Amount Of Cellulose Nanofibers Research Articles

Cellulose reinforcement of plant-based protein hydrogels: Effects of cellulose nanofibers and nanocrystals on physicochemical properties

This study explored the impact of cellulose-derived fillers, cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs), on the microstructure and texture of potato protein hydrogels (20 wt% protein). Particle size analysis, surface charge analysis, and molecular docking simulations suggested that the cellulose nanofibers and nanocrystals acted as inactive fillers within the potato protein matrix. Texture profile analysis showed that incorporation of small amounts of CNFs (<1%) increased the gel strength (by up to 69%), but the addition of larger amounts decreased it, which was attributed to disruption of the protein network by aggregated nanofibers at higher concentrations. The incorporation of CNCs had a much smaller effect on the gel strength of the potato protein hydrogels, only increasing it by up to 15% at 2% CNC. Shearing the cellulose-reinforced hydrogels in a shear rheometer had little impact on their gel strength at lower filler concentrations (<2 wt%) but increased it at higher concentrations. Microscopy analysis showed that the cellulose fibers could be aligned at sufficiently high shearing rates, leading to a fibrous microstructure. This study provides valuable insights into the optimization of the properties of cellulose fillers for application in plant protein hydrogels. In particular, it suggests that they may be utilized in plant-based meat analogs to enhance their textural attributes and optimize their appearance.

Investigating mechanical properties and energy absorption of elastomeric polymer nanocomposites containing cellulose nanofibers in tensile, quasi-static compression, and high strain rate tests

In this study, mechanical properties and energy absorption of elastomeric nanocomposites reinforced with cellulose nanofibers are investigated from tensile, Quasi-static Compression (QSC), and Split-Hopkinson Pressure Bar (SHPB) tests. For this purpose, the design and preparation of rubber nanocomposites with different loadings of cellulose nanofibers (CNFs) were carried out, and the optimal cure temperature (T90) of the rubber compound containing cellulose nanofibers was determined from the rheometer test. In the continuation of this study, the effects of adding cellulose nanofibers on the tensile strength, elongation to break, and energy absorption of the proposed Nano-composites were investigated. The results showed that the nanocomposite containing 6 phr increases the ultimate strength and elastic modulus of 300% by 33.5% and 22.7%, respectively, compared to the control rubber (0 phr). Similarly, these numbers are about 10 and 65% for loading 12 phr cellulose nanofibers. From the results of the quasi-static compression test for different amounts of cellulose nanofibers at a strain rate of 50%, it was found that the lowest and highest compressive stress due to the resistance of elastomeric nanocomposites is related to the control sample (0 phr) and the 12 phr sample, respectively. Also, from high strain rate tests of Split Hopkinson Pressure Bar, it was found that the fracture mechanism of flexible composites containing cellulose nanofibers changes in response to a high-speed impact, and the samples respond to high-pressure impact with brittle fractures. It was also found that rubber nanocomposites reinforced with cellulose nanofibers are very sensitive to strain rates. As the strain rate increases, the energy absorption of rubber nanocomposites increases. The optimal loading (6 phr) of cellulose nanofibers in rubber compounds makes them suitable for energy absorption applications. Cellulosic nanofibers provide acceptable dispersion of nanomaterials through good interaction with natural rubber and lignin-carbon fillers. Therefore, through the physical interweaving of fillers with polymer chains, CNF provide better binding of polymer chains to improve properties.

High‐velocity impact behavior and quasi‐static indentation of new elastomeric nanocomposites reinforced with cellulose nanofibers and lignin powder

