Cellulose Nanofibers Content Research Articles

Viability of cellulose nanofibre powder and silica fume in self-compacting concrete rheology, hardened properties, and microstructure

This research investigated the influence of adding cellulose nanofiber (CNF) on the rheology and hardened properties of self-compacting concrete (SCC). The CNFs were produced from wastepaper through chemical treatment and added as 0.25%, 0.50%, 1%, 2%, and 3% by weight of cement in SCC. The results revealed that the increase in the content of CNF caused the decrease in slump flow diameter (SFD), and the lowest SFD of 600 mm was achieved at 2% CNF. In addition, the T50 flow and unit weight increased with the increase in the content of CNF, and the maximum values of 5 s and 2.6 kg/m3 were achieved at 2% and 3% CNF, respectively. Furthermore, the compressive strength increased with an increase in curing age and CNF content (until 0.5%), and the maximum value of compressive strength was achieved as 89 MPa for 0.5% CNF at 28-days of curing. The dry density results increased with the increase in CNF contents at 7-days of curing. The ultrasound pulse velocity and strength ultrasound decreased with the increase in CNF contents. The results showed that the inclusion of CNF improved the microstructure and formed crack bridging. In conclusion, CNF (up to 0.5%) can be used for the production of SCC.

Feasibility of bionanocomposite films fabricated using capsicum leaf protein and cellulose nanofibers

In this study, the feasibility of fabricating protein-based bionanocomposite films (PBBFs) was analysed by applying capsicum leaf protein (CLP) and cellulose nanofiber (CNF) as raw materials. The effects of different amounts of CNF (solid content 2%) on physicochemical and material properties of PBBFs were investigated. The results showed nanoscale CNFs exhibited good interfacial compatibility with CLP. The hydroxyl groups on the CNF surface promoted the association of hydrogen bonds between CLP, glycerol and CNF, which improved the crystal structure and thermal stability of PBBFs. Concurrently, the mechanical properties and hydrophobicity of PBBFs are also enhanced. PBBFs with 60% CNF content have maximum flexibility and hydrophobicity. All PBBFs exhibited ultraviolet barrier performance, indicating that PBBFs had potential application prospects in the development of degradable food packaging materials. The results of the present study can provide a theoretical basis for the efficient utilisation of capsicum planting waste while improving the ecosystem.

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.

Effect of Annealing Temperature on Mechanical Properties of Cellulose Nano Fiber / Poly(lactic acid) Composites

Cellulose Nano Fiber (CNF) and Poly(lactic acid) (PLA) are known to have low adhesion. In conventional research, complex processes such as the use of additives are required to improve adhesion. In this study, PLA is shrunk by crystallization during heat treatment. This shrinkage is thought to improve adhesion. In this study, changes in the mechanical properties of CNF/PLA composites were investigated by varying the CNF content (0 and 10 mass%) and heat treatment conditions (3.5 hours at 70°C, and 130°C). Mechanical properties were investigated by tensile tests. The effect of annealing on the mechanical properties of CNF/PLA was investigated by tensile tests. The results showed that annealing and compositing with CNF reduced tensile strength and strain at break, and increased elastic modulus. Annealing of PLA resulted in an increase in PLA density and a shrinkage rate of 1.286%. These results suggest that the improvement in elastic modulus is due to the high elastic modulus of CNF and the improvement in adhesion between CNF and PLA due to crystallization.

Ternary Nanocomposite System Composing of Graphene Nanoplatelet, Cellulose Nanofiber and Jatropha Oil Based Waterborne Polyurethane: Characterizations, Mechanical, Thermal Properties and Conductivity.

