structural anisotropy of natural wood, exhibit specific surface areas up to 247 m2/g, and show high compression strength at 95% porosity. This is a record specific area value for wood aerogels/foams and evenhigher than most cellulose-based aerogels for its assigned strength. The aerogel can serve as a platform for multifunctionalcomposites including scaffolds for catalysis, gas separation, or liquid purification due to its porous matrix or as binder-freeelectrodes in electronics. To demonstrate the multifunctionality, the aerogels are successfully decorated with metalnanoparticles (Ag) and metal oxide nanoparticles (TiO2)byin situsynthesis, coated by the conductive polymer(PEDOT:PSS), and carbonized to yield conductive aerogels. This approach is found to be a universal way to prepare highlyporous anisotropic aerogels. QC 20200918
- Published
- 2020
9. Lignin-Based Epoxy Resins: Unravelling the Relationship between Structure and Material Properties
- Author
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Claudio Gioia, Olena Sevastyanova, Martino Colonna, Ayumu Tagami, Martin Lawoko, Lars Berglund, Lilian Medina, Gioia C., Colonna M., Tagami A., Medina L., Sevastyanova O., Berglund L.A., and Lawoko M.
- Subjects
Polymers and Plastics ,Chemical structure ,Thermosetting polymer ,Bioengineering ,02 engineering and technology ,Chemical Fractionation ,010402 general chemistry ,Lignin ,01 natural sciences ,Article ,Biomaterials ,chemistry.chemical_compound ,Ultimate tensile strength ,Materials Chemistry ,Molecule ,Eucalyptus ,Molar mass ,Epoxy Resins ,Epoxy ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Molecular Weight ,Chemical engineering ,Kraft process ,chemistry ,visual_art ,visual_art.visual_art_medium ,0210 nano-technology - Abstract
Here we investigate the relationship between thermomechanical properties and chemical structure of well-characterized lignin-based epoxy resins. For this purpose, technical lignins from eucalyptus and spruce, obtained from the Kraft process, were used. The choice of lignins was based on the expected differences in molecular structure. The lignins were then refined by solvent fractionation, and three fractions with comparable molecular weights were selected to reduce effects of molar mass on the properties of the final thermoset resins. Consequently, any differences in thermomechanical properties are expected to correlate with molecular structure differences between the lignins. Oxirane moieties were selectively introduced to the refined fractions, and the resulting lignin epoxides were subsequently cross-linked with two commercially available polyether diamines (Mn = 2000 and 400) to obtain lignin-based epoxy resins. Molecular-scale characterization of the refined lignins and their derivatives were performed by 31P NMR, 2D-NMR, and DSC methods to obtain the detailed chemical structure of original and derivatized lignins. The thermosets were studied by DSC, DMA, and tensile tests and demonstrated diverse thermomechanical properties attributed to structural components in lignin and selected amine cross-linker. An epoxy resin with a lignin content of 66% showed a Tg of 79 °C from DMA, Young's modulus of 1.7 GPa, tensile strength of 66 MPa, and strain to failure of 8%. The effect of molecular lignin structure on thermomechanical properties was analyzed, finding significant differences between the rigid guaiacyl units in spruce lignin compared with sinapyl units in eucalyptus lignin. The methodology points toward rational design of molecularly tailored lignin-based thermosets.
- Published
- 2020
10. Cellulose and the role of hydrogen bonds : not in charge of everything
- Author
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Tobias Benselfelt, Lars Wågberg, Jakob Wohlert, Malin Wohlert, István Furó, and Lars Berglund
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Hydrogen bonding ,Molecular interactions ,Materials science ,Polymers and Plastics ,Polymer science ,Hydrogen bond ,Computer modeling ,Pappers-, massa- och fiberteknik ,Molecular simulation ,Charge (physics) ,Paper, Pulp and Fiber Technology ,chemistry.chemical_compound ,chemistry ,Cellulose ,Nanomaterials - Abstract
In the cellulose scientific community, hydrogen bonding is often used as the explanation for a large variety of phenomena and properties related to cellulose and cellulose based materials. Yet, hydrogen bonding is just one of several molecular interactions and furthermore is both relatively weak and sensitive to the environment. In this review we present a comprehensive examination of the scientific literature in the area, with focus on theory and molecular simulation, and conclude that the relative importance of hydrogen bonding has been, and still is, frequently exaggerated.
- Published
- 2022
11. Bench-scale fire stability testing – Assessment of protective systems on carbon fibre reinforced polymer composites
- Author
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Weronika Tabaka, Lars Berglund, Sebastian Timme, Tobias Lauterbach, Lilian Medina, Sophie Duquesne, Bernhard Schartel, and Federico Carosio
- Subjects
chemistry.chemical_classification ,Nanocomposite ,Materials science ,Polymers and Plastics ,Stability test ,Protective coatings ,Organic Chemistry ,Polymer ,Carbon fibre reinforced polymer ,Compressive strength ,TP1080-1185 ,chemistry ,Fire protection ,Heat shield ,Bench-scale fire resistance testing ,Polymer composites ,Fire stability ,Polymers and polymer manufacture ,Composite material ,Intumescent - Abstract
Fire resistance testing of components made of carbon fibre reinforced polymers (CFRP) usually demands intermediate-scale or full-scale testing. A bench-scale test is presented as a practicable and efficient method to assess how different fire protective systems improve the structural integrity of CFRPs during fire. The direct flame of a fully developed fire was applied to one side of the CFRP specimen, which was simultaneously loaded with compressive force. Three different approaches (film, non-woven, and coatings) were applied: paper with a thickness in the range of μm consisting of cellulose nanofibre (CNF)/clay nanocomposite, nonwoven mats with thickness in the range of cm and intumescent coatings with a thickness in the range of mm. The uncoated specimen failed after just 17 s. Protection by these systems provides fire stability, as they multiply the time to failure by as much as up to 43 times. The reduced heating rates of the protected specimens demonstrate the reduced heat penetration, indicating the coatings’ excellent heat shielding properties. Bench-scale fire stability testing is shown to be suitable tool to identify, compare and assess different approaches to fire protection.
- Published
- 2021
12. Sustainable Wood Nanotechnologies for Wood Composites Processed by In-Situ Polymerization
- Author
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Céline Montanari, Peter Olsén, and Lars Berglund
- Subjects
Green chemistry ,Materials science ,biocomposite ,nanostructure ,building material ,Building material ,02 engineering and technology ,engineering.material ,010402 general chemistry ,01 natural sciences ,7. Clean energy ,Nanocellulose ,wood nanotechnology ,biopolymer ,In situ polymerization ,Composite material ,QD1-999 ,nanocellulose ,chemistry.chemical_classification ,Nanocomposite ,Moisture ,nanocomposite ,technology, industry, and agriculture ,Pappers-, massa- och fiberteknik ,General Chemistry ,Polymer ,Paper, Pulp and Fiber Technology ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Chemistry ,chemistry ,13. Climate action ,Perspective ,engineering ,Biocomposite ,0210 nano-technology - Abstract
The development of large, multifunctional structures from sustainable wood nanomaterials is challenging. The need to improve mechanical performance, reduce moisture sensitivity, and add new functionalities, provides motivation for nanostructural tailoring. Although existing wood composites are commercially successful, materials development has not targeted nano-structural control of the wood cell wall, which could extend the property range. For sustainable development, non-toxic reactants, green chemistry and processing, lowered cumulative energy requirements, and lowered CO2-emissions are important targets. Here, modified wood substrates in the form of veneer are suggested as nanomaterial components for large, load-bearing structures. Examples include polymerization of bio-based monomers inside the cell wall, green chemistry wood modification, and addition of functional inorganic nanoparticles inside the cell wall. The perspective aims to describe bio-based polymers and green processing concepts for this purpose, along with wood nanoscience challenges.