AbstractThe present study investigates the indentation resistance of elastomeric nanocomposites based on natural rubber with different amounts of cellulose nanofibers (CNFs) under quasi‐static indentation (QSI) and high‐velocity impact (HVI) tests. At first, the baking characteristics and hardness of the samples were checked. The results showed that with the increase in CNFs content, the hardness of the samples increases, and the optimal baking time decreases. A high‐quality final product is produced through good dispersion and acceptable physical bonding between the CNF filler and the rubber chain. Further, the results of quasi‐static indentation showed that the amount of energy absorption for optimal loading of 6 phr increased by 43% compared to a control sample (0 phr). Similarly, from the high‐speed impact results for optimal loading (6 phr), the ballistic limit and energy absorption values increased by 23.6 and 52.7%, respectively, compared to the control sample (0 phr). It was also observed for higher values (9,12 phr) that the glass transition temperature, Tg, effect significantly affected the fracture behavior of the samples due to the high‐speed impact. Finally, CNFs provide better bonding with polymer chains to improve properties through good interaction with natural rubber, making them suitable for energy absorption applications.Highlights New elastomeric nanocomposites reinforced with cellulose nanofibers were made. Increasing the amount of CNFs decreases the optimum curing temperature. The hardness of elastomeric nanocomposites is increased by cellulose nanofibers. The indentation properties of nanocomposites have increased significantly. The optimum value of 6‐phr increased the impact resistance of nanocomposites.

Progress on Materials Reinforcement using Mechanically Defibrillated Cellulose Nanofibers

Cellulose nanofibers (CNFs) are highly crystalline, fibrous materials with a high aspect ratio of long cellulose molecules linked together with strong hydrogen bonds. These long cellulose molecules are incorporated into hemicellulose and lignin, the cell walls of higher plants. The modulus of elasticity of CNF remains constant between −200 °C and +200 °C. However, the linear coefficient of thermal expansion of cellulose fibers was 0.17 ppm/K, which is comparable to that of quartz glass. Further, CNFs have a thermal conductivity in the same order of magnitude as glass. Therefore, they are promising next-generation fiber owing to the excellent mechanical and thermal properties, sustainability, and biodegradability of CNF. Most studies on using CNFs to increase strength have focused on polymer matrix composites, particularly biodegradable polymers. However, it is difficult to increase the strength of materials using CNFs due to the agglomeration of CNFs. Compared to other composite materials, the uniform dispersion of nanosized CNFs is crucial. This article reports that CNFs may behave not as reinforcing fibers but as cross-linking agents to strengthen the polymer when the amount of CNFs is very small in polymer matrix composites, and the addition of CNFs is also effective in strengthening silk yarn and Ti. The mechanical properties of the ceramic green bodies can be increased using CNFs as an auxiliary agent in ceramic slurry. Moreover, the fabrication of composite materials using CNFs is essential for expanding the CNFs applications.

Cellulose nanofibers/PVA blend polymeric beads containing in-situ prepared magnetic nanorods as dye pollutants adsorbents

Magnetic beads were developed from polyvinyl alcohol and different amounts of cellulose nanofibers (CNF) by in-situ preparation of iron oxide nanoparticles in an alkaline aqueous medium at room temperature. The CNF were isolated from wheat straw, whereas the magnetic nanoparticles (MNPs) precursors were simple iron salts. The complete characterization of all the obtained materials was conducted, and among some other outstanding results it showed that all the components were strongly interacting via hydrogen bonding, while the nano-rods and husks like MNPs were effectively acting as crosslinking dots. All the prepared materials had good magnetic responses, and they were able to remove not only cationic, but also anionic dye pollutants from aqueous model solutions.

Multi-technique investigation regarding the impact of cellulose nanofibers on ultra-high-performance concrete at the macroscopic and microscopic levels

Cellulose nanofibers (CNFs) are renewable building materials with excellent potential for development. In this paper, we present a multi-technique study of the properties of samples with CNF addition at the macroscopic and microscopic levels. The hydration kinetics, autogenous shrinkage, microstructure, mechanical properties, and durability of the samples were investigated. The results are as follows: (1) CNFs suppress early hydration and accelerate later hydration. (2) The autogenous shrinkage decreased considerably with an increase in added CNFs. (3) Thermogravimetric analysis revealed that as the CNFs content increased, the combined water and calcium hydroxide content increased. X-ray diffraction and attenuated total reflection–Fourier transform infrared experiments revealed the calcium hydroxide content in the hydration products was low. (4) SEM tests revealed fiber pull-out, hydration product attachment on the CNFs surface, and fiber pocket formation in specimens with 0.3% CNF. (5) A two-aspect effect of CNFs on compressive strength was observed, namely an increase followed by a decrease. The final strength change depends on the amount of CNFs added and the high strength of the CNFs. (6) The addition of 0.1% CNFs refined the pore structure and improved the electrical resistivity. When CNFs were added in excess, the porosity increased and the resistivity decreased.

