Use Of Cellulose Nanofibers Research Articles

Preparation of polylactic acid reinforced with cellulose nanofibers toward photochromic self-healing adhesive for anti-counterfeiting applications

There are a number of drawbacks with photochromic adhesives, including their poor durability, high price tag, and lackluster performance. On the other hand, self-healable adhesives have shown to be durable and robust than conventional alternatives. Hydrogel adhesives that change color in response to ultraviolet light were created for usage in self-healable authenticating stamps. In this context, a combination of cellulose nanofibers (CNFs), polylactic acid (PLA) and nanoparticles of lanthanide aluminate (NLA) were prepared to generate an organic-inorganic hybrid hydrogel adhesive with self-healing properties. NLA agglomerates were avoided due to the use of CNFs as a nanofiller and dispersion agent. Colorless stamps require that NLA to be dispersed consistently in the CNFs/PLA hydrogel without clumping. This film becomes green when irradiated with ultraviolet, as indicated by luminescence spectra and CIE Lab coordinates. When illuminated at 365 nm, the paper sheets emitted light with a wavelength of 519 nm. The morphologies of prints were analyzed by different analytical methods. Diameter measurements from a transmission electron microscope (TEM) of the synthesized NLA ranged from 5 to 9 nm, whereas CNFs displayed diameters of 40–60 nm. The current NLA@CNFs/PLA hydrogel presents a reliable anti-counterfeiting solution for various authenticating products.

Comparison of the Effect of Nano Cellulosic Additives on Rheological Parameters for 3D Printable Concretes

In 3D printable concretes, fresh requirements such as pumpability, workability, constructability are affected by the rheological properties of the mixture. High yield stress and high viscosity cause blockages in the transmission line, while low yield stress and low viscosity cause the mixture to not provide the required shape stability. Even if the mixture to be printed has suitable rheological parameters, it is very important in terms of workability that it can be preserved over time. Here, cellulose nanocrystals and cellulose nanofibers were used in cement paste mixtures in order to ensure sufficient workability time in 3D printable concrete mixtures, and also to ensure that the originally designed rheological properties can be maintained over time. The Bingham model, which was created as a result of the measurements made with the viscometer device, was used to evaluate the rheological parameters of the mixes containing cellulose nanocrystal and cellulose nanofiber additions in varied amounts. As a result of the study, it was determined that the yield stress of the reference sample increased by 290% 45 minutes after the preparation of the mixture, while this rate decreased to 135% in the use of cellulose nanocrystals and to 79% in the use of cellulose nanofibers. While it increased by 205% at the end, this rate decreased to 37% with cellulose nanofibers and to 68% with cellulose nanocrystals. When the different additives are compared, it was concluded that cellulose nanofiber may be more effective than cellulose nanocrystal in controlling the increase in viscosity and yield stress over time.

Contaminant microorganisms in the in vitro evaluation of cellular responses of cellulose nanofibers and their microbial inactivation using gamma irradiation

Cellulose nanofibers (CNFs) are fibrous nanomaterials produced from plants. Since some nanomaterials are toxic, toxicity evaluation, including in vitro examinations using cultured cells, is essential for the effective use of CNFs. On the other hand, microorganisms in the environment can contaminate CNF suspensions. The contamination of CNF samples and the effects of contaminating microorganisms on in vitro examinations were investigated in this study. Microorganism contamination in CNF samples was examined, and microbial inactivation of CNF suspensions using gamma irradiation was evaluated. After gamma-ray irradiation at absorbed doses of 0.5, 1, 5, and 10 kGy, the cellular effects of CNF suspensions were examined using 6 types of cultured cell, HaCaT, A549, Caco-2, MeT-5A, THP-1, and NR8383 cells. CNF samples were contaminated with bacteria and CNF suspensions exhibited endotoxin activity. Gamma irradiation effectively inactivated the microorganisms contained in the CNF suspensions. When the absorbed dose was 10 kGy, the fiber length of CNF was shortened, but the effect on CNF was small at 1.0 kGy or less. CNF suspensions showed lipopolysaccharides (LPS)-like cellular responses and strongly induced interleukin-8, especially in macrophages. Absorbed doses of at least 10 kGy did not affect the LPS-like activity. In this study, it was shown that the CNF suspension may be contaminated with microorganisms. Gamma irradiation was effective for microbial inactivation of suspension for invitor toxicity evaluation of CNF. In vitro evaluation of CNFs requires attention to the effects of contaminants such as LPS.