- Published
- 2021
13. Dynamic Nanocellulose Networks for Thermoset-like yet Recyclable Plastics with a High Melt Stiffness and Creep Resistance
- Author
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Antal Boldizar, Ramiro Rojas, Anna Peterson, Christian Müller, Martin Andersson, Lars Berglund, Ida Östergren, Johannes Thunberg, Abhijit Venkatesh, Anna Ström, and A. Lotsari
- Subjects
Thermoplastic ,Materials science ,Polymers and Plastics ,Polymers ,Composite number ,Thermosetting polymer ,Bioengineering ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Nanocellulose ,Biomaterials ,chemistry.chemical_compound ,Viscosity ,Materials Chemistry ,Composite material ,Cellulose ,chemistry.chemical_classification ,Temperature ,Polymer ,Polyethylene ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,Creep ,Printing, Three-Dimensional ,Nanoparticles ,0210 nano-technology ,Plastics - Abstract
Many polymers, including polyethylene, feature a relatively low melting point and hence must be cross-linked to make them viable for applications that demand a high stiffness and creep resistance at elevated temperatures. The resulting thermoset plastics cannot be recycled, and therefore alternative materials with a reconfigurable internal network structure are in high demand. Here, we establish that such a thermoset-like yet recyclable material can be realized through the addition of a nanocellulose reinforcing agent. A network consisting of cellulose nanocrystals, nano- or microfibrils imparts many of the characteristics that are usually achieved through chemical cross-linking. For instance, the addition of only 7.5 wt % of either nanocellulose material significantly enhances the melt stiffness of an otherwise molten ethylene-acrylate copolymer by at least 1 order of magnitude. At the same time, the nanocellulose network reduces the melt creep elongation to less than 10%, whereas the neat molten matrix would rupture. At high shear rates, however, the molten composites do not display a significantly higher viscosity than the copolymer matrix, and therefore retain the processability of a thermoplastic material. Repeated re-extrusion at 140 °C does not compromise the thermomechanical properties, which indicates a high degree of recyclability. The versatility of dynamic nanocellulose networks is illustrated by 3D printing of a cellulose composite, where the high melt stiffness improves the printability of the resin.
- Published
- 2019
14. Molecular Engineering of the Cellulose-Poly(Caprolactone) Bio-Nanocomposite Interface by Reactive Amphiphilic Copolymer Nanoparticles
- Author
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Andrea Träger, Lars Berglund, Giada Lo Re, Eva Malmström, and Tahani Kaldéus
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Nanocomposite ,Materials science ,General Engineering ,General Physics and Astronomy ,Nanoparticle ,02 engineering and technology ,Dynamic mechanical analysis ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Methacrylate ,01 natural sciences ,0104 chemical sciences ,Nanocellulose ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Copolymer ,General Materials Science ,Biocomposite ,0210 nano-technology ,Caprolactone - Abstract
A molecularly engineered water-borne reactive compatibilizer is designed for tuning of the interface in melt-processed thermoplastic poly(caprolactone) (PCL)-cellulose nanocomposites. The mechanical properties of the nanocomposites are studied by tensile testing and dynamic mechanical analysis. The reactive compatibilizer is a statistical copolymer of 2-(dimethylamino)ethyl methacrylate and 2-hydroxy methacrylate, which is subsequently esterified and quaternized. Quaternized ammonium groups in the reactive compatibilizer electrostatically match the negative surface charge of cellulose nanofibrils (CNFs). This results in core-shell CNFs with a thin uniform coating of the compatibilizer. This promotes the dispersion of CNFs in the PCL matrix, as concluded from high-resolution scanning electron microscopy and atomic force microscopy. Moreover, the compatibilizer "shell" has methacrylate functionalities, which allow for radical reactions during processing and links covalently with PCL. Compared to the bio-nanocomposite reference, the reactive compatibilizer (
- Published
- 2019
15. Lytic polysaccharide monooxygenase (LPMO) mediated production of ultra-fine cellulose nanofibres from delignified softwood fibres
- Author
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Qi Zhou, Xuan Yang, Kai Li, Vincent Bulone, Salla Koskela, Dingfeng Xu, Lars Berglund, Lauren S. McKee, and Shennan Wang
- Subjects
chemistry.chemical_classification ,Softwood ,010405 organic chemistry ,Chemistry ,Monooxygenase ,010402 general chemistry ,Polysaccharide ,01 natural sciences ,Pollution ,0104 chemical sciences ,chemistry.chemical_compound ,Lytic cycle ,Chemical engineering ,Environmental Chemistry ,Ultra fine ,Cellulose - Abstract
An environmentally friendly, energy-efficient method for cellulose nanofibre (CNF) production from softwood holocellulose utilising oxidative enzymes, lytic polysaccharide monooxygenases (LPMOs).
- Published
- 2019
16. Quantifying Localized Macromolecular Dynamics within Hydrated Cellulose Fibril Aggregates
- Author
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Lars Berglund, Jakob Wohlert, Pan Chen, Camilla Terenzi, and István Furó
- Subjects
Materials science ,Polymers and Plastics ,Organic Chemistry ,Biophysics ,02 engineering and technology ,Carbon-13 NMR ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Fibril ,01 natural sciences ,0104 chemical sciences ,Amorphous solid ,Inorganic Chemistry ,chemistry.chemical_compound ,Molecular dynamics ,Adsorption ,Biofysica ,chemistry ,Chemical physics ,Materials Chemistry ,Relaxation (physics) ,Life Science ,Cellulose ,0210 nano-technology ,Macromolecule - Abstract
Molecular dynamics (MD) simulations of 13C NMR longitudinal relaxation (T1) distributions were recently established as a powerful tool for characterizing moisture adsorption in natural amorphous polymers. Here, such computational-experimental synergy is demonstrated in a system with intrinsically high structural heterogeneity, namely crystalline cellulose nanofibrils (CNFs) in highly hydrated aggregated state. In such a system, structure-function properties on the nanoscale remain largely uncovered by experimental means alone. In this work, broadly polydispersed experimental 13C NMR T1 distributions could be successfully reproduced in simulations and, for the first time, were decomposed into contributions from distinct molecular sources within the aggregated CNFs, namely, (i) the core and (ii) the less-accessible and accessible surface regions of the CNFs. Furthermore, within the surface groups structurally different sites such as (iii) residues with different hydroxymethyl orientations and (iv) center and origin chains could be discerned based on their distinct molecular dynamics. The MD simulations unravel a direct correlation between dynamical and structural heterogeneity at an atomistic-level resolution that cannot be accessed by NMR experiments. The proposed approach holds the potential to enable quantitative interpretation of NMR data from a range of multicomponent high-performance nanocomposites with significantly heterogeneous macromolecular structure.
- Published
- 2019
17. Transforming technical lignins to structurally defined star-copolymers under ambient conditions
- Author
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Peter Olsén, Mats Johansson, Lars Berglund, Martin Lawoko, and Marcus Jawerth
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010405 organic chemistry ,Kinetics ,010402 general chemistry ,01 natural sciences ,Pollution ,0104 chemical sciences ,Characterization (materials science) ,chemistry.chemical_compound ,Monomer ,chemistry ,Chemical engineering ,Scientific method ,Copolymer ,Environmental Chemistry ,Lignin ,Carbonate ,Macromolecule - Abstract
Transforming biomass derived components to materials with controlled and predictable properties is a major challenge. Current work describes the controlled synthesis of starcopolymers with functional and degradable arms from the Lignoboost® process. Macromolecular control is achieved by combining lignin fractionation and characterization with ring-opening copolymerization (ROCP). The cyclic monomers used are e-caprolactone (eCL) and a functional carbonate monomer, 2-allyloxymethyl-2-ethyltrimethylene carbonate (AOMEC). The synthesis is performed at ambient temperature, under bulk conditions, in an open flask, and the graft composition and allyl functionality distribution are controlled by the copolymerization kinetics. Emphasis is placed on understanding the initiation efficiency, structural changes to the lignin backbone and the final macromolecular architecture. The present approach provides a green, scalable and cost effective protocol to create well-defined functional macromolecules from technical lignins.
- Published
- 2019
18. High strength nanostructured films based on well-preserved β-chitin nanofibrils
- Author
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Maria Soltésova, Qiong Wu, Ngesa Ezekiel Mushi, Erik Jungstedt, and Lars Berglund
- Subjects
Materials science ,Morphology (linguistics) ,Nanofibers ,Chitin ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Nanomaterials ,chemistry.chemical_compound ,biology.animal ,Animals ,General Materials Science ,Particle Size ,Squid ,Molar mass ,biology ,Extraction (chemistry) ,Decapodiformes ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,Chemical engineering ,Particle size ,Crystallite ,0210 nano-technology - Abstract
Chitin nanofibrils (ChNF) are interesting high-value constituents for nanomaterials due to the enormous amount of waste from the seafood industry. So far, the reported ChNFs are substantially modified and chemically degraded (shortened) during extraction from the organisms. Here, highly individualized and long native-state β-chitin nanofibrils from Illex argentinus squid pens are prepared. A mild treatment was developed to preserve the molar mass, aspect ratio, degree of acetylation and crystallite structure. The fibrils show a uniform diameter of 2-7 nm, very high aspect ratio (up to 750), high degree of acetylation (DA = 99%), and high molar mass (843 500 dalton). The powder X-ray diffraction analysis showed the preserved crystallite structure after protein removal. These "high quality" ChNFs were used to prepare nanostructured films via vacuum filtration from stable hydrocolloids. The effects of well-preserved "native" fibrils on morphology, and film properties (mechanical and optical), were studied and compared with earlier results based on coarser and shorter, chemically degraded chitin fibrils.