Addition of Cellulose Nanofibers to Control Surface Roughness for Hydrophobic Ceramic Coatings.

Hydrophobic ceramic coatings are used for a variety of applications. Generally, hydrophobic coating surfaces are obtained by reducing the surface energy of the coating material or by forming a highly textured surface. Reducing the surface energy of the coating material requires additional costs and processing and changes the surface properties of the ceramic coating. In this study, we introduce a simple method to improve the hydrophobicity of ceramic coatings by implementing a textured surface without chemical modification of the surface. The ceramic coating solution was first prepared by adding cellulose nanofibers (CNFs) and then applied to a polypropylene (PP) substrate. The surface roughness increased as the amount of added CNFs increased, increasing the water contact angle of the surface. When the amount of CNFs added was corresponding to 10% of the solid content, the surface roughness average of the area was 43.8 μm. This is an increase of approximately 140% from 3.1 μm (the value of the surface roughness of the surface without added CNFs). In addition, the water contact angle of the coating with added CNF increased to 145.0°, which was 46% higher than that without the CNFs. The hydrophobicity of ceramic coatings with added CNFs was better because of changes in the surface topography. After coating and drying, the CNFs randomly accumulated inside the ceramic coating layer, forming a textured surface. Thus, hydrophobicity was improved by implementing a rugged ceramic surface without revealing the surface of the CNFs inside the ceramic layer.

Effect of laboratory-produced cellulose nanofiber as an additive on performance of asphalt binders and mixes

In recent years, major initiatives have been taken to replace non-renewable materials with environmentally friendly and sustainable ones. The present study was undertaken to apply a scalable process for laboratory production of Cellulose Nanofibers (CNF) and to evaluate feasibility of using the produced CNF as a sustainable plant-based asphalt additive to improve the mechanical properties and durability of asphalt pavements. To achieve this goal, CNF was produced in the laboratory by applying electrospinning technique. Structure, morphology, and the size distribution of the produced CNF were evaluated using Scan Electron Microscopy. Also, tensile strength tests in two perpendicular directions were conducted on lab-produced CNF. The effect of incorporating different amounts of CNF in three types of asphalt binders, namely PG 58-28, PG 64-34, and PG 70-28 on fracture energy and dynamic viscosity of binder blends were evaluated by conducting Izod impact and rotational viscometer tests, respectively. Additionally, effect of CNF dosage in binder on its adhesion and moisture-induced debonding potential with aggregates of three different mineralogy was evaluated by conducting binder bond strength test. Furthermore, effect of incorporating CNF in asphalt mixes on their cracking, rutting, and moisture-induced damage potential was evaluated by conducting semicircular bend, Hamburg wheel tracking, and tensile strength ratio tests, respectively. From the tests conducted on asphalt binders and mixes, it was concluded that, incorporation of CNF resulted in an overall improvement in binder-aggregates adhesion, an asphalt binder with a higher fracture energy and dynamic viscosity, and an asphalt mix with a higher resistance to rutting, cracking, and moisture-induced damage.

Functionality of Cellulose Nanofiber as Bio-Based Nucleating Agent and Nano-Reinforcement Material to Enhance Crystallization and Mechanical Properties of Polylactic Acid Nanocomposite.