Antioxidant cellulose nanofibers/lignin-based aerogels: a potential material for biomedical applications

BackgroundLignin is a naturally occurring and aromatic biopolymer with well-known antimicrobial and antioxidant properties. Thus, in this work, the use of cellulose nanofibers (CNF) and lignin to produce ultra-light aerogels for biomedical applications was studied. Aerogels containing varying amounts of lignin (0–30 wt%) and different concentrations of the crosslinking agent Fe3+ (25–100 mM) were developed.ResultsThe different bioaerogels were fully characterized and their physical, mechanical and bioactive properties analyzed. It was observed that the bioaerogels soluble fraction tends to decrease as the lignin content increases for the different Fe3+ concentrations, due to lignin–CNF interactions through hydrogen bonds. The bioaerogels containing lignin showed remarkable radical scavenging activity as the DPPH concentration decreased with time. This confirms the benefits of including lignin in bioaerogels to impart antioxidant properties. To study the suitability of the produced bioaerogels for controlled drug release, the release of tetracycline (TC) was studied. All of the bioaerogels released TC in a sustained manner for 6 h and presented similar profiles. However, the bioaerogels containing higher concentrations of crosslinker showed a higher release of TC. The TC loading conferred clear antimicrobial activity against S. aureus as expected, unlike the insignificant antimicrobial activity of the bioaerogels without TC. The biocompatibility of the samples was demonstrated for all materials produced (with and without TC loading) by the Kruskal–Wallis test with multiple comparisons. After observation of cell morphology, no significant differences were evident suggesting that the CNF–lignin bioaerogels present optimal biocompatibility for use in the biomedical and pharmaceutical industry.ConclusionsThe CNF–lignin bioaerogels presented in this work highlights their promising application as biomedical applications, such as wound dressings due to their biocompatibility, antimicrobial and antioxidant properties, as well as their swelling and solubility properties.Graphical

Composite of Cellulose-Nanofiber-Reinforced Cellulose Acetate Butyrate: Improvement of Mechanical Strength by Cross-Linking of Hydroxyl Groups

A great challenge hindering the use of cellulose nanofibers (CNF) as a reinforcing filler in bio-based polymeric matrices are their poor chemical compatibility. This is because of the inherent hydrophilic nature of CNF and the hydrophobic nature of the polymeric matrix. In this study, cellulose laminates were prepared by using CNF as a filler and cellulose acetate butyrate (CAB) as the polymer matrix. To improve the compatibility between CAB and CNF, the residual hydroxyl groups of CAB and the hydroxyl groups on the surface of CNF were cross-linked with bio-derived polyisocyanurate D376N (STABiO™). The composite material was obtained in one step by sandwiching a CNF sheet (10 wt%) coated with a cross-linking agent between CAB films (90 wt%) using hot pressing. When 14.3 wt% of the cross-linking agent to the total weight of CNF and CAB was added, the tensile strength and flexural strength were improved by 72.4% and 16.3%, respectively, compared with neat CAB. It was concluded that this increase in strength is a result of both: cross-linking between the CNF sheets as well as the cross-linking occurring at the CNF/CAB interface.