- Published
- 2019
19. Towards optimised size distribution in commercial microfibrillated cellulose: a fractionation approach
- Author
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Goksu Cinar Ciftci, Hans Henrik Ovrebo, Anastasia V. Riazanova, Lars Wågberg, Ramiro Rojas, Lars Berglund, and Per Larsson
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Polymers and Plastics ,02 engineering and technology ,Fractionation ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,body regions ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Bioorganic chemistry ,Cellulose ,0210 nano-technology - Abstract
For the successful commercialisation of microfibrillated cellulose (MFC) it is of utmost importance to carefully characterise the constituent cellulose particles. This could for instance lead to th ...
- Published
- 2018
20. Strong and Tough Chitin Film from α-Chitin Nanofibers Prepared by High Pressure Homogenization and Chitosan Addition
- Author
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Lars Berglund, Qi Zhou, Ngesa Ezekiel Mushi, and Takashi Nishino
- Subjects
Materials science ,Nanostructure ,Renewable Energy, Sustainability and the Environment ,General Chemical Engineering ,Portable water purification ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Nanomaterials ,Chitosan ,chemistry.chemical_compound ,High pressure homogenization ,chemistry ,Chitin ,Chemical engineering ,Nanofiber ,Environmental Chemistry ,0210 nano-technology - Abstract
Chitin nanofibers are an interesting biological nanomaterial for advanced applications, for example, in medicine, electronics, packaging and water purification. The challenge is to separate chitin ...
- Published
- 2018
21. Olive Stone Delignification Toward Efficient Adsorption of Metal Ions
- Author
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Ying Gao, Maria del Carmen Aliques Tomas, Jonas Garemark, Xia Sheng, Lars Berglund, and Yuanyuan Li
- Subjects
delignification ,White powder ,Chemistry ,olive stone ,lcsh:T ,Materials Science (miscellaneous) ,Metal ions in aqueous solution ,02 engineering and technology ,010501 environmental sciences ,021001 nanoscience & nanotechnology ,Pulp and paper industry ,01 natural sciences ,lcsh:Technology ,metal ion ,Metal ,Waste product ,Adsorption ,Metal ion adsorption ,visual_art ,Specific surface area ,visual_art.visual_art_medium ,biosorbent ,white powder ,0210 nano-technology ,0105 earth and related environmental sciences - Abstract
Olive stone is an important biomaterial waste product generated in large amount. As a lignocellulose material, olive stone could be a sustainable resource for biosorbents. In this work, olive stone powder delignification using sodium chlorite (NaClO2) was performed to enhance metal ion adsorption capacity. The influence of the treatment on olive stone powder physical-chemical properties was studied, including specific surface area, surface chemistry, morphology, etc. The white, delignified olive stone powder was applied for metal ions (Fe3+, Cu2+, and Zn2+) adsorption. Olive stone delignification not only increases the accessibility of the olive stone powder but also broadens the applications to materials design with optical functions by the generation of a white powder.
- Published
- 2021
22. Strong reinforcement effects in 2D cellulose nanofibril–graphene oxide (CNF–GO) nanocomposites due to GO-induced CNF ordering
- Author
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Pan Chen, Giada Lo Re, Lars Berglund, Hanieh Mianehrow, Per Tomas Larsson, Federico Carosio, and Alberto Fina
- Subjects
Nanostructure ,Materials science ,Oxide ,Modulus ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Article ,law.invention ,chemistry.chemical_compound ,law ,Teknik och teknologier ,Ultimate tensile strength ,General Materials Science ,Cellulose ,Composite material ,Nanocomposite ,Renewable Energy, Sustainability and the Environment ,Small-angle X-ray scattering ,Graphene ,General Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,Engineering and Technology ,0210 nano-technology - Abstract
Nanocomposites from native cellulose with low 2D nanoplatelet content are of interest as sustainable materials combining functional and structural performance. Cellulose nanofibril–graphene oxide (CNF–GO) nanocomposite films are prepared by a physical mixing–drying method, with a focus on low GO content, the use of very large GO platelets (2–45 μm) and nanostructural characterization using synchrotron X-ray source for WAXS and SAXS. These nanocomposites can be used as transparent coatings, strong films or membranes, as gas barriers or in laminated form. CNF nanofibrils with random in-plane orientation, form a continuous non-porous matrix with GO platelets oriented in-plane. GO reinforcement mechanisms in CNF are investigated, and relationships between nanostructure and suspension rheology, mechanical properties, optical transmittance and oxygen barrier properties are investigated as a function of GO content. A much higher modulus reinforcement efficiency is observed than in previous polymer–GO studies. The absolute values for modulus and ultimate strength are as high as 17 GPa and 250 MPa at a GO content as small as 0.07 vol%. The remarkable reinforcement efficiency is due to improved organization of the CNF matrix; and this GO-induced mechanism is of general interest for nanostructural tailoring of CNF-2D nanoplatelet composites.
- Published
- 2020
23. Mild and Versatile Functionalization of Nacre-Mimetic Cellulose Nanofibrils/Clay Nanocomposites by Organocatalytic Surface Engineering
- Author
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Lilian Medina, Luca Deiana, Lars Berglund, Armando Córdova, and Rana Alimohammadzadeh
- Subjects
Nanocomposite ,Materials science ,General Chemical Engineering ,Nanotechnology ,General Chemistry ,Kemi ,Surface engineering ,Article ,chemistry.chemical_compound ,Chemistry ,chemistry ,Chemical Sciences ,Surface modification ,Cellulose ,QD1-999 - Abstract
Development of surface-engineering strategies, which are facile, versatile, and mild, are highly desirable in tailor-made functionalization of high-performance bioinspired nanocomposites. We herein disclose for the first time a general organocatalytic strategy for the functionalization and hydrophobization of nacre-mimetic nanocomposites, which includes vide supra key aspects of surface engineering. The merging of metal-free catalysis and the design of nacre-mimetic nanocomposite materials were demonstrated by the organocatalytic surface engineering of cellulose nanofibrils/clay nanocomposites providing the corresponding bioinspired nanocomposites with good mechanical properties, hydrophobicity, and useful thia-, amino, and olefinic functionalities.
- Published
- 2020
24. Tailoring Nanocellulose–Cellulose Triacetate Interfaces by Varying the Surface Grafting Density of Poly(ethylene glycol)
- Author
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Akihiro Masuda, Tsuguyuki Saito, Shuji Fujisawa, Hiroto Soeta, Akira Isogai, Lars Berglund, and Giada Lo Re
- Subjects
chemistry.chemical_classification ,Poly ethylene glycol ,Materials science ,Nanocomposite ,General Chemical Engineering ,02 engineering and technology ,General Chemistry ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Grafting ,01 natural sciences ,Article ,0104 chemical sciences ,Nanocellulose ,lcsh:Chemistry ,Cellulose triacetate ,chemistry.chemical_compound ,lcsh:QD1-999 ,chemistry ,Chemical engineering ,0210 nano-technology - Abstract
Careful design of the structures of interfaces between nanofillers and polymer matrices can significantly improve the mechanical and thermal properties of the overall nanocomposites. Here, we investigate how the grafting density on the surface of nanocelluloses influences the properties of nanocellulose/cellulose triacetate (CTA) composites. The surface of nanocellulose, which was prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl oxidation, was modified with long poly(ethylene glycol) (PEG) chains at different grafting densities. The PEG-grafted nanocelluloses were homogeneously embedded in CTA matrices. The mechanical and thermal properties of the nanocomposites were characterized. Increasing the grafting density caused the soft PEG chains to form denser and thicker layers around the rigid nanocelluloses. The PEG layers were not completely miscible with the CTA matrix. This structure considerably enhanced the energy dissipation by allowing sliding at the interface, which increased the toughness of the nanocomposites. The thermal and mechanical properties of the composites could be tailored by controlling the grafting density. These findings provide a deeper understanding about interfacial design for nanocellulose-based composite materials.