This work aims to evaluate the performance of graphene nanoplatelet (GNP) as conductive filler with the presence of 0.5 wt.% cellulose nanofiber (CNF) on the physical, mechanical, conductivity and thermal properties of jatropha oil based waterborne polyurethane. Polyurethane was made from crude jatropha oil using an epoxidation and ring-opening process. 0.5, 1.0, 1.5, 2.0 wt.% GNP and 0.5 wt.% CNF were incorporated using casting method to enhance film performance. Mechanical properties were studied following standard method as stated in ASTM D638-03 Type V. Thermal stability of the nanocomposite system was studied using thermal gravimetric analysis (TGA). Filler interaction and chemical crosslinking was monitored using Fourier-transform infrared spectroscopy (FTIR) and film morphology were observed with field emission scanning electron microscopy (FESEM). Water uptake analysis, water contact angle and conductivity tests are also carried out. The results showed that when the GNP was incorporated at fixed CNF content, it was found to enhance the nanocomposite film, its mechanical, thermal and water behavior properties as supported by morphology and water uptake. Nanocomposite film with 0.5 wt.% GNP shows the highest improvement in term of tensile strength, Young’s modulus, thermal degradation and water behavior. As the GNP loading increases, water uptake of the nanocomposite film was found relatively small (<1%). Contact angle test also indicates that the film is hydrophobic with addition of GNP. The conductivity properties of the nanocomposite film were not enhanced due to electrostatic repulsion force between GNP sheet and hard segment of WBPU. Overall, with addition of GNP, mechanical and thermal properties was greatly enhanced. However, conductivity value was not enhanced as expected due to electrostatic repulsion force. Therefore, ternary nanocomposite system is a suitable candidate for coating application.

Structural and mechanical characterisation of cellulose nanofibers (CNF) from Pennisetum Purpureum reinforced with polylactic acid (PLA)

This study aims to develop a composite scaffold based on polylactic acid reinforced with cellulose nanofibers from Pennisetum purpureum (PLA/CNF). The composite scaffolds were prepared via solvent casting and particulate leaching technique; sodium chloride (NaCl) was used as the porogen material. The influence of CNF on PLA is investigated; scaffolds were fabricated with different content of CNF (5%, 10% and 15%). The prepared composite scaffold was characterised using porosity measurements, Fourier-transform infrared spectroscopy (FTIR) and the compression strength and modulus were also evaluated in this study. The PLA/CNF scaffolds were highly porous with porosity higher than 80%. It was also shown that the porosity had a slight decrease with increasing CNF contents due to the compact arrangement of CNF within the scaffolds. Compression strength and modulus also show an increase in value as the CNF content increases. The results also show that introducing CNF to the PLA matrix can be considered beneficial for cartilage regeneration, cell attachment, and extracellular matrix (ECM) production.

Enhancement of the interlaminar fracture toughness and damping properties of carbon fiber reinforced composites using cellulose nanofiber interleaves

Cellulose nanofibers (CNFs), with excellent mechanical properties, could be obtained from plant fibers and prepared by the combined mechanical and chemical methods. Waterborne epoxy was used to reduce the hydrophilicity of CNFs before the CNFs films were prepared by freeze-drying and inserted between layers of carbon fiber reinforced polymer composites (CFRPs). The effects of CNFs content on the interlaminar fracture toughness and damping properties of CFRPs were investigated, and the lay-up sequences of CNFs interleaves on the loss factors of CFRPs were also examined. The results reveal that by the addition of 0.075 wt% and 0.05 wt% CNFs, the mode I and mode II interlaminar fracture toughness of CFRPs were improved by 22% and 25%, respectively. With the addition of 0.25 wt% CNFs, the loss factor of CFRPs was increased by 31%. However, the tensile and flexural properties of interleaved CFRP were only slightly decreased.

Effects of cellulose nanofiber content on impact properties of carbon fiber reinforced epoxy composites with the cellulose nanofiber dispersion layer

Cellulose nanofibers (CNFs) are environmentally friendly materials with a high specific strength. To enhance the impact properties of the carbon fiber reinforced plastics (CFRPs), a method for inserting a CNF dispersion layer between prepregs was developed. By using an aqueous solution of epoxy resin, the hydrophobic treatment of CNF became unnecessary. In this study, CFRP with CNF dispersion layers was fabricated with different CNF content. The impact energy absorbed by the CFRP specimen was increased with the increasing CNF content, and the Charpy impact value increased up to a maximum of 21% by the CNF dispersion layers. Highlights Carbon fiber reinforced plastics (CFRPs) specimens with the cellulose nanofiber (CNF) dispersion layer were fabricated. The specimens were fabricated by varying the content of CNF. Impact energy absorbed by the CFRP specimen was increased with increased CNF content. Charpy impact value increased up to 21%; optimum ductility index value was clarified.

Strong Polyamide-6 Nanocomposites with Cellulose Nanofibers Mediated by Green Solvent Mixtures.