Property enhancement of epoxidized natural rubber nanocomposites with water hyacinth-extracted cellulose nanofibers

Cellulose nanofibers (CNFs) have been widely used as reinforcement in various polymer matrices; however, limited studies of the use of CNFs in epoxidized natural rubber (ENR) have been reported. Here, we successfully prepared CNF-reinforced ENR nanocomposites with superior mechanical performance. CNFs were disintegrated from water hyacinth (Eichhornia crassipes) using high-pressure homogenization, and ENR nanocomposites with CNFs were fabricated by initial mixing and hot pressing. The crosslink densities of the nanocomposites with CNFs were higher than that of the neat ENR. Due to stronger interfacial interactions between the hydroxyl groups of the CNFs and the functional groups of the ENR, stress could be efficiently transferred from the ENR matrix to the stiff CNFs, resulting in a significant increase in the mechanical properties. Compared with those of the neat ENR, the tensile strength and Young's modulus of the ENR nanocomposites were improved by 80 and 39 %, respectively, with the incorporation of 2 parts per hundred rubber (phr) CNFs, whereas no loss in elongation at break was observed. The introduction of CNFs also improved the oil resistance of the nanocomposites. Therefore, CNFs could be the potential reinforcing agent in the ENR nanocomposites used in the various engineering applications of the rubber material.

Multiscale kapok/cellulose aerogels for oil absorption: The study on structure and oil absorption properties

An efficient and economic kapok/cellulose aerogel for waste oil treatment was successfully fabricated via simple freeze-drying and surface modification. To investigate their oil absorption performance, various aerogels by multi-scale cellulose and different lengths of kapok fibers were characterized. The use of cellulose nanofibers (CNF) enabled aerogels to possess remarkably uniform pore size and structural integrity, while the introduction of kapok improved their mechanical property, oil absorption and retention performance. For kapok/microfibrillated cellulose (MFC) aerogels, an excessively enlarged porous structure caused by long fibers would damage the structural stability of aerogels and reduce their oil absorption capability. Compared with the sheet-like structure formed by self-aggregated MFC, filamentous CNF exhibited better entanglement characteristics and possessed a more positive impact on enhancing the structural integrity and mechanical properties of aerogels. These aerogels presented ultra-low density (4.9 mg/cm3), desirable hydrophobicity (147.6°), outstanding oil absorption (141.9 g/g) and retention (97.7 %) capacity, and excellent selective sorption property, making them ideal absorbents for oil spill cleaning.

Report on the NEDO project “Training Course for Practical Use of Cellulose Nanofibers” in FY2020

Report on the NEDO project “Training Course for Practical Use of Cellulose Nanofibers” in FY2020

Recent Advances in Functional Materials through Cellulose Nanofiber Templating.

Advanced templating techniques have enabled delicate control of both nano- and microscale structures and have helped thrust functional materials into the forefront of society. Cellulose nanomaterials are derived from natural polymers and show promise as a templating source for advanced materials. Use of cellulose nanomaterials in templating combines nanoscale property control with sustainability, an attribute often lacking in other templating techniques. Use of cellulose nanofibers for templating has shown great promise in recent years, but previous reviews on cellulose nanomaterial templating techniques have not provided extensive analysis of cellulose nanofiber templating. Cellulose nanofibers display several unique properties, including mechanical strength, porosity, high water retention, high surface functionality, and an entangled fibrous network, all of which can dictate distinctive aspects in the final templated materials. Many applications exploit the unique aspects of templating with cellulose nanofibers that help control the final properties of the material, including, but not limited to, applications in catalysis, batteries, supercapacitors, electrodes, building materials, biomaterials, and membranes. A detailed analysis on the use of cellulose nanofibers templating is provided, addressing specifically how careful selection of templating mechanisms and methodologies, combined toward goal applications, can be used to directly benefit chosen applications in advanced functional materials.