- Published
- 2018
25. Toward Sustainable Multifunctional Coatings Containing Nanocellulose in a Hybrid Glass Matrix
- Author
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Yichuan Ding, Farhan Ansari, Reinhold H. Dauskardt, and Lars Berglund
- Subjects
Zirconium ,Materials science ,Nanocomposite ,General Engineering ,General Physics and Astronomy ,chemistry.chemical_element ,02 engineering and technology ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Silane ,0104 chemical sciences ,Nanocellulose ,Contact angle ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Coating ,Alkoxide ,engineering ,General Materials Science ,0210 nano-technology ,Sol-gel - Abstract
We report on a sustainable route to protective nanocomposite coatings, where one of the components, nanocellulose fibrils, is derived from trees and the glass matrix is an inexpensive sol-gel organic-inorganic hybrid of zirconium alkoxide and an epoxy-functionalized silane. The hydrophilic nature of the colloidal nanocellulose fibrils is exploited to obtain a homogeneous one-pot suspension of the nanocellulose in the aqueous sol-gel matrix precursors solution. The mixture is then sprayed to form nanocomposite coatings of a well-dispersed, random in-plane nanocellulose fibril network in a continuous organic-inorganic glass matrix phase. The nanocellulose incorporation in the sol-gel matrix resulted in nanostructured composites with marked effects on salient coating properties including optical transmittance, hardness, fracture energy, and water contact angle. The particular role of the nanocellulose fibrils on coating fracture properties, important for coating reliability, was analyzed and discussed in terms of fibril morphology, molecular matrix, and nanocellulose/matrix interactions.
- Published
- 2018
26. Improved Cellulose Nanofibril Dispersion in Melt-Processed Polycaprolactone Nanocomposites by a Latex-Mediated Interphase and Wet Feeding as LDPE Alternative
- Author
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Qiong Wu, Richard T. Olsson, Lars Berglund, Eva Malmström, Ulf W. Gedde, Giada Lo Re, and Joakim Engström
- Subjects
Materials science ,Nanocomposite ,Nanoparticle ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Low-density polyethylene ,chemistry.chemical_compound ,chemistry ,Ultimate tensile strength ,Polycaprolactone ,General Materials Science ,Cellulose ,Composite material ,Methyl methacrylate ,0210 nano-technology ,Dispersion (chemistry) - Abstract
This work reports the development of a sustainable and green one-step wet-feeding method to prepare tougher and stronger nanocomposites from biodegradable cellulose nanofibrils (CNF)/polycaprolactone (PCL) constituents, compatibilized with reversible addition fragmentation chain transfer-mediated surfactant-free poly(methyl methacrylate) (PMMA) latex nanoparticles. When a PMMA latex is used, a favorable electrostatic interaction between CNF and the latex is obtained, which facilitates mixing of the constituents and hinders CNF agglomeration. The improved dispersion is manifested in significant improvement of mechanical properties compared with the reference material. The tensile tests show much higher modulus (620 MPa) and strength (23 MPa) at 10 wt % CNF content (compared to the neat PCL reference modulus of 240 and 16 MPa strength), while maintaining high level of work to fracture the matrix (7 times higher than the reference nanocomposite without the latex compatibilizer). Rheological analysis showed a...
- Published
- 2018
27. Hydration-Dependent Dynamical Modes in Xyloglucan from Molecular Dynamics Simulation of 13C NMR Relaxation Times and Their Distributions
- Author
-
Camilla Terenzi, Jakob Wohlert, István Furó, Pan Chen, and Lars Berglund
- Subjects
chemistry.chemical_classification ,Work (thermodynamics) ,Materials science ,Polymers and Plastics ,Relaxation (NMR) ,Bioengineering ,02 engineering and technology ,Polymer ,Carbon-13 NMR ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Biomaterials ,Xyloglucan ,Molecular dynamics ,chemistry.chemical_compound ,chemistry ,Chemical physics ,Materials Chemistry ,Life Science ,Molecule ,0210 nano-technology ,Macromolecule - Abstract
Macromolecular dynamics in biological systems, which play a crucial role for biomolecular function and activity at ambient temperature, depend strongly on moisture content. Yet, a generally accepted quantitative model of hydration-dependent phenomena based on local relaxation and diffusive dynamics of both polymer and its adsorbed water is still missing. In this work, atomistic-scale spatial distributions of motional modes are calculated using molecular dynamics simulations of hydrated xyloglucan (XG). These are shown to reproduce experimental hydration-dependent 13 C NMR longitudinal relaxation times (T 1 ) at room temperature, and relevant features of their broad distributions, which are indicative of locally heterogeneous polymer reorientational dynamics. At low hydration, the self-diffusion behavior of water shows that water molecules are confined to particular locations in the randomly aggregated XG network while the average polymer segmental mobility remains low. Upon increasing water content, the hydration network becomes mobile and fully accessible for individual water molecules, and the motion of hydrated XG segments becomes faster. Yet, the polymer network retains a heterogeneous gel-like structure even at the highest level of hydration. We show that the observed distribution of relaxations times arises from the spatial heterogeneity of chain mobility that in turn is a result of heterogeneous distribution of water-chain and chain-chain interactions. Our findings contribute to the picture of hydration-dependent dynamics in other macromolecules such as proteins, DNA, and synthetic polymers, and hold important implications for the mechanical properties of polysaccharide matrixes in plants and plant-based materials.
- Published
- 2018
28. Preparation and evaluation of high-lignin content cellulose nanofibrils from eucalyptus pulp
- Author
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Martha Herrera, Pim-on Rujitanaroj, Ramiro Rojas, Lars Berglund, Xuan Yang, and Kasinee Thitiwutthisakul
- Subjects
Materials science ,Polymers and Plastics ,Pulp (paper) ,technology, industry, and agriculture ,02 engineering and technology ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Eucalyptus ,0104 chemical sciences ,Catalysis ,Contact angle ,chemistry.chemical_compound ,Oxygen transmission rate ,chemistry ,Chemical engineering ,engineering ,Lignin ,Cellulose ,0210 nano-technology ,Chemical composition - Abstract
High Klason lignin content (23 wt%) cellulose nanofibrils (LCNF) were successfully isolated from eucalyptus pulp through catalyzed chemical oxidation, followed by high-pressure homogenization. LCNFs had a diameter of ca. 13 nm according to AFM evaluation. Dense films were obtained through vacuum filtration (nanopaper) and subjected to different drying methods. When drying under heat and mild vacuum (93 °C, 95 kPa) a higher water contact angle, lower roughness and oxygen transmission rate were observed, compared to those drying at room temperature under compression conditions. DSC experiments showed difference in signals associated to Tg of LCNF compared to CNF produced from spruce bleached pulp through enzymatic pre-treatment. The LCNF-based nanopaper showed mechanical properties slightly lower than for those made from cellulose nanofibrils, yet with increased hydrophobicity. In summary, the high-lignin content cellulose nanofibrils proved to be a suitable material for the production of low oxygen permeability nanopaper, with chemical composition close to native wood.
- Published
- 2018
29. Toward Semistructural Cellulose Nanocomposites: The Need for Scalable Processing and Interface Tailoring
- Author
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Farhan Ansari and Lars Berglund
- Subjects
Materials science ,Polymers and Plastics ,Interface (computing) ,Nanofibers ,Modulus ,Bioengineering ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Nanocomposites ,Nanocellulose ,Biomaterials ,chemistry.chemical_compound ,Materials Chemistry ,Cellulose ,chemistry.chemical_classification ,Nanocomposite ,Economies of agglomeration ,Polymer ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,Scalability ,0210 nano-technology - Abstract
Cellulose nanocomposites can be considered for semistructural load-bearing applications where modulus and strength requirements exceed 10 GPa and 100 MPa, respectively. Such properties are higher than for most neat polymers but typical for molded short glass fiber composites. The research challenge for polymer matrix biocomposites is to develop processing concepts that allow high cellulose nanofibril (CNF) content, nanostructural control in the form of well-dispersed CNF, the use of suitable polymer matrices, as well as molecular scale interface tailoring to address moisture effects. From a practical point of view, the processing concept needs to be scalable so that large-scale industrial processing is feasible. The vast majority of cellulose nanocomposite studies elaborate on materials with low nanocellulose content. An important reason is the challenge to prevent CNF agglomeration at high CNF content. Research activities are therefore needed on concepts with the potential for rapid processing with controlled nanostructure, including well-dispersed fibrils at high CNF content so that favorable properties are obtained. This perspective discusses processing strategies, agglomeration problems, opportunities, and effects from interface tailoring. Specifically, preformed CNF mats can be used to design nanostructured biocomposites with high CNF content. Because very few composite materials combine functional and structural properties, CNF materials are an exception in this sense. The suggested processing concept could include functional components (inorganic clays, carbon nanotubes, magnetic nanoparticles, among others). In functional three-phase systems, CNF networks are combined with functional components (nanoparticles or fibril coatings) together with a ductile polymer matrix. Such materials can have functional properties (optical, magnetic, electric, etc.) in combination with mechanical performance, and the comparably low cost of nanocellulose may facilitate the use of large nanocomposite structures in industrial applications.
