Cellulose Nanofibrils Research Articles

Constructing gradient reflection and scattering porous framework in composite aerogels for enhanced microwave absorption

Developing high-performance microwave absorption (MA) materials becomes an urgent concern in the field of electromagnetic protection. Constructing porous framework is an efficient approach to MA owing to the abilities of adjusting impedance matching and providing more reflection and scattering paths for electromagnetic waves. Herein, a cellulose nanofibril (CNF)/honeycomb-like carbon-shell encapsulated FeCoNi@C/carbon nanotube (CNT) composite aerogel was fabricated via a facile freeze-drying method. The super-lightweight composites showed a distinctive gradient structure for reflection and scattering inside aerogel pores, micrometer small pores, and nano-fillers on the pore walls. The composite aerogel showed an ideal minimum reflection loss (RLmin) of −43.6 dB and remarkable adjustable effective absorption bandwidth (EAB) of 12.18 GHz due to good impedance matching, unique gradient porous structure, and synergies of multiple loss mechanisms. Therefore, this work will provide a viable strategy to improve the MA capability of absorbers by taking full advantage of constructing gradient reflection and scattering porous structure.

Performance characterization of plywood panels bonded with melamine-urea-formaldehyde resin and cellulose nanofibril/borax as an additive

In this study, different loading levels of cellulose nanofibril and borax were added as reinforcement in melamine-urea-formaldehyde adhesive to enhance the performance properties of plywood panels as engineered wood composites. Physical properties (density, thickness swelling, water absorption, and moisture content), mechanical properties (modulus of rupture, modulus of elasticity, and bonding strength), and formaldehyde content were tested using relevant standards. The results showed that cellulose nanofibril and borax had a synergistic effect, resulting in improved physico-mechanical properties. The best results were obtained by combining 3 % cellulose nanofibril and borax. It was determined that the combination of cellulose nanofibril and borax reinforcement resulted in a significant improvement of around 15 % in the thickness swelling, water absorption, and moisture content of plywood panels. The combination of cellulose nanofibril and borax reinforcing resulted in a significant increase of around 26 % in the modulus of rupture and modulus of elasticity of plywood panels, with a bonding strength of around 47 %. The reinforcement technique did result in a 34 % decrease in free formaldehyde content. As a consequence, cellulose nanofibril and borax can be used as effective additives in the production of plywood panels to enhance their performance properties.

On rheological properties of disc-shaped cellulose nanocrystals

The rheological properties of a substance depend greatly on its morphology, and rod-shaped cellulose nanocrystals (RCNCs) and cellulose nanofibrils (CNFs) have been extensively studied for their rheological properties. Nevertheless, the rheological properties of disc-shaped cellulose nanocrystals (DCNCs) with crystalline allomorph II derived from mercerized cellulose remain unknown yet. This work investigated the DCNCs' rheological properties in depth using steady-shear and oscillation measurements. At the same concentration, DCNC's suspension viscosity is lower than that of RCNC; RCNC has an instinct viscosity of 258.2, while DCNC has 187.9. Comparing RCNC suspensions with cellulose nanorods, DCNC has a lower aspect ratio and exhibits a distinct steady shear behavior. Under polarized film, DCNC suspension cannot self-assemble into chiral or liquid crystal phases, and with increasing concentrations, the system transitions from an isotropic phase to a gel phase. Oscillation sweeps demonstrate that the gel transition occurs at 7 %–8 %. Based on thixotropic recovery sweep outcomes, the high-stress oscillations enhance the network structure of DCNC suspensions, which is significantly different from that of RCNC suspensions. Results demonstrate the unique properties of DCNC, highlighting its application as a rheological modifier.