Cellulose nanofiber (CNF) as a bio-based reinforcement has attracted tremendous interests in engineering polymer composites. This study developed a sustainable approach to reinforce polyamide-6 or nylon-6 (PA6) with CNFs through solvent casting in formic acid/water mixtures. The methodology provides an energy-efficient pathway towards well-dispersed high-CNF content PA6 biocomposites. Nanocomposite formulations up to 50 wt.% of CNFs were prepared, and excellent improvements in the tensile properties were observed, with an increase in the elastic modulus from 1.5 to 4.2 GPa, and in the tensile strength from 46.3 to 124 MPa. The experimental tensile values were compared with the analytical values obtained by micromechanical models. Fractured surfaces were observed using scanning electron microscopy to examine the interface morphology. FTIR revealed strong hydrogen bonding at the interface, and the thermal parameters were determined using TGA and DSC, where the nanocomposites’ crystallinity tended to reduce with the increase in the CNF content. In addition, nanocomposites showed good thermomechanical stability for all formulations. Overall, this work provides a facile fabrication pathway for high-CNF content nanocomposites of PA6 for high-performance and advanced material applications.

Biocomposites Based on Agar and Cellulose Nanofibers Prepared from Carrot Slag

In this study, the effect of cellulose nanofibers (CNF) prepared from carrot slag on the properties of agar biocomposite films is investigated. The composite film was characterized by ultraviolet–visible spectroscopy (UV-Vis), tensile test, fourier transforms infrared (FT-IR) spectroscopy and Transmission electron microscopy (TEM). The transmittance, mechanical properties and chemical structure of the composite film containing different CNF content (0.1, 0.3 and 0.5 phr based on agar) were studied. The UV-Vis showed that the transmittance of the film was decreased with increasing content of CNF. The FT-IR spectrum showed that the generation of hydrogen bonds leads to good interface bonding between Agar and CNF. Moreover, the performance of the bionanocomposite was improved by the addition of CNF. The composite containing 0.3 phr CNF results in a maximum tensile strength of 25.97 MPa. However, the tensile strength of the 0.5 phr CNF containing one is reduced to 24.42 MPa due to the agglomeration of CNF. The TEM shows that the diameter of CNF is 2.5 nm and the length is 18.20 nm. The usage of CNF obtained from carrot slag can not only recycle the waste from food industry, but also can be used as a reinforcing agent for preparing biodegradable composite film. It has potential uses in the development of biodegradable food packaging materials and biomedical applications.

Edible chitosan/cellulose nanofiber nanocomposite films for potential use as food packaging

ABSTRACT In this study, bio-nanocomposites of chitosan (CS)/glycerol (Gly)/cellulose nanofibers (CNF) were prepared using the solvent casting method. Effects of Gly and CNF content on properties of nanocomposites were investigated by the FTIR, SEM, tensile, TGA, swelling test, solubility analysis, water vapour permeability and contact angle measurements. Results showed that solubility of the CS-Gly films was sharply decreased by increasing Gly content. Also, plastic-like behaviour of the films was disappeared and they achieved a quasi-elastomeric structure by increasing the amount of Gly in the CS films. Elongation at the break was increased by increasing Gly content from 23% to 94% for CS-0%Gly to CS-20%Gly. Young’s modulus of the films was increased from 1.45 to 3.46 MPa by increasing CNF content from 0 to 0.5 wt.%. Thus, it was concluded that improvement of barrier and mechanical properties is correlated with both nanostructure of CNFs and the interactions between CS, CNFs and Gly.

High Performance PA 6/Cellulose Nanocomposites in the Interest of Industrial Scale Melt Processing.

On an industrial scale, it is a challenge to achieve cellulose based nanocomposites due to dispersion issues and high process temperatures sensitivity. The current study describes methods to develop mechanically strong and thermally stable polyamide 6 (PA 6) and cellulose nanofibers (CNF) composites capable of tolerating high processing temperatures. With PA 6 being a very technical polymer matrix to be reinforced with CNF, good dispersion can be achieved with a high speed kinetic mixer and also shield the CNF from excess thermal degradation by implementing extremely short processing time. This paper presents an industrially feasible method to produce PA 6/CNF nanocomposites with high CNF composition processed by a high speed kinetic mixer (GELIMAT®) followed by compression molding to obtain a homogenous and thermally stable nanocomposites aimed at high performance applications. PA 6 was reinforced with three different wt % formulations (5, 15 and 25 wt %) of cellulose nanofibers. The resulting nanocomposites exhibited significant increase in Young’s modulus and ultimate strength with CNF content, owing to the effective melt processing and the surface charge density of the CNF, which necessitated the dispersion. The thermal stability and polymer crystallinity with respect to CNF composition for the PA 6/CNF nanocomposites were examined by TGA and DSC analysis. Rheology studies indicated that viscosity of the composites increased with increase in CNF composition. Overall, this work demonstrates industrially viable manufacturing processes to fabricate high performance PA 6/CNF nanocomposites.