- Published
- 2018
30. Nematic structuring of transparent and multifunctional nanocellulose papers
- Author
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Mengchen Zhao, Michiko Shimizu, Farhan Ansari, Tsuguyuki Saito, Miyuki Takeuchi, Lars Berglund, and Akira Isogai
- Subjects
Materials science ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Structuring ,0104 chemical sciences ,Nanocellulose ,chemistry.chemical_compound ,chemistry ,Liquid crystal ,Nanofiber ,Engineering tool ,General Materials Science ,Cellulose ,0210 nano-technology - Abstract
The nematic structuring of cellulose nanofibers (CNFs) is proposed as a nanostructural engineering tool for exploiting the potential of CNFs in conceptually new "transparent papers". The nematic-structured CNF papers exhibit superior mechanical properties, optical transparency, gas-barrier properties, heat transfer properties and electrical resistivity, compared with conventional randomly-structured CNF papers.
- Published
- 2018
31. Nanocellulose Xerogel as Template for Transparent, Thick, Flame-Retardant Polymer Nanocomposites
- Author
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Lars Berglund, Shuji Fujisawa, Tsuguyuki Saito, and Wataru Sakuma
- Subjects
Materials science ,Polymer nanocomposite ,General Chemical Engineering ,02 engineering and technology ,010402 general chemistry ,Methacrylate ,01 natural sciences ,Article ,Nanocellulose ,chemistry.chemical_compound ,General Materials Science ,Composite material ,QD1-999 ,cellulose nanofibers ,chemistry.chemical_classification ,Nanocomposite ,nanocomposite ,Flexural modulus ,xerogel ,flame-retardant ,Polymer ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Chemistry ,Monomer ,chemistry ,Nanofiber ,0210 nano-technology - Abstract
Cellulose nanofibers (CNFs) have excellent properties, such as high strength, high specific surface areas (SSA), and low coefficients of thermal expansion (CTE), making them a promising candidate for bio-based reinforcing fillers of polymers. A challenge in the field of CNF-reinforced composite research is to produce strong and transparent CNF/polymer composites that are sufficiently thick for use as load-bearing structural materials. In this study, we successfully prepared millimeter-thick, transparent CNF/polymer composites using CNF xerogels, with high porosity (~70%) and high SSA (~350 m2 g−1), as a template for monomer impregnation. A methacrylate was used as the monomer and was cured by UV irradiation after impregnation into the CNF xerogels. The CNF xerogels effectively reinforced the methacrylate polymer matrix, resulting in an improvement in the flexural modulus (up to 546%) and a reduction in the CTE value (up to 78%) while maintaining the optical transparency of the matrix polymer. Interestingly, the composites exhibited flame retardancy at high CNF loading. These unique features highlight the applicability of CNF xerogels as a reinforcing template for producing multifunctional and load-bearing polymer composites.
- Published
- 2021
32. Estimating the Strength of Single Chitin Nanofibrils via Sonication-Induced Fragmentation
- Author
-
Tsuguyuki Saito, Yu Ogawa, Yu Bamba, Akira Isogai, and Lars Berglund
- Subjects
Loligo bleekeri ,Materials science ,Polymers and Plastics ,Sonication ,Nanofibers ,Chitin ,Bioengineering ,Nanotechnology ,02 engineering and technology ,Liquid medium ,010402 general chemistry ,01 natural sciences ,Biomaterials ,Crystallinity ,chemistry.chemical_compound ,Tensile Strength ,Ultimate tensile strength ,Microalgae ,Materials Chemistry ,Animals ,Tensile fracture ,Lamellibrachia satsuma ,Decapodiformes ,Water ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,Chemical engineering ,0210 nano-technology - Abstract
We report the mechanical strength of native chitin nanofibrils. Highly crystalline α-chitin nanofibrils were purified from filaments produced by a microalgae Phaeocystis globosa, and two types of β-chitin nanofibrils were purified from pens of a squid Loligo bleekeri and tubes of a tubeworm Lamellibrachia satsuma, with relatively low and high crystallinity, respectively. These chitin nanofibrils were fully dispersed in water. The strength of individualized nanofibrils was estimated using cavitation-induced tensile fracture of nanoscale filaments in a liquid medium. Both types of β-chitin nanofibrils exhibited similar strength values of approximately 3 GP; in contrast, the α-chitin nanofibrils exhibited a much lower strength value of 1.6 GPa. These strength estimates suggest that the tensile strength of chitin nanofibrils is governed by the molecular packing modes of chitin rather than their crystallinity.
- Published
- 2017
33. Green and Fire Resistant Nanocellulose/Hemicellulose/Clay Foams
- Author
-
Lilian Medina, Lars Berglund, Joby J. Kochumalayil, and Federico Carosio
- Subjects
Materials science ,Polymer science ,Mechanical Engineering ,foams ,montmorillonite ,Nanocellulose ,Xyloglucan ,chemistry.chemical_compound ,xyloglucan ,Montmorillonite ,chemistry ,Mechanics of Materials ,Hemicellulose ,flame retardancy ,nanocellulose - Published
- 2021
34. Sustainable Development of Hot-Pressed All-Lignocellulose Composites—Comparing Wood Fibers and Nanofibers
- Author
-
Tom Lindström, Lars Berglund, and Erfan Oliaei
- Subjects
biocomposite ,Materials science ,Yield (engineering) ,Polymers and Plastics ,cumulative energy demand (CED) ,Glass fiber ,Organic chemistry ,molded fiber ,Review ,mechanical properties ,Nanocellulose ,chemistry.chemical_compound ,QD241-441 ,Lignin ,lignin-containing wood fibers ,Fiber ,Composite material ,nanocellulose ,chemistry.chemical_classification ,nanofibrillar/microfibrillar lignocellulose ,General Chemistry ,Polymer ,sustainability ,chemistry ,Nanofiber ,Biocomposite ,unbleached kraft pulp - Abstract
Low-porosity materials based on hot-pressed wood fibers or nanocellulose fibrils (no polymer matrix) represent a new concept for eco-friendly materials with interesting mechanical properties. For the replacement of fossil-based materials, physical properties of wood fiber materials need to be improved. In addition, the carbon footprint and cumulative energy required to produce the material also needs to be reduced compared with fossil-based composites, e.g., glass fiber composites. Lignin-containing fibers and nanofibers are of high yield and special interest for development of more sustainable materials technologies. The present mini-review provides a short analysis of the potential. Different extraction routes of lignin-containing wood fibers are discussed, different processing methods, and the properties of resulting fiber materials. Comparisons are made with analogous lignin-containing nanofiber materials, where mechanical properties and eco-indicators are emphasized. Higher lignin content may promote eco-friendly attributes and improve interfiber or interfibril bonding in fiber materials, for improved mechanical performance.
- Published
- 2021
35. Bioinspired Interface Engineering for Moisture Resistance in Nacre-Mimetic Cellulose Nanofibrils/Clay Nanocomposites
- Author
-
Lars Berglund, Yeping Xu, Qi Zhou, Hu Tang, Shu Huang, Gerd Buntkowsky, and Kun Yao
- Subjects
Solid-state chemistry ,Materials science ,Nanocomposite ,Moisture ,02 engineering and technology ,Adhesion ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Nanocellulose ,chemistry.chemical_compound ,Montmorillonite ,chemistry ,Ultimate tensile strength ,General Materials Science ,Composite material ,Cellulose ,0210 nano-technology - Abstract
The interfacial adhesion design between "mortar" and "bricks" is essential for mechanical and barrier performance of nanocellulose-based nacre-mimetic nanocomposites, especially at high moisture conditions. To address this fundamental challenge, dopamine (DA) has been conjugated to cellulose nanofibrils (CNFs) and subsequently assembled with montmorillonite (MTM) to generate layered nanocomposite films inspired by the strong adhesion of mussel adhesive proteins to inorganic surfaces under water. The selective formation of catechol/metal ion chelation and hydrogen bonding at the interface between MTM platelets and CNFs bearing DA renders transparent films with strong mechanical properties, particularly at high humidity and in wet state. Increasing the amount of conjugated DA on CNFs results in nanocomposites with increased tensile strength and modulus, up to 57.4 MPa and 1.1 GPa, respectively, after the films are swollen in water. The nanocomposites also show excellent gas barrier properties at high relative humidity (95%), complementing the multifunctional property profile.