Integrating ball milling assisted enzymatic hydrolysis of bamboo cellulose for controllable production of xylo-oligosaccharides, monosaccharides and cellulose nanofibrils

Green bioconversion technology has been regarded as a fundamental solution to energy challenges and environmental issues. During bioconversion, a combination of mechanical and enzymatic treatment on lignocellulosic biomass can not only conformity with environmental concepts but also enable efficient conversion. In this study, a ball milling assisted enzymatic treatment was applied for full utilization of bamboo cellulose. In addition to the production of soluble saccharides, the residues that remained after enzymatic hydrolysis were collected for producing high-quality nanocellulose. Ball milling efficiently broke the hydrogen bonding interactions between glucan chains thus promoting the following xylanase and cellulase conversion. The highest Xylo-oligosaccharides (XOS) yield reached 21.6%. Meanwhile, xylanase facilitated cellulase hydrolysis by separation of hemicellulose on cellulose. With a low commercial cellulase loading of 5 FPU/g glucan, a maximum yield of 76.6% glucose and 53.3% xylose was reached. Finally, nanocellulose was extracted from the enzymatic hydrolyzate residue with a minimum width of 3.5 nm and an average size of 294.8 nm. The present study proposed an efficient combination of mechanical treatment assisted enzymatic digestion, which is not only environmentally friendly but also allows for complete bioconversion of bamboo cellulose.

Degraded Paper: Stabilization and Strengthening Through Nanocellulose Application

ABSTRACT Cellulose nanomaterials are a promising material for the stabilization of degraded paper, since their characteristics in composition, structure and physical properties are close to those of cellulose. Two types of nanocellulose were tested regarding their performance in stabilizing fragile papers: cellulose nanofibrils (CNF) and cellulose nanocrystals (CNC). The suspensions were applied to a pure cellulose paper and historical newspaper. The study included optical and microscopic characterization, determination of pH, conductivity, and rheology as well as measurement of changes in tensile strength after treatment. The results showed that the pH, as well as the optical and haptic properties, were not altered after treatment. A 50% increase in paper’s tensile strength is achieved with 3% CNC applied on the paper. In addition, fluorescence microscopy demonstrated that, due to their nanoscale dimension, the suspensions can reinforce the surface but also fully penetrate the paper matrix achieving therefore an overall stabilization.

Production and Characterization of Cellulose Nanofibrils from Cotton Noil Waste

HighlightsCotton noil is a waste short fiber from the cotton yarn industry.Cellulose nanofibrils were produced by ball-milling and high-pressure homogenization processes.The width of nanofibrils ranged from 50 to 70 nm, with about 80% crystallinity index.The 5% CNF had a tensile strength of about 25 MPa and can be used as a reinforcing material.Abstract. Cellulose nanofibrils (CNF), the nanostructured cellulose, are promising nanomaterials for bio-based barrier coating and packaging applications. In this study, we investigated the production of cellulose nanofibrils from cotton noil, a waste short-fiber from the cotton yarn industry. The cotton noil fibers were subjected to ball milling for 10 min and dispersed in water to prepare slurries with three different concentrations (1%, 5%, and 10% w/v). Then, the slurry was passed through a high-pressure homogenizer at 700 bar pressure for 14 cycles or until the fibers were fibrillated into CNF hydrogels. The CNF with 1% and 5% concentrations had an average width of 70 and 52 nm, respectively, while the 10% CNF concentration had a mix of both nanofibrils and microfibrils due to inconsistent fibrillation. Fourier Transform InfraRed (FTIR) spectroscopy and X-ray diffraction techniques on the isolated CNFs demonstrated that the manufacturing process did not affect the cellulose molecular structure or crystallinity. The tensile strength of CNF from 5% concentration was about 25 MPa. This simple manufacturing method can be applied to utilize cotton noil fibers to produce CNF for various applications. Keywords: Ball milling, Cellulose nanofibrils, Cotton noil, Homogenization, Tensile strength.

Sprayed water-based lignin colloidal nanoparticle-cellulose nanofibril hybrid films with UV-blocking ability.