Cellulose nanofibers and the film-formation dilemma: Drying temperature and tunable optical, mechanical and wetting properties of nanocomposite films composed of waterborne sulfopolyesters

HypothesisWaterborne sulfopolyesters have gained considerable interest as coating materials due to their excellent film-forming and optical properties. Their commercial use has been limited, however, due to their fragile nature. Incorporating cellulose nanofiber (CNF), a sustainable biopolymer, into the polymer matrix is expected to enhance the mechanical integrity of the nanocomposite as these two components synergistically interact. ExperimentsIn this study, we have investigated the suspension and film characteristics of three sulfopolyesters varying in charge density, glass transition temperature and molecular weight, as well as their mixtures with CNF. We have performed steady-shear rheology on mixtures with different CNF loading levels, and resulting films have been subjected to quasistatic uniaxial tensile and water contact-angle tests to elucidate the effects of CNF on mechanical and surface properties. FindingsAddition of CNF to waterborne polyester promotes shear-thinning behavior that remains unaffected by the CNF content. Solid films cast from these suspensions possess enhanced mechanical properties, as well as tailorable surface hydrophilicity, depending on composition and film-drying temperature. Tensile tests reveal that films containing 10 wt% CNF display the greatest mechanical improvements, suggesting the existence of a previously unidentified Goldilocks composition window.

3D printed alginate-cellulose nanofibers based patches for local curcumin administration

Alginate and nanocellulose are potential biomaterials to be employed as bioinks for three-dimensional (3D) printing. Alginate-cellulose nanofibers (A-CNF) formulations with CNF amounts up to 5 wt% were developed and rheologically characterized to evaluate their printability. Results showed that formulations with less than 3 wt% CNF did not present suitable characteristics to ensure shape fidelity after printing. Selected A-CNF bioinks were 3D printed and freeze-dried to obtain porous scaffolds. Morphological and mechanical analysis were performed, showing that CNF contributed to the reinforcement of the scaffolds and modulated their porosity. The applicability for drug delivery was evaluated by the addition of curcumin to printable A-CNF formulations. The curcumin loaded bioinks were successfully 3D printed in patches and the in vitro release tests showed that alginate and CNF played an important role in curcumin stabilization, whereas the CNF content and the disintegration of the scaffold were essential in the release kinetics.

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.

Cellulose Nanofiber Nanocomposite Pervaporation Membranes for Ethanol Recovery

In spite of the growing interest to exploit nanocellulose in membranes for water purification, reverse osmosis, packaging, and other applications, examples of nanocellulose-containing membranes for pervaporation are rather limited. We here report the preparation of dense nanocomposite pervaporation membranes consisting of a polystyrene-block-polybutadiene-block-polystyrene (SBS) matrix and high-aspect-ratio cellulose nanofibers (CNFs). The membranes were produced by a solvent casting evaporation process, and the CNF concentration was systematically varied. At the highest CNF concentration (15 wt %), a 5-fold increase in Young’s modulus (271 MPa) and a 10-fold increase in the yield strength (18 MPa) were observed, while the elongation at break (37%) remained appreciable, suggesting that the CNFs form a reinforcing network in the SBS matrix. At the same time, the water permeability and sorption doubled and increased ten times (at relative humidity = 100%). Pervaporation experiments were carried out with a 10 wt % ethanol/water mixture at 40 °C. A 3-fold increase in mass fluxes was observed at a CNF content of 15 wt %, which was accompanied by a 40% decrease in the separation factor. This resulted in an increase of the pervaporation separation index from 66.5 g m–2 h–1 (neat SBS) to 89.4 g m–2 h–1 (15 wt % CNF nanocomposite), indicating that the relative increase in fluxes more than compensates the reduced separation efficiency.