- Published
- 2017
36. Experimental evaluation of anisotropy in injection molded polypropylene/wood fiber biocomposites
- Author
-
Roberts Joffe, Farhan Ansari, Fabiola Vilaseca, L.A. Granda, and Lars Berglund
- Subjects
Polypropylene ,Materials science ,Pulp (paper) ,Modulus ,02 engineering and technology ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,medicine.disease_cause ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Flexural strength ,Mechanics of Materials ,Compounding ,Mold ,Ultimate tensile strength ,Ceramics and Composites ,engineering ,medicine ,Composite material ,0210 nano-technology ,Anisotropy - Abstract
Although the anisotropy of wood fibers is reasonably well established, the anisotropy of injection molded wood fiber composites is not well understood. This work focuses on chemo-thermomechanical pulp (CTMP) reinforced polypropylene (PP) composites. A kinetic mixer (Gelimat) is used for compounding CTMP/PP composites, followed by injection molding. Effects from processing induced orientation on mechanical properties are investigated. For this purpose, a film gate mold was designed to inject composites in the shape of plates so that specimens in different directions to the flow could be evaluated. Observations from tensile tests were complemented by performing flexural tests (in different directions) on discs cut from the injected plates. SEM was used to qualitatively observe the fiber orientation in the composites. At high fiber content, both modulus and tensile strength could differ by as much as 40% along the flow and transverse to the flow. The fiber orientation was strongly increased at the highest fiber content, as concluded from theoretical analysis.
- Published
- 2017
37. Swelling and dimensional stability of xyloglucan/montmorillonite nanocomposites in moist conditions from molecular dynamics simulations
- Author
-
Yaoquan Tu, Jakob Wohlert, Lars Berglund, Hans Ågren, Malin Bergenstråhle-Wohlert, and Yan Wang
- Subjects
Materials science ,General Computer Science ,Composite number ,General Physics and Astronomy ,02 engineering and technology ,010402 general chemistry ,complex mixtures ,01 natural sciences ,chemistry.chemical_compound ,medicine ,General Materials Science ,Hemicellulose ,Relative humidity ,Composite material ,Nanocomposite ,General Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Xyloglucan ,Computational Mathematics ,Montmorillonite ,chemistry ,Mechanics of Materials ,Swelling ,medicine.symptom ,Biocomposite ,0210 nano-technology - Abstract
Nacre-mimetic biocomposites made from the combination of montmorillonite clay and the hemicellulose xyloglucan give materials that retain much of their material properties even at high relative humidity. Here, a model composite system consisting of two clay platelets intercalated by xyloglucan oligomers was studied at different levels of hydration using molecular dynamics simulations, and compared to the pure clay. It was found that xyloglucan inhibits swelling of the clay at low water contents by promoting the formation of nano-sized voids that fill with water without affecting the material’s dimensions. At higher water contents the XG itself swells, but at the same time maintaining contact with both platelets across the gallery, thereby acting as a physical cross-linker in a manner similar to the role of XG in the plant cell wall.
- Published
- 2017
38. The Type and Amount of Dietary Fat Affect Plasma Factor VIIc, Fibrinogen, and PAI-1 in Healthy Individuals and Individuals at High Cardiovascular Disease Risk: 2 Randomized Controlled Trials
- Author
-
Penny M Kris-Etherton, Paul W Stewart, Henry N Ginsberg, Russell P Tracy, Michael Lefevre, Patricia J Elmer, Lars Berglund, Abby G Ershow, Thomas A Pearson, Rajasekhar Ramakrishnan, Stephen F Holleran, Barbara H Dennis, Catherine M Champagne, Wahida Karmally, Henry Ginsberg, Maliha Siddiqui, Niem-Tzu Chen, Steve Holleran, Colleen Johnson, Roberta Holeman, Karen Chirgwin, Kellye Stennett, Lencey Ganga, Tajsudeen Towolawai, Minnie Myers, Colleen Ngai, Nelson Fontenez, Jeff Jones, Carmen Rodriguez, Norma Useche, Paul S Roheim, Donna Ryan, Marlene Most, Catherine Champagne, Donald Williamson, Richard Tulley, Ricky Brock, Deonne Bodin, Betty Kennedy, Michelle Barkate, Elizabeth Foust, Deshoin York, Penny Kris-Etherton, Satya Jonnalagadda, Janice Derr, Abir Farhat-Wood, Vikkie Mustad, Kate Meaker, Edward Mills, Mary-Ann Tilley, Helen Smiciklas-Wright, Madeleine Sigman-Grant, Shaomei Yu, Jean-Xavier Guinard, Pamela Sechevich, C Channa Reddy, Andrea M Mastro, Allen D Cooper, Patricia Elmer, Aaron Folsom, Nancy Van Heel, Christine Wold, Kay Fritz, Joanne Slavin, David Jacobs, Barbara Dennis, Paul Stewart, C Davis, James Hosking, Nancy Anderson, Susan Blackwell, Lynn Martin, Hope Bryan, W Brian Stewart, Jeffrey Abolafia, Malachy Foley, Conroy Zien, Szu-Yun Leu, Marston Youngblood, Thomas Goodwin, Monica Miles, Jennifer Wehbie, Thomas Pearson, Roberta Reed, Russell Tracy, Elaine Cornell, Kent Stewart, Katherine Phillips, Bernestine McGee, Brenda Williams, Gary Beecher, Joanne Holden, Carol Davis, Abby Ershow, David Gordon, Michael Proschan, and Basil Rifkind
- Subjects
Adult ,Male ,medicine.medical_specialty ,Nutrition and Disease ,Medicine (miscellaneous) ,Plasma factor ,Fibrinogen ,law.invention ,chemistry.chemical_compound ,Young Adult ,Randomized controlled trial ,law ,Risk Factors ,Internal medicine ,Plasminogen Activator Inhibitor 1 ,medicine ,Humans ,Dietary fat ,Aged ,Hemostasis ,Nutrition and Dietetics ,business.industry ,food and beverages ,Carbohydrate ,Factor VII ,Middle Aged ,medicine.disease ,Dietary Fats ,Diet ,Endocrinology ,chemistry ,Gene Expression Regulation ,Cardiovascular Diseases ,Plasminogen activator inhibitor-1 ,Disease risk ,Female ,Metabolic syndrome ,business ,medicine.drug - Abstract
BACKGROUND: Factor VIIc, fibrinogen, and plasminogen activator inhibitor 1 (PAI-1) are cardiovascular disease (CVD) risk factors and are modulated, in part, by fat type and amount. OBJECTIVE: We evaluated fat type and amount on the primary outcomes: factor VIIc, fibrinogen, and PAI-1. METHODS: In the Dietary Effects on Lipoproteins and Thrombogenic Activity (DELTA) Trial, 2 controlled crossover feeding studies evaluated substituting carbohydrate or MUFAs for SFAs. Study 1: healthy participants (n = 103) were provided with (8 wk) an average American diet [AAD; designed to provide 37% of energy (%E) as fat, 16% SFA], a Step 1 diet (30%E fat, 9% SFA), and a diet low in SFA (Low-Sat; 26%E fat, 5% SFA). Study 2: participants (n = 85) at risk for CVD and metabolic syndrome (MetSyn) were provided with (7 wk) an AAD, a step 1 diet, and a high-MUFA diet (designed to provide 37%E fat, 8% SFA, 22% MUFA). RESULTS: Study 1: compared with AAD, the Step 1 and Low-Sat diets decreased mean factor VIIc by 1.8% and 2.6% (overall P = 0.0001), increased mean fibrinogen by 1.2% and 2.8% (P = 0.0141), and increased mean square root PAI-1 by 0.0% and 6.0% (P = 0.0037), respectively. Study 2: compared with AAD, the Step 1 and high-MUFA diets decreased mean factor VIIc by 4.1% and 3.2% (overall P
- Published
- 2019
39. Statins and Lp(a): The plot thickens
- Author
-
Lars Berglund and Byambaa Enkhmaa
- Subjects
Molecular Weight ,chemistry.chemical_compound ,Animal science ,Phenotype ,chemistry ,business.industry ,Cholesterol ,Medicine ,Hydroxymethylglutaryl-CoA Reductase Inhibitors ,Cardiology and Cardiovascular Medicine ,business ,Apoprotein(a) ,Lipoprotein(a) - Published
- 2019
40. Nanostructure and Properties of Nacre-Inspired Clay/Cellulose Nanocomposites—Synchrotron X-ray Scattering Analysis
- Author
-
Kazuho Daicho, Yoshiharu Nishiyama, Lilian Medina, Max Yan, Lars Berglund, Tsuguyuki Saito, Centre de Recherches sur les Macromolécules Végétales (CERMAV ), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Department of Anatomical Pathology, Prince of Wales Hospital, Royal Institute of Technology, and Royal Institute of Technology [Stockholm] (KTH )
- Subjects
Materials science ,Nanostructure ,Polymers and Plastics ,Optical transmittance ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,law.invention ,[SPI.MAT]Engineering Sciences [physics]/Materials ,Inorganic Chemistry ,chemistry.chemical_compound ,law ,[CHIM.ANAL]Chemical Sciences/Analytical chemistry ,Materials Chemistry ,[CHIM.CRIS]Chemical Sciences/Cristallography ,[CHIM]Chemical Sciences ,Cellulose ,ComputingMilieux_MISCELLANEOUS ,Nanocomposite ,Scattering ,Organic Chemistry ,X-ray ,[CHIM.MATE]Chemical Sciences/Material chemistry ,021001 nanoscience & nanotechnology ,Synchrotron ,0104 chemical sciences ,[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry ,[CHIM.POLY]Chemical Sciences/Polymers ,chemistry ,Chemical engineering ,Gas barrier ,0210 nano-technology ,[SDV.AEN]Life Sciences [q-bio]/Food and Nutrition - Abstract
Nacre-inspired clay nanocomposites have excellent mechanical properties, combined with optical transmittance, gas barrier properties, and fire retardancy, but the mechanical properties are still be ...