In the context of global climate change, the demand for new functional materials that are sustainable and environmentally friendly is rapidly increasing. Cellulose and lignin are the two most abundant raw materials in nature, and are ideal components for functional materials. The hydrophilic interface and easy film-forming properties of cellulose nanofibrils make them excellent candidates for natural biopolymer templates and network structures. Lignin is a natural UV-shielding material, as it contains a large number of phenolic groups. In this work, we have applied two routes for spray deposition of hybrid films with different laminar structures using surface-charged cellulose nanofibrils and water-based colloidal lignin particles. As the first route, we prepare stacked colloidal lignin particles and cellulose nanofibrils hybrid film through a layer-by-layer deposition. As the second route, we spray-deposite premixed colloidal lignin particles and cellulose nanofibrils dispersion to prepare a mixed hybrid film. We find that cellulose nanofibrils act as a directing agent to dominate the arrangement of the colloidal lignin particles in a mixed system. Additionally, cellulose nanofibrils eliminate the agglomerations and thus increase the visible light transparency while retaining the UV shielding ability. Our research on these colloidal lignin and cellulose nanofibril hybrid films provides a fundamental understanding of using colloidal lignin nanoparticles as functional material on porous cellulose-based materials, for example on fabrics.

Engineering strong man-made cellulosic fibers: a review of the wet spinning process based on cellulose nanofibrils.

With the goal of sustainable development, manufacturing continuous high-performance fibers based on sustainable resources is an emerging research direction. However, compared to traditional synthetic fibers, plant fibers have limited length/diameter and uncontrollable natural defects, while regenerated cellulose fibers such as viscose and Lyocell suffer from inferior mechanical properties. Wet-spun fibers based on nanocelluloses especially cellulose nanofibrils (CNFs) offer superior mechanical performance since CNFs are the fundamental high-performance building blocks of plant cell walls. This review aims to summarize the progress of making CNF wet-spun fibers, emphasizing on the whole wet spinning process including spinning suspension preparation, spinning, coagulation, washing, drying and post-stretching steps. By establishing the relationships between the nano-scale assembling structure and the macroscopic changes in the CNF dope from gels to dried fibers, effective methods and strategies to improve the mechanical properties of the final fibers are analyzed and proposed. Based on this, the opportunities and challenges for potential industrial-scale production are discussed.

Propriedades no estado fresco e endurecido de compósitos cimentícios com a adição de celulose nanofibrilada

Abstract Evaluating the effects of nanomaterials in cementitious systems is paramount to projecting high-performance construction materials. However, the synthesis of some nanomaterials on a large scale and their toxicity may limit their application. In this context, nanofibrillated cellulose (NFC), a biodegradable and natural material stand out. Thus, this paper aims to study the influence of NFC on the fresh, hardened properties (compressive and flexural strengths) and mineralogy of cementitious systems. The results indicated that incorporating up 0.075 wt.% to CNF reduced the spread of cement pastes by up to 14.0%. A CNF content of 0.025 wt.% increased the 28-d compressive and flexural strengths by 22.0% and 25.0%, respectively, compared to the control sample. The X-ray diffraction (XRD) results indicate that higher NFC contents (>0.025 wt.%) resulted in lower intensity portlandite peaks after 7 days, which may show a lower hydration degree, especially concerning the plain cement paste. These results suggest that the NFC can affect the hydration of cementitious matrices at early ages; however, it did not significantly affect the hydration degree after 28 days of hydration.

Crude oil sorbent based on cellulose nanofibrils-methacrylate grafted copolymers

Hydrophobic composites of cellulose nanofibrils (CNF) with acrylic polymers are obtained by methyl methacrylate (MMA) and butyl methacrylate (BMA) polymerization in Pickering emulsion, stabilized with cellulose nanofibrils. Successful modification of CNF surface by grafting MMA or BMA was confirmed by infrared spectroscopy, gel permeation chromatography, and scanning electron microscopy. The obtained composites were also characterized by simultaneous thermal analysis and wetting contact angle measurement. Composites based on CNF exhibit good thermal and oil sorption properties.