Starch-based nanocomposites with cellulose nanofibers obtained from chemical and mechanical treatments

Cellulose nanofibers (CNFs) were isolated from unripe banana peel by acid hydrolysis, with different acid concentrations (0.1%, 1.0% and 10% v/v), followed by mechanical treatment with high-pressure homogenizer. Banana starch-based films added with CNFs (0.2% w/w) as a reinforcing agent were produced by the casting method. The rheological behavior of aqueous dispersions of CNFs (1.0% w/w) and their effects on the properties of nanocomposite films were investigated. All aqueous dispersions of CNFs showed gel-like behavior and, when incorporated to the films, CNFs improved their water barrier properties and mechanical resistance as demonstrated by the increase in tensile strength and Young's modulus. Moreover, CNFs were well dispersed in the composite matrix. CNFs prepared at higher concentration, followed by mechanical treatment (FNM1 and FNM10), formed films with low moisture (13.66%) and solubility in water (24.1%). Whereas, CNFs prepared at the lowest acid concentration without mechanical treatment (FN0.1) led to films with high elongation at break (30.6%) and good tensile strength (12.3 MPa). Regardless of the used CNFs, all the nanocomposites displayed lower UV/light transmission than control film. The nanocomposite has potential use in food packaging, since the use of CNFs can promote improvements on barrier, optical and mechanical properties. Cellulose nanofibers isolated from agro-industrial residues offer the potential to reinforce composites of biodegradable polymers, producing a value-added material.

Research on the Strengthening Advantages on Using Cellulose Nanofibers as Polyvinyl Alcohol Reinforcement.

The present work aims to combine the unique properties of cellulose nanofibers (CNF) with polyvinyl alcohol (PVA) to obtain high-performance nanocomposites. CNF were obtained by means of TEMPO-mediated ((2,2,6,6-Tetramethylpiperidin-1-yl)oxyl) oxidation, incorporated into the PVA matrix by means of compounding in a single-screw co-rotating internal mixer and then processed by means of injection molding. It was found that CNF were able to improve the tensile strength of PVA in 85% when 4.50 wt % of CNF were added. In addition, the incorporation of a 2.25 wt % of CNF enhanced the tensile strength to the same level that when 40 wt % of microsized fibers (stone groundwood pulp, SGW) were incorporated, which indicated that CNF possessed significantly higher intrinsic mechanical properties than microsized fibers. SGW was selected as reference for microsized fibers due to their extended use in wood plastic composites. Finally, a micromechanical analysis was performed, obtaining coupling factors near to 0.2, indicating good interphase between CNF and PVA. Overall, it was found that the use of CNF is clearly advantageous to the use of common cellulosic fibers if superior mechanical properties are desired, but there are still some limitations that are related to processing that restrict the reinforcement content at low contents.

Erratum to: Use of cellulose nanofibers as a denture immersing solution.

Erratum to: Use of cellulose nanofibers as a denture immersing solution.

Use of cellulose nanofibers as a denture immersing solution.

The purpose of this study was to investigate the influence of cellulose nanofibers (CNF) solution on the mechanical and biological properties of denture base resins (DBR). Two types of CNFs obtained from bamboo (BB) and needle-leaved (NB) trees were used in this study. We prepared 18 different CNF solutions based on their fibrillation (A-low, B-middle, and C-high) and concentration (0.05, 0.10, and 0.20 wt%). A heat-polymerized acrylic resin was used as DBR. The contact angles for each specimen were measured after immersion. The flexural properties of the immersed specimens, and the biological properties of the CNF solutions were examined. Specimens immersed in CNF-NB-C-0.05 wt% solution presented with the lowest contact angles. Specimens in CNF-NB-C and CNF-BB-A groups showed higher flexural modulus values. No cytotoxic or antimicrobial effects were observed for the CNF solutions. This study suggest that CNF solution may improve the surface wettability of the DBR without affecting its flexural property.