- Published
- 2019
41. Nanocellulose films with multiple functional nanoparticles in confined spatial distribution
- Author
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Erik Jungstedt, David C. Malaspina, Anna Roig, Jordi Faraudo, Soledad Roig-Sanchez, Irene Anton-Sales, Anna Laromaine, Lars Berglund, Ministerio de Ciencia, Innovación y Universidades (España), Generalitat de Catalunya, European Commission, Centro de Supercomputación de Galicia, Wallenberg Wood Science Center, Consejo Superior de Investigaciones Científicas (España), Roig Sánchez, Soledad, Anton Sales, Irene, Malaspina, David C., Faraudo, Jordi, Berglund, Lars A., Laromaine, Anna, Roig Serra, Anna, Roig Sánchez, Soledad [0000-0002-7474-3769], Anton Sales, Irene [0000-0003-3511-2574], Malaspina, David C.[0000-0002-5420-9534], Faraudo, Jordi [0000-0002-6315-4993], Berglund, Lars A. [0000-0001-5818-2378], Laromaine, Anna [0000-0002-4764-0780], and Roig Serra, Anna [0000-0001-6464-7573]
- Subjects
chemistry.chemical_compound ,Nanocomposite ,Materials science ,chemistry ,Bacterial cellulose ,Volume fraction ,Nanoparticle ,General Materials Science ,Nanotechnology ,Cellulose ,Porosity ,Layer (electronics) ,Nanocellulose - Abstract
Industries, governments and consumers increasingly request sustainable resources and greener routes for the integration of advanced functional nanocomposites in products and devices. Among renewable biopolymers, cellulose deserves special consideration since it is the most abundant one. While inorganic nanoparticles add functional properties to a nanocomposite, a flexible and porous cellulosic support will facilitate the interaction of the nanoparticles with the surroundings, their handling and recycling. A significant challenge is to develop high strength, flexible nanobiocomposites controlling the nanoparticle properties, their volume fraction and their topographic distribution within the scaffold. A new concept is presented here for multifunctional laminates where layers consist of bacterial cellulose fibrils decorated by inorganic nanoparticles. Each layer can provide a specific function using a different nanoparticle. As model systems, we have selected two metals (Au, Ag) and two semiconductors (TiO2 and Fe2O3). Energy-efficient microwave-assisted synthetic routes have been used to in situ nucleate and grow the inorganic nanocrystals on the cellulose fibrils. Then, functionalized bacterial cellulose films can be arranged as laminates in a millefeuille construct simply by layering and drying the wet films at 60 °C. After drying, they perform as a single integrated and thicker film. Structural, functional and mechanical integrity of the laminates have been investigated. Molecular dynamics simulations were used to compute the surface adhesion energy between two cellulose fibrils and the results are discussed in light of the experimental peel-off data for the separation of the layers in the laminate., Authors acknowledge the financial support from the Spanish Ministry of Science, Innovation and Universities through the MAT2015-64442-R project, the ‘Severo Ochoa’ Programme for Centers of Excellence in R&D (SEV-2015-0496) and the PhD scholarships of S. R. (BES-2016-077533) and I. A. (BE-2016-076734) and the Generalitat de Catalunya for the 2017SGR765 project. D. C. M. is supported by the European Union's horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant agreement No. 6655919. We thank CESGA Supercomputing center for technical support and computer time at the supercomputer Finisterrae II. The Wallenberg Wood Science Center is acknowledged for funding of KTH activities., We acknowledge support of the publication fee by the CSIC Open Access Support Initiative through its Unit of Information Resources for Research (URICI)
- Published
- 2019
42. Recyclable nanocomposite foams of Poly(vinyl alcohol), clay and cellulose nanofibrils – Mechanical properties and flame retardancy
- Author
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Federico Carosio, Lilian Medina, and Lars Berglund
- Subjects
inorganic chemicals ,Solid-state chemistry ,Vinyl alcohol ,Materials science ,Cellulose degradation ,education ,02 engineering and technology ,Fire retardancy ,010402 general chemistry ,complex mixtures ,01 natural sciences ,Aerogels ,Biocomposites ,Freeze-drying ,Montmorillonite ,chemistry.chemical_compound ,cardiovascular diseases ,Cellulose ,Composite material ,Nanocomposite ,General Engineering ,Biomaterial ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,Ceramics and Composites ,lipids (amino acids, peptides, and proteins) ,0210 nano-technology - Abstract
Foam-like clay-nanocellulose hybrids are of great interest as load-bearing structural foams with excellent fire retardancy, due to unique effects from clay on thermal cellulose degradation. For the ...
- Published
- 2019
43. Nanocomposites from Clay, Cellulose Nanofibrils, and Epoxy with Improved Moisture Stability for Coatings and Semistructural Applications
- Author
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Farhan Ansari, Lilian Medina, Federico Carosio, Michaela Salajkova, and Lars Berglund
- Subjects
Nanocomposite ,Materials science ,biocomposite ,humidity ,Epoxy ,montmorillonite ,Nanocellulose ,chemistry.chemical_compound ,Montmorillonite ,chemistry ,visual_art ,nanocellulose ,mechanical ,Ultimate tensile strength ,visual_art.visual_art_medium ,General Materials Science ,Composite material ,Biocomposite ,Porosity ,Curing (chemistry) - Abstract
A new type of high reinforcement content clay–cellulose–thermoset nanocomposite is proposed, where epoxy precursors diffuse into a wet porous clay–nanocellulose mat, followed by curing. The processing concept was scaled to >200 μm thickness composites, the mechanical properties were high for nanocomposites, and the materials showed better tensile properties at 90% RH compared with typical nanocellulose materials. The nanostructure and phase distributions were studied using transmission electron microscopy; Young’s modulus, yield strength, ultimate strength, and ductility were determined as well as moisture sorption, fire retardancy, and oxygen barrier properties. Clay and cellulose contents were varied as well as the epoxy content. Epoxy had favorable effects on moisture stability and also improved reinforcement effects at low reinforcement content. A more homogeneous nano- and mesoscale epoxy distribution is still required for further property improvements. The materials constitute a new type of three-ph...
- Published
- 2019
44. Interface tailoring through covalent hydroxyl-epoxy bonds improves hygromechanical stability in nanocellulose materials
- Author
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Farhan Ansari, Lars Berglund, Mats Johansson, István Furó, and Erik L. Lindh
- Subjects
Materials science ,Chemical substance ,General Engineering ,Surface hydration ,Nanotechnology ,02 engineering and technology ,Epoxy ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Nanocellulose ,Nanomaterials ,chemistry.chemical_compound ,chemistry ,Covalent bond ,visual_art ,Ceramics and Composites ,visual_art.visual_art_medium ,Composite material ,Cellulose ,0210 nano-technology ,Science, technology and society - Abstract
Wide-spread use of cellulose nanofibril (CNF) biocomposites and nanomaterials is limited by CNF moisture sensitivity due to surface hydration. We report on a versatile and scalable interface tailor ...