Polylactic acid (PLA), a potential alternative material for single use plastics, generally portrays a slow crystallization rate during melt-processing. The use of a nanomaterial such as cellulose nanofibers (CNF) may affect the crystallization rate by acting as a nucleating agent. CNF at a certain wt.% has been evidenced as a good reinforcement material for PLA; nevertheless, there is a lack of information on the correlation between the amount of CNF in PLA that promotes its functionality as reinforcement material, and its effect on PLA nucleation for improving the crystallization rate. This work investigated the nucleation effect of PLA incorporated with CNF at different fiber loading (1–6 wt.%) through an isothermal and non-isothermal crystallization kinetics study using differential scanning calorimetry (DSC) analysis. Mechanical properties of the PLA/CNF nanocomposites were also investigated. PLA/CNF3 exhibited the highest crystallization onset temperature and enthalpy among all the PLA/CNF nanocomposites. PLA/CNF3 also had the highest crystallinity of 44.2% with an almost 95% increment compared to neat PLA. The highest crystallization rate of 0.716 min–1 was achieved when PLA/CNF3 was isothermally melt crystallized at 100 °C. The crystallization rate was 65-fold higher as compared to the neat PLA (0.011 min–1). At CNF content higher than 3 wt.%, the crystallization rate decreased, suggesting the occurrence of agglomeration at higher CNF loading as evidenced by the FESEM micrographs. In contrast to the tensile properties, the highest tensile strength and Young’s modulus were recorded by PLA/CNF4 at 76.1 MPa and 3.3 GPa, respectively. These values were, however, not much different compared to PLA/CNF3 (74.1 MPa and 3.3 GPa), suggesting that CNF at 3 wt.% can be used to improve both the crystallization rate and the mechanical properties. Results obtained from this study revealed the dual function of CNF in PLA nanocomposite, namely as nucleating agent and reinforcement material. Being an organic and biodegradable material, CNF has an increased advantage for use in PLA as compared to non-biodegradable material and is foreseen to enhance the potential use of PLA in single use plastics applications.

Tensile properties of talc/polypropylene composites containing small amounts of cellulose nanofibers with different fiber length

Tensile properties of talc/polypropylene composites containing small amounts of cellulose nanofibers with different fiber length

Tensile properties of shape-controlled talc/polypropylene composites containing small amounts of cellulose nanofibers

Tensile properties of shape-controlled talc/polypropylene composites containing small amounts of cellulose nanofibers

Multiphase calcium alginate membrane composited with cellulose nanofibers for selective mass transfer

A multiphase calcium alginate membrane composited with cellulose nanofibers (CNF) was successfully prepared by using the method. The maximum stress and strain, water content, water permeability, and mass transfer characteristics were examined according to the addition ratio of CNF. Increasing of the amount of CNF enhanced the maximum stress and reduced the maximum strain, thereby suggesting that CNF impart flexibility and stiffness to the composite membrane. The CNF in the calcium alginate noticeably increased the water flux at the same pressure. The permeability of the composite of the CNF membrane was higher. The effective diffusion coefficient dramatically decreased 2.5 × 103 times when the molecular weight increased ten-fold (from 60 to 604 Da). Moreover, stronger dependency was observed in the CNF composite membrane. The morphology of the cross-section of the membrane was observed using scanning electron microscopy. The appearance of the CNF composite membrane became rougher when the amount of CNF increased.

Enhancing packaging board properties using micro- and nanofibers prepared from recycled board

In this study, cellulose microfibers and cellulose nanofibers (CNF) prepared from recycled boxboard pulp using a mechanical fine friction grinder were used as reinforcements in a board sheet. Micro- and nanofibers manufactured by mechanical grinding have typically broad particle size distribution, and they can contain both micro- and nano-sized fibrils. Deep eutectic solvent of choline chloride and urea was used as a non-hydrolytic pretreatment medium for the CNF, and reference CNF were used without any chemical pretreatment. The CNF were ground using three grinding levels (grinding time) and their dosage in the board varied from 2 to 6 wt%. The results indicate that the board properties could be tailored to obtain a balance between the processability and quality of the products by adjusting the amount of CNF that was added (2–6 wt%). A preliminary cost assessment indicated that the most economical way to enhance the board strength properties was to add around 4% of CNF with a moderate grinding level (i.e., grinding energy of 3–4 kWh/kg). Overall, the strength properties of the manufactured board sheets improved by several dozen percentages when CNF was used as the reinforcement.

Biodegradable composites of recycled thermoplastic starch and sawdust: the effect of cellulose nanofibers, nanoclay and temperature