A Simple Approach for the Synthesis of Cellulose Nanofiber Reinforced Chitosan/PVP Bio Nanocomposite Film for Packaging

The development of chitosan-based food packaging film has been increasing due to its wider availability, biodegradability, low-cost, and renewability. The purpose of this study was to develop cellulose nanofibers (CNFs) reinforced Chitosan/PVP(CHP) green bio nanocomposite film by solvent casting method with enhanced barrier and mechanical property. CNFs of dimension 9–11 nm and 100–200 nm were extracted from jute fibers by directly treating it with HNO3–NaNO2 mixture. Bio nanocomposite films were synthesized with various concentrations of CNFs and evaluated using SEM, TGA/DTG and XRD to analyze the morphology, thermal behavior and crystallinity of bio nanocomposite films. SEM analysis revealed the uniform dispersion of CNFs in CHP matrix. Thermal stability of prepared bio nanocomposite films was improved with the loading of 5 wt% of cellulose nanofibers. ATR(FT-IR) spectra shows physical interaction between all the components of bio nanocomposite film. The bio nanocomposite films were also characterized for physical property like thickness, mechanical testing and barrier properties. The addition of CNFs significantly enhanced the mechanical property of bio nanocomposite films. Furthermore, water and oxygen transmission rate of bio nanocomposite film decreased with the increase in CNFs concentration. Overall the performed studies confirmed, the use of CNFs in polymer matrix makes it possible to produce a flexible, transparent, thermally stable bio nanocomposite film with enhanced mechanical and barrier properties for food packaging applications.

Electrically conductive polyacrylamide/carbon nanotube hydrogel: reinforcing effect from cellulose nanofibers

The development of polymeric hydrogels with new functionalities is becoming an aspiration in various fields. Here we report a simple method to fabricate a conductive polyacrylamide (PAM)-based hydrogel by the incorporation of carbon nanorubes (CNTs). However, the major challenge for these hydrogels is CNT aggregation in PAM, which decreases both mechanical and electrical properties of the composite hydrogels. Inclusion of cellulose nanofibers (CNFs), is expected to disperse the CNTs well, thereby reinforcing the PAM hydrogels. Hence, by mixing the CNFs and CNTs in the AM hybrid solutions, a PAM/CNF/CNT composite hydrogel is prepared through in situ polymerization. Specifically, with incorporation of 1 wt% CNF and 1 wt% CNT into PAM, the PAM/CNF/CNT-1 hydrogel, with an electrical conductivity of 8.5 × 10−4 S/cm, shows a threefold higher fracture tensile strength than the pure PAM hydrogel. Given the improved mechanical properties and electrical conductivity, the use of CNF as a reinforcing agent for both PAM and CNT provide a versatile method to fabricate conductive hydrogels, and has potential to expand their application in the field of bio-medical engineering and electrical devices.

Enhancement of desalination performance of thin-film nanocomposite membrane by cellulose nanofibers

The incorporation of nanoparticles in a polymer membrane has been recognised as an effective strategy to improve the membrane performance in water processing. However, the leaching of nanoparticles from the membrane is potentially a concern as it may lead to the change of membrane properties and contamination of treated water. In this work, 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized cellulose nanofibers (CNFs) were for the first time incorporated into the polyamide layer of thin film composite (TFC) reverse osmosis (RO) membrane during interfacial polymerization to improve its membrane performance. CNFs are made from renewable and sustainable resources and they are non-toxic and environmentally friendly. The optimal loading of CNFs within the TFC membrane enhanced the permeance of the fabricated membranes by more than 50% (29.8 L m−2 h−1 at operating pressure of 1.5 MPa), whilst retaining high NaCl rejection at 96.2%. Chlorine stability test results indicated that the nanocomposite membranes showed better chlorine resistance performance than bare TFC membranes. This work successfully demonstrated the potential use of CNFs as a low cost and non-toxic filler to improve the performance of RO membranes for water desalination.