- Published
- 2016
45. Mechanical performance and architecture of biocomposite honeycombs and foams from core–shell holocellulose nanofibers
- Author
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Lars Berglund, Fredrik Berthold, Lilian Medina, and Kasinee Prakobna
- Subjects
Nanocomposite ,Materials science ,Core (manufacturing) ,02 engineering and technology ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Surface coating ,chemistry ,Coating ,Mechanics of Materials ,Nanofiber ,Ceramics and Composites ,engineering ,Hemicellulose ,Biocomposite ,Cellulose ,Composite material ,0210 nano-technology - Abstract
CNFs (cellulose nanofibers) based on holocellulose have a pure cellulose fibril core, with a hemicellulose coating. The diameter is only around 6–8 nm and the hemicellulose surface coating has anio ...
- Published
- 2016
46. The unresolved mystery of high-density lipoprotein: time for a paradigm shift?
- Author
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Byambaa Enkhmaa, Lars Berglund, and Erdembileg Anuurad
- Subjects
0301 basic medicine ,business.industry ,Biochemistry (medical) ,Public Health, Environmental and Occupational Health ,General Medicine ,Astrophysics ,030204 cardiovascular system & hematology ,03 medical and health sciences ,chemistry.chemical_compound ,030104 developmental biology ,0302 clinical medicine ,High-density lipoprotein ,chemistry ,Physiology (medical) ,Paradigm shift ,Humans ,Medicine ,Lipoproteins, HDL ,business ,Triglycerides - Published
- 2016
47. Role of hydrogen bonding in cellulose deformation: the leverage effect analyzed by molecular modeling
- Author
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Cyrus Djahedi, Malin Bergenstråhle-Wohlert, Lars Berglund, and Jakob Wohlert
- Subjects
Physics::Biological Physics ,Materials science ,Polymers and Plastics ,Molecular model ,Hydrogen bond ,Leverage effect ,technology, industry, and agriculture ,02 engineering and technology ,Deformation (meteorology) ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Molecular dynamics ,Crystallography ,chemistry.chemical_compound ,stomatognathic system ,Chemical engineering ,chemistry ,Bioorganic chemistry ,Physics::Atomic Physics ,Physics::Chemical Physics ,Cellulose ,0210 nano-technology - Abstract
Role of hydrogen bonding in cellulose deformation : the leverage effect analyzed by molecular modeling
- Published
- 2016
48. Nanostructurally Controlled Hydrogel Based on Small‐Diameter Native Chitin Nanofibers: Preparation, Structure, and Properties
- Author
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Joby J. Kochumalayil, Qi Zhou, Nicholas Tchang Cervin, Ngesa Ezekiel Mushi, and Lars Berglund
- Subjects
Materials science ,Small diameter ,Compressive Strength ,General Chemical Engineering ,Chitin ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,chemistry.chemical_compound ,nanofibers ,Polymer chemistry ,Environmental Chemistry ,General Materials Science ,Porosity ,Full Paper ,Molecular Structure ,Hydrogels ,Full Papers ,021001 nanoscience & nanotechnology ,compression ,0104 chemical sciences ,General Energy ,Chemical engineering ,chemistry ,Nanofiber ,Self-healing hydrogels ,rheology ,hydrogel ,0210 nano-technology - Abstract
Chitin nanofibers of unique structure and properties can be obtained from crustacean and fishery waste. These chitin nanofibers have roughly 4 nm diameters, aspect ratios between 25–250, a high degree of acetylation and preserved crystallinity, and can be potentially applied in hydrogels. Hydrogels with a chitin nanofiber content of 0.4, 0.6, 0.8, 1.0, 2.0, and 3.0 wt % were successfully prepared. The methodology for preparation is new, environmentally friendly, and simple as gelation is induced by neutralization of the charged colloidal mixture, inducing precipitation and secondary bond interaction between nanofibers. Pore structure and pore size distributions of corresponding aerogels are characterized using auto‐porosimetry, revealing a substantial fraction of nanoscale pores. To the best of our knowledge, the values for storage (13 kPa at 3 wt %) and compression modulus (309 kPa at 2 wt %) are the highest reported for chitin nanofibers hydrogels.
- Published
- 2016
49. Distinct metabolism of apolipoproteins (a) and B-100 within plasma lipoprotein(a)
- Author
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Julian Lel, P. Hugh R. Barrett, Santica M. Marcovina, Margaret R. Diffenderfer, Gregory G. Dolnikowski, Lars Berglund, Stefania Lamon-Fava, and Ernst J. Schaefer
- Subjects
Male ,0301 basic medicine ,medicine.medical_specialty ,Very low-density lipoprotein ,Apolipoprotein B ,Endocrinology, Diabetes and Metabolism ,Clinical Sciences ,030204 cardiovascular system & hematology ,Apolipoproteins A ,Cardiovascular ,digestive system ,Endocrinology & Metabolism ,03 medical and health sciences ,0302 clinical medicine ,Endocrinology ,Leucine ,Internal medicine ,medicine ,Humans ,Dyslipidemias ,Hypertriglyceridemia ,biology ,Chemistry ,PCSK9 ,nutritional and metabolic diseases ,Metabolism ,Lipoprotein(a) ,Middle Aged ,Atherosclerosis ,medicine.disease ,Lipids ,Kinetics ,030104 developmental biology ,Biochemistry ,Apolipoprotein B-100 ,biology.protein ,Fed state ,lipids (amino acids, peptides, and proteins) ,Lipoprotein - Abstract
ObjectivesLipoprotein(a) [Lp(a)] is mainly similar in composition to LDL, but differs in having apolipoprotein (apo) (a) covalently linked to apoB-100. Our purpose was to examine the individual metabolism of apo(a) and apoB-100 within plasma Lp(a).Materials and methodsThe kinetics of apo(a) and apoB-100 in plasma Lp(a) were assessed in four men with dyslipidemia [Lp(a) concentration: 8.9-124.7nmol/L]. All subjects received a primed constant infusion of [5,5,5-(2)H3] L-leucine while in the constantly fed state. Lp(a) was immunoprecipitated directly from whole plasma; apo(a) and apoB-100 were separated by gel electrophoresis; and isotopic enrichment was determined by gas chromatography/mass spectrometry.ResultsMulticompartmental modeling analysis indicated that the median fractional catabolic rates of apo(a) and apoB-100 within Lp(a) were significantly different at 0.104 and 0.263 pools/day, respectively (P=0.04). The median Lp(a) apo(a) production rate at 0.248nmol/kg·day(-1) was significantly lower than that of Lp(a) apoB-100 at 0.514nmol/kg·day(-1) (P=0.03).ConclusionOur data indicate that apo(a) has a plasma residence time (11days) that is more than twice as long as that of apoB-100 (4days) within Lp(a), supporting the concept that apo(a) and apoB-100 within plasma Lp(a) are not catabolized from the bloodstream as a unit in humans in the fed state.
- Published
- 2016
50. Optically Transparent Wood from a Nanoporous Cellulosic Template: Combining Functional and Structural Performance
- Author
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Lars Berglund, Yuanyuan Li, Shun Yu, Min Yan, and Qiliang Fu
- Subjects
Materials science ,Optical Phenomena ,Polymers and Plastics ,Bioengineering ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,Lignin ,complex mixtures ,01 natural sciences ,law.invention ,Biomaterials ,chemistry.chemical_compound ,Cell Wall ,law ,Solar cell ,Materials Chemistry ,Transmittance ,Methyl methacrylate ,Cellulose ,Mechanical Phenomena ,Nanoporous ,technology, industry, and agriculture ,Optical Devices ,021001 nanoscience & nanotechnology ,Wood ,0104 chemical sciences ,Refractometry ,Cellulose fiber ,chemistry ,Chemical engineering ,Volume fraction ,0210 nano-technology - Abstract
Optically transparent wood (TW) with transmittance as high as 85% and haze of 71% was obtained using a delignified nanoporous wood template. The template was prepared by removing the light-absorbing lignin component, creating nanoporosity in the wood cell wall. Transparent wood was prepared by successful impregnation of lumen and the nanoscale cellulose fiber network in the cell wall with refractive-index-matched prepolymerized methyl methacrylate (MMA). During the process, the hierarchical wood structure was preserved. Optical properties of TW are tunable by changing the cellulose volume fraction. The synergy between wood and PMMA was observed for mechanical properties. Lightweight and strong transparent wood is a potential candidate for lightweight low-cost, light-transmitting buildings and transparent solar cell windows.
- Published
- 2016
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