Cellulose nanofibril-guided orienting response of supramolecular network enables superstretchable, robust, and antifatigue hydrogel

<p>Hydrogels featuring randomly networked matrix typically show poor mechanical strength owing to the weak interchain interactions of the matrix. Encouragingly, the stretchability and toughness of hydrogel materials along a certain direction were recently improved to an unprecedented level with the design of structured and oriented matrix, the realization of excellent and concurrently isotropic mechanical performance for hydrogels now become the next- research goal. Herein, a self-assembling process of poly(vinyl alcohol) (PVA) macromolecular chain and cellulose nanofibril (CNF) induced by the salting-out effect was reported, which allowed the formation of a strongly hydrogen-bonded PVA-CNF supramolecular matrix. The resulting hydrogel, in any direction, can show an ultra-high stretchability of 7,400% and a true tensile strength of 420 MPa through the orientation of the supramolecular matrix. The robustness of the supramolecular interaction between PVA and CNF was experimentally demonstrated by the fact that the hydrogel showed a high fracture energy (reaching up to 95.7 kJ m<sup>−2</sup>) and low notch sensitivity (fatigue threshold of 3,203 J m<sup>−2</sup>), even outperforming most state-of-the-art anisotropic hydrogels. These results highlight that constructing supramolecular interaction among various components of gel matrix holds great promise for the design of future gel materials with the extraordinary mechanical performance.</p>

Production of lignin containing cellulose nanofibrils (CNF) after enzymatic treatment of curl-induced, unbleached kraft pulps

Curling treatment of unbleached Kraft pulp fibers creates disordered cellulose, enhancing enzyme accessibility for fiber modification. This facilitates micro/nano-fibrillation, improving mechanical performance for potential functional applications.

Strengthening polylactic acid (PLA) composites with poly(methyl methacrylate)-functionalized cellulose nanofibrils created through grafting-through emulsion polymerization

Aqueous surfactant free emulsion grafting-through polymerization produced poly(methyl methacrylate) coated cellulose nanofibrils that retained microstructure and strengthened poly(lactic acid) composites.

Research progress on nanocellulose and its composite materials as orthopedic implant biomaterials

This review summarizes recent progress on nanocellulose and its composite materials as emerging biomaterials for orthopedic implant applications. The three main types of nanocellulose - cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs) and bacterial nanocellulose (BNC) possess exceptional mechanical properties exceeding traditional implant materials like metals, ceramics and polymers. Their high strength, stiffness, porosity, surface area, hydrophilicity and biocompatibility make nanocellulose well-suited as a scaffold material for bone regeneration. This review covers the fabrication of nanocellulose-based composites with ceramics and polymers to further enhance their mechanical performance and bioactivity. Various methods are utilized to develop nanocellulose implants and scaffolds with controlled architecture optimized for bone ingrowth. In vitro studies demonstrate nanocellulose supports stem cell osteogenic differentiation and growth. In vivo results in animal models show bone regeneration in critical sized defects, though challenges remain in vascularization. While further research is required to control degradation and scale up manufacturing, nanocellulose has strong potential to address limitations of current orthopedic implants as the next generation of high performance biomaterials. This review provides a comprehensive perspective on the state-of-the-art in nanocellulose materials for advanced orthopedic implants.

Hydrophobized lignin nanoparticle-stabilized Pickering foams: building blocks for sustainable lightweight porous materials

CTAB-hydrophobized lignin nanoparticles for durable Pickering foam formation with cellulose nanofibrils as templates for lightweight porous materials.

The influence of drying routes on the properties of anisotropic all-cellulose composite foams from post-consumer cotton clothing.