Studies were performed on the effects of small amounts of cellulose nanofibers and nanoclay particles on mechanical, physical and morphological properties of biodegradable composites of recycled thermoplastic starch biopolymer and regular mixed industrial sawdust of Iranian wood species including rush, walnut and hornbeam. To this aim, nanoparticles at 0, 3, and 5 wt% were added to the prepared biodegradable composites. Mechanical, thermal, water absorption and thickness swelling tests were performed according to their corresponding standards. In addition, to investigate the effects of working temperature on derived characteristics of the resulting composites, the selected mechanical tests were performed at various temperatures ranging from 23 to 80 °C. For validation of the results obtained from the physical tests, scanning electron microscopy was also utilized to examine the morphologies of the nanocomposites. The results showed that adding nanoparticles improved tensile modulus by 50%, tensile strength by 110%, flexural modulus by 115%, and flexural strength by 18%. Adding 5 wt% nanocellulose fibers showed better results than 3 wt% addition, while in the case of nanoclay, the trend was reverse. No significant change was observed for impact strength. Glass transition temperature was increased from 90 to 123 °C depending on the amount of nanoparticles. Water absorption and thickness swelling were reduced by around 20%. It was also observed that at elevated temperatures nanoparticles led to greater stability of the composite structure. From the results of this study it can be concluded that cellulose nanofibers and nanoclay particles can be successfully used for improving the mechanical and physical characteristics and performance of the biodegradable WPCs made of thermoplastic starch and industrial sawdust. Furthermore, since the effect of adding each of these nanoparticles on mechanical and physical performance of WPCs is different, the results of this study can be used to decide on selection of the type and amount of nanoparticles for fabrication of a product for a desired application.

Dual Functions of TEMPO-Oxidized Cellulose Nanofibers in Oil-in-Water Emulsions: A Pickering Emulsifier and a Unique Dispersion Stabilizer.

The emulsifying and dispersing mechanisms of oil-in-water emulsions stabilized by 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO)-oxidized cellulose nanofibers (CNFs) have been investigated. The emulsifying mechanism was studied by changing the oil/water interfacial tension from 8.5 to 53.3 mN/m using various types of oils. The results showed that the higher the oil/water interfacial tension, the greater is the amount of CNFs adsorbed at the oil/water interface, making the CNF-adsorbed oil-in-water emulsions thermodynamically more stable. Moreover, the amount of CNFs adsorbed on the surfaces of the oil droplets increased with increasing interfacial area. The dispersion stability of the oil droplets was dominated by the CNF concentration in the water phase. Above the critical concentration (0.15% w/w), the CNFs formed network structures in the water phase, and the emulsion was effectively stabilized against creaming. Emulsion formation and the CNF network structures in the emulsion were visualized by cryo-scanning electron microscopy.

In Situ Production and Application of Cellulose Nanofibers to Improve Recycled Paper Production.

The recycled paper and board industry needs to improve the quality of their products to meet customer demands. The refining process and strength additives are commonly used to increase mechanical properties. Interfiber bonding can also be improved using cellulose nanofibers (CNF). A circular economy approach in the industrial implementation of CNF can be addressed through the in situ production of CNF using side cellulose streams of the process as raw material, avoiding transportation costs and reducing industrial wastes. Furthermore, CNF fit for use can be produced for specific industrial applications.This study evaluates the feasibility of using two types of recycled fibers, simulating the broke streams of two paper machines producing newsprint and liner for cartonboard, to produce in situ CNF for direct application on the original pulps, old newsprint (ONP), and old corrugated container (OCC), and to reinforce the final products. The CNF were obtained by 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)-mediated oxidation and homogenization at 600 bar. Handsheets were prepared with disintegrated recycled pulp and different amounts of CNF using a conventional three-component retention system. Results show that 3 wt.% of CNF produced with 10 mmol of NaClO per gram of dry pulp improve tensile index of ONP ~30%. For OCC, the same treatment and CNF dose increase tensile index above 60%. In both cases, CNF cause a deterioration of drainage, but this effect is effectively counteracted by optimising the retention system.

Structural and mechanical properties of fibrous poly (caprolactone)/gelatin nanocomposite incorporated with cellulose nanofibers