Broadband terahertz spectroscopy of cellulose nanofiber-reinforced polypropylenes

Cellulose nanofiber (CNF)-reinforced polypropylenes (PPs) with different CNF content were investigated by Fourier transform terahertz (THz) spectroscopy over the frequency range of 1–10 THz. Absorption peaks of pure PP were identified at 3.1, 5.1, 7.5, and 9.6 THz, which indicate the isotactic structure is formed. A new peak at 7.0 THz appeared when CNF was added, while the PP peaks remained unchanged. Conventional X-ray diffraction (XRD) spectroscopy was also performed for comparison. The XRD results do not allow to determine the effect of CNF content in the properties of the composite. In contrast THz spectroscopy effectively showed the relationship between CNF content and the mechanical properties of the samples. The 7.0 THz can be used as an indicator for the nondestructive and noninvasive analysis of CNF-PPs.

Synergistic Effect of Cellulose Nanofiber and Nanoclay as Distributed Phase in a Polypropylene Based Nanocomposite System.

Since the plastic-based multilayer films applied to food packaging are not recyclable, it is necessary to develop easily recyclable single materials. Herein, polypropylene (PP)-based cellulose nanofiber (CNF)/nanoclay nanocomposites were prepared by melt-mixing using a fixed CNF content of 1 wt %, while the nanoclay content varied from 1 to 5 wt %. The optimum nanoclay content in the PP matrix was found to be 3 wt % (PCN3), while they exhibited synergistic effects as a nucleating agent. PCN3 exhibited the best mechanical properties, and the tensile and flexural moduli were improved by 51% and 26%, respectively, compared to PP. In addition, the oxygen permeability was reduced by 28%, while maintaining the excellent water vapor permeability of PP. The improvement in the mechanical and barrier properties of PP through the production of PP/CNF/nanoclay hybrid nanocomposites suggested their possible application in the field of food packaging.

The reinforcement effect of cellulose nanofiber on Young’s modulus of polyvinyl alcohol gel produced through the freeze/thaw method

Cellulose nanofiber (CNF) is the most effective reinforcement fiber for enhancing the physical properties of water-soluble polymers. Here, effect of CNF on the Young’s modulus of a polyvinyl alcohol (PVA) hydrogel produced through the freeze/thaw method is examined. PVA/CNF composite gels with different contents of CNF and PVA were produced without significant aggregation of CNFs during the freeze/thaw process. The Young’s modulus of the produced PVA/CNF gel gradually increased as the CNF content increased, and it was confirmed that CNF had a marked reinforcement effect. In gel with PVA = 7 vol%, percolation networks formed at CNF ≥ 0.6 vol%. Furthermore, adding ca. CNF = 1.5 vol% resulted in a 250% increase in the gel’s Young’s modulus. In addition, mechanical interaction was observed between the PVA and CNF networks. It was suggested that, similarly to CNF networks, PVA networks also limit the deformation of CNF networks.

Development of eco-friendly modified cellulose nanofiber reinforced polystyrene nanocomposites: thermal, mechanical, and optical properties

The fiber extracted from pineapple leaf was treated by 2,2,6,6-tetramethylpiperidine (TEMPO) to prepare the cellulose nanofiber (CNF). Subsequently, it was eco-friendly modified by suspension polymerization and the sol-gel method, respectively, in order to improve its affinity with the polymer matrix. The obtained CNFs was reinforced into a polystyrene (PS) substrate to acquire nanocomposites. The FTIR results showed that after alkali and acid neutralization treatment, lignin and impurities of PLF can be effectively removed. In addition, the nano-scale fibers were obtained by TEMPO oxidation reaction (OF), suspension polymerization (SF) and sol-gel modification (GF). The results of contact angle revealed the improved hydrophobicity of CNFs after modification. Especially the SF, resulted in hydrophobicity (55.84o) as compared with that of the OF (12.02 o). The XRD results showed that the crystallinities of OF, SF and GF are 80.78, 78.48 and 67.16%, respectively. The TGA analysis revealed that the degradation temperature and char yield of the GF (14.14%) were higher than those of OF (6.02%) and SF (8.44%). Tensile studies of the nanocomposites indicated improved mechanical properties by the addition of modified CNFs compared to the TEMPO-reacted ones. The tensile strengths of nanocomposite PSCNF (31.1 MPa) and PSGPH (28.1 MPa) are better than those of POCNF (26.7 MPa). The heat distortion temperature (HDT) of the nanocomposites increased with increasing different kinds of CNFs content. Among all of the nanocomposites, the 3 wt% GF containing one showed the best value (93.8 °C), and the increment was 3.5 °C as compared with pristine PS (90.3 °C). The optical properties of the materials revealed that TEMPO oxidized CNFs without modification has poor light transparency due to its poor compatibility and fiber aggregation.