Biopolymer-based functional materials are essential for reducing the carbon footprint and providing high-quality lightweight materials suitable for packaging and thermal insulation. Here, cellulose nanocrystals (CNCs) were efficiently upcycled from post-consumer cotton clothing by TEMPO-mediated oxidation and HCl hydrolysis with a yield of 62% and combined with wood cellulose nanofibrils (CNFs) to produce anisotropic foams by unidirectional freeze-casting followed by freeze drying (FD) or supercritical-drying (SCD). Unidirectional freeze-casting resulted in foams with aligned macropores irrespective of the drying method, but the particle packing in the foam wall was significantly affected by how the ice was removed. The FD foams showed tightly packed and aligned CNC and CNF particles while the SCD foams displayed a more network-like structure in the foam walls. The SCD compared to FD foams had more pores smaller than 300 nm and higher specific surface area but they were more susceptible to moisture-induced shrinkage, especially at relative humidities (RH) > 50%. The FD and SCD foams displayed low radial thermal conductivity, and the FD foams displayed a higher mechanical strength and stiffness in compression in the direction of the aligned particles. Better understanding how drying influences the structural, thermal, mechanical and moisture-related properties of foams based on repurposed cotton is important for the development of sustainable nanostructured materials for various applications.

Collagen/functionalized cellulose nanofibril composite aerogels with pH-responsive characteristics for drug delivery system

In this work, carboxylated and amination modified cellulose nanofibrils (CNFs) were fabricated via the TEMPO catalytic oxidation system and diethylenetriamine, and collagen composite aerogels were fabricated through a simple self-assembly pretreatment and directional freeze-drying technology. Morphology analysis showed that the collagen composite aerogels had distinct layered-oriented double network structures after the self-assembly pretreatment. The intermolecular interactions between the collagen fibrils and functionalized CNFs (fCNFs) on the structures and properties of the composite aerogels were also examined through various characterization techniques. Water contact angle tests demonstrated the pH-responsive characteristics of the collagen/fCNF composite aerogels. Using 5-fluorouracil as the model drug, the pH-response mechanism was revealed. These results indicated that the collagen/fCNF composite aerogels exhibited excellent pH-responsive drug release capacities. Therefore, these pH-responsive collagen composite aerogels might have potential applications in industrial production in the biomedical, drug delivery, and tissue engineering fields.

Capacitive CO2 sensor made of aminated cellulose nanofibrils: development and optimization

This study introduces a novel capacitive CO2 sensor using aminated cellulose nanofibrils, offering enhanced sensitivity and selectivity.

Superhydrophobic foam combined with biomass-derived TENG based on upcycled coconut husk for efficient oil-water separation.

The ocean ecological environments are seriously affected by oil spilling and plastic-debris, preventing and significantly reducing marine pollution via using biocomposite production from natural fiber reinforcement is a more friendly way to deal with marine oil pollution. Herein, we upcycled coir-coconut into lignin and coconut shell into spherical TENG by a combination of dip-dry and chemical treatment and used the SiO2 nanoparticles together with cellulose nanofibrils to prepare serial sugar-templated, anisotropic and hybrid foams. The as-prepared lignin/SiO2 porous sponge (LSPS) with a hierarchical porous morphology and uniformly dispersed nanoparticles structure benefits from the advantages of biomass-based additives, which presents reversible large-strain deformation (50%) and high compressive strength (11.42 kpa). Notably, the LSPS was significantly more hydrophobic (WCA ≈150°) than pure silicone-based foams, and its selective absorbability can separate oil from water under continuous pumping. Meanwhile, the coconut husk was also upcycled as a spherical TENG shell by a combination of the nanofiber-enhanced polymer spherical oscillator (CESO), which possessed high triboelectric properties (Uoc = 272 V, Isc = 14.5 μA, Q = 70 nC) and was comparable to the plastic shell TENG at low frequency (1.6 Hz). The monolithic foam structure developed using this clean synthetic strategy holds considerable promise for new applications in sustainable petroleum contamination remediation.

Transcrystalline Polypropylene-Based Honeycomb Structures Spontaneously Induced on Amphiphilic Cellulose Nanofibrils Prepared by Aqueous Counter Collisio

Transcrystalline Polypropylene-Based Honeycomb Structures Spontaneously Induced on Amphiphilic Cellulose Nanofibrils Prepared by Aqueous Counter Collisio