Signal enhancement on gold nanoparticle-based lateral flow tests using cellulose nanofibers

Lateral flow paper-based biosensors merge as powerful tools in point-of-care diagnostics since they are cheap, portable, robust, selective, fast and easy to use. However, the sensitivity of this type of biosensors is not always as high as required, often not permitting a clear quantification. To improve the colorimetric response of standard lateral flow strips (LFs), we have applied a new enhancement strategy that increases the sensitivity of LFs based on the use of cellulose nanofibers (CNF). CNF penetrate inside the pores of LFs nitrocellulose paper, compacting the pore size only in the test line, particularly near the surface of the strip. This modification retains the bioreceptors (antibodies) close to the surface of the strips, and thus further increasing the density of selectively attached gold nanoparticles (AuNPs) in the top part of the membrane, in the test line area, only when the sample is positive. This effect boosts in average a 36.6% the sensitivity of the LFs. The optical measurements of the LFs were carried out with a mobile phone camera whose imaging resolution was improved by attaching microscopic lens on the camera objective. The characterization of CNF into paper and their effect was analyzed using atomic force microscope (AFM) and scanning electron microscope (SEM) imaging techniques.

Production and characterization of starch‐based films reinforced by ramie nanofibers (Boehmeria nivea)

ABSTRACTIn this study, the use of cellulose nanofibers from ramie, a plant species with important characteristics of reinforcement, was investigated in the production of bio‐based polymer films. A central composite rotatable design was applied to produce the films, analyze the effects of cassava starch, glycerol, and nanofibers content on their properties, obtain mathematical models, response surface plots, and determine an optimum composition. The films produced were characterized by mechanical properties, water vapor permeability (WVP), solubility, and opacity. Microstructure and thermal behavior were also evaluated. The ramie nanofibers content had a positive effect on mechanical and barrier properties, as it increased tensile strength by 207.9%, and decreased WVP and solubility by 52.9 and 72.9%, respectively. Furthermore, the obtained films exhibited homogeneous and cohesive structures, which encourages the use of ramie nanofibers as a reinforcement material in the production of green plastics. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47919.

Use of Cellulose Nanofibers as an Electrode Binder for Lithium Ion Battery Screen Printing on a Paper Separator.

Water-based inks were formulated using cellulose nanofibers as a binder in order to directly front/reverse print lithium ion cells on a paper separator. Moreover, the high cohesion of electrodes as provided by cellulose nanofibers allowed for the embedding metallic current collectors in the electrodes during the printing stage, in order to develop a one-step printing and assembling process. Positive and negative inks based on LiFePO4, or graphite, respectively, and cellulose nanofibers, displayed rheological properties complying with a variety of printing processes, as well as with screen printing. Printed cells exhibited high electrical conductivity and adhesion between current collectors and inks, i.e., up to 64 ± 1 J/m2. Electrochemical cycling tests at C/10 showed a reversible capacity during the first cycle of about 80 mAh/g, which slightly decayed upon cycling. Preliminary results and assembling strategies can be considered as promising, and they represent a quick solution for the manufacturing of lithium ion batteries. Work is in progress to improve these processing issues and the cycling performances of Li-ion cells.

Banana starch nanocomposite with cellulose nanofibers isolated from banana peel by enzymatic treatment: In vitro cytotoxicity assessment

The potential use of cellulose nanofibers (CNFs) as a reinforcing agent in banana starch-based nanocomposite films was investigated. CNFs were isolated from banana peel (Musa paradisiaca) by enzymatic hydrolysis. Banana starch-based nanocomposite films were prepared with CNFs using the casting method. CNFs effect on cell viability and on nanocomposite films properties’ was investigated. The cytotoxicity of CNFs was assessed on Caco-2 cell line. CNFs were not cytotoxic at 50–2000 μg/mL. However, CNFs above 2000 μg/mL significantly decreased cell viability. Topography analysis showed that the incorporation of CNFs modified the film structure. The nanocomposites exhibited a complex structure due to strong interactions between CNFs and starch matrix, promoting a remarkable improvement on mechanical and water barrier properties, opacity and UV light barrier compared to the control film. CNFs can offer a great potential as reinforcing material for starch-based nanocomposite films, producing a value-added food packaging from a waste material.