To proceed with the electrospun poly (caprolactone) (PCL)/gelatin (Gel) combinations, the current research was aimed to explore the incorporation of cellulose nanofibers (CNF) into the PCL/Gel blends for the first time. Accordingly, various amounts of CNF were added to different ratios of PCL/Gel, and the corresponding electrospun nanocomposites were examined. Observing morphology via scanning electron microscopy proved, unexpectedly, increasing fibers diameter upon CNF addition into PCL/Gel blends. Mechanical analysis in tensile mode revealed more brittle electrospun PCL/Gel when more Gel was included into the blend due to higher Young’s modulus and lower ultimate tensile strength and strain at break. Addition of various contents of CNF led to strain reduction while displayed a summit-like curve for UTS and modulus, where registered maximum values at 2 wt% CNF for all PCL/Gel/CNF. Among the electrospun nanocomposites the highest UTS (3.24 ± 0.22 MPa) belonged to sample including 70 wt% PCL, 30 wt% Gel, and 2 wt% CNF (P70/2CNF), while P30/2CNF recorded maximum modulus (93.89 ± 10.44 MPa). The wide-angle X-ray scattering confirmed increase in PCL crystallinity upon CNF incorporation Furthermore, the presence of PCL, Gel, and CNF in electrospun composites was confirmed with Fourier transform infrared spectroscopy. Degradability of electrospun nanocomposites was carried out in PBS solution, which showed that CNF addition reduced degradation rate of PCL/Gel blends.

Tannin-furanic resin foam reinforced with cellulose nanofibers (CNF)

In this study, tannin-furanic resin was directly mixed with different percentages of cellulose nanofibers (CNF) (0.1% and 0.2% based on the solid content of tannin resin) to obtain tannin-furanic resin reinforced foam. The microscopic investigation showed that the CNF were dispersed homogeneously in the tannin-furanic resin aqueous solution. The impact of CNF addition on the properties of the tannin foam, such as the foaming process, foam density, cell morphology, and mechanical properties as well as the thermal insulation and flammability were studied. The results disclosed that tiny amounts of CNF in the foam formulation could improve the compressive strength of tannin-furanic resin foam especially with 0.2 wt% loading of CNF. The reinforced foams showed smaller pore size and faster foaming without significantly affecting the thermal and flammability properties.

Comparison of Mechanical Reinforcement Effects of Cellulose Nanofibers and Montmorillonite in Starch Composite

Both cellulose nanofibers (CNF) and montmorillonites (MMT) are nanoscale reinforcement fillers that have shown reinforcing effects in polymer nanocomposites. CNFs belong to one‐dimensional nanofibers while MMT is part of two‐dimensional clay platelets, which show difference in shape, size, and composition. This study systematically compares their morphology and dispersion properties in a corn starch (CS) matrix, interactions with the matrix, and the resulting reinforcing effects on the CS matrix. Transparent CS/CNF and CS/MMT nanocomposites comprising up to 7 wt% nanofillers are obtained via solution casting. Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), Scanning Electron Microscope (SEM), and tensile testing, thermogravimetry analysis (TGA), moisture uptake (Mu), and light transmittance (Tr) are used to examine the above‐mentioned properties of CS composites. It is found that the tensile properties, optical transparency, and water barrier properties of CS films are significantly improved whether adding a certain amount of CNF or MMT. However, the tensile strength increment of CS composites reinforced with CNF is slightly higher than that of MMT‐reinforced CS composites due to higher aspect ratio of CNF. From the results, it can be concluded that CNF is highly compatible with starch and can reinforce the starch phase efficiently to prepare green nanocomposite films.

Reinforcing Mechanical Strength of Electrospun Chitosan Nanofibrous Scaffold Using Cellulose Nanofibers

In this study, cellulose nanofibers (CNF) was used as a reinforcing material to improve mechanichal strenght of chitosan nanofibrous scaffold. Chitosan scaffolds with different amount of CNF ranging 5.0-20.0 Wt.% were fabricated by adding CNF to chitosan solutions before electrospinning. Both the tensile strength and tensile modulus of the scaffolds were increased as a result of CNF addition. An increase of 4.3 fold (from 2.9±0/02 to 12.7±0/4 MPa) in tensile strength and 4.04 fold (from 86.5±1.7 to 349.5±19.4 P) in Young's modulus were observed after addition of 15 wt. % CNF. The microscopy studies showed that the diameter of the electrospun fibers decreased with the addition of CNF. The diameter decreased from 175± 7 nm to 100±29 nm when 15 wt% CNF were added. Evaluation of cell adhesion by SEM showed that fibroblast cells not only can attachment on the surface of NFC reinforced scaffolds but also can infilterate inside the scaffolds. In addition, the nanocomposite schaffols dose not show any cytotoxic effect using MTT assay.