Incorporation Of Cellulose Nanofibrils Research Articles

Direct Ink Writing 3D Printing Elastomeric Polyurethane Aided by Cellulose Nanofibrils.

3D printing of a flexible polyurethane elastomer is highly demandable for its potential to revolutionize industries ranging from footwear to soft robotics thanks to its exceptional design flexibility and elasticity performance. Nevertheless, conventional methods like fused deposition modeling (FDM) and vat photopolymerization (VPP) polyurethane 3D printing typically limit material options to thermoplastic or photocurable polyurethanes. In this research, a water-borne polyurethane ink was synthesized for direct ink writing (DIW) 3D printing through the incorporation of cellulose nanofibrils (CNFs), enabling direct printing of complex, monolithic elastomeric structures at room temperature that can maintain the designed structure. Additionally, a solvent-induced fast solidification (SIFS) method was introduced to facilitate room-temperature curing and enhance mechanical properties. The 3D-printed WPU structures demonstrated strong interfacial adhesion, exhibiting high ultimate tensile strength of up to 22 MPa and an elongation at break of 951%. The 3D-printed WPU structures also demonstrated outstanding resilience and durability, capable of enduring more than 100 cycles of compression and tension as well as withstanding vehicle crushing and heavy lifting. This method also shows suitability for 3D printing complex structures such as a vase and an octopus.

Cellulose nanofibrils as rheology modifier and fluid loss additive in water-based drilling fluids: Rheological properties, rheological modeling, and filtration mechanisms

This study aims to improve the rheological and filtration properties of water-based drilling fluids (WDFs) by using cellulose nanofibrils (CNFs), which are the critical parameters in drilling operation. Results showed that the incorporation of CNFs in WDFs effectively improved the rheological and filtration properties. The lathy and flexible CNFs was entangled with bentonite (BT) to form the intertwined CNFs-BT network structure in WDFs, leading to an enhanced viscosity, gel behavior, and temperature stability of WDFs. WDFs containing CNFs showed the superior rheological properties, including the yield stress, anti-deformation capacity and structural restructuring capacity, suggesting an increased capacity to transport the cuttings to the surface. The excellent shear-thinning behavior was due to the orientation movement of CNFs along the shear force. Moreover, the nanosized CNFs resulted in the low permeable filter cakes, leading to less fluid loss volume and final filtration rate. We revealed the fundamental insights into the rheological and filtration properties of WDFs containing CNFs, paving the way for the application of new eco-friendly drilling fluid. Data availabilityData will be made available on request.

Internal bonding microstructures characterisation between plant nanocellulose and concrete mortar mixtures for indoor Radon-222 gas emanation reduction

• CNF crystallinity index fosters by high frequency ultrasonication. • Great CNF dissemination enhances mechanical strength of the composite brick. • CNF significantly impact internal porosity nanonization of the composite brick. • Tiniest internal porosity observed on 40 mL kenaf CNF composite brick. • Lowest 222 Rn concentration emanated from 40 mL oil palm CNF composite brick. Radon-222 ( 222 Rn) is a natural radioactive gas produced by the radium-226 ( 226 Ra) decay process, which is part of the uranium-238 ( 238 U) decay series. 222 Rn gas can penetrate into the respiratory system during the inhalation process and have an indirect effect on lung tissues due to energetic alpha particles. Brick is a common building material that consists of rock, water, and sand. It is the most prevalent source of 222 Rn gas emanation to humans in an indoor building environment. To reduce indoor 222 Rn gas emanation, kenaf and oil palm cellulose nanofibrils (CNF) were mixed into bricks in certain ratios and acted as liquid fillers. CNFs were produced by using chemical pulping, bleaching, and ultrasonic techniques. Ten composite bricks with different ratios of CNF and one control brick were fabricated by following Malaysia Standard (MS 7.6:1972). The characterization of CNF was done using Fourier Transformed Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM). The Brunauer-Emmett-Teller (BET) was used to analyse the internal porosity and surface area of the fabricated bricks. 222 Rn concentrations in the bricks and humidity inside the prototype Perspex box were recorded using the Radon Sentinel Monitor Model 1030. The surface areas for control brick, 40 mL kenaf, and oil palm CNF composite bricks are 3.4473 m 2 /g, 4.449 m 2 /g, and 4.9025 m 2 /g, respectively. Meanwhile, pore sizes for control brick, 40 mL kenaf and oil palm CNF composite bricks are 2.92 nm, 0.347 nm and 2.27 nm, respectively. The highest 222 Rn concentration was measured in control brick, which is 3.77 pCi/L, followed by 40 mL kenaf CNF brick and 40 mL oil palm CNF brick, with readings of 1.4 pCi/L and 0.93 pCi/L. The incorporation of CNFs has the ability to reduce 222 Rn emissions while increasing the physical strength of the bricks.

Tailoring structural properties, mechanical behavior and cellular performance of collagen hydrogel through incorporation of cellulose nanofibrils and cellulose nanocrystals: A comparative study

Physically cross-linked collagen hydrogel is a desirable scaffold for tissue engineering applications especially where 3D cell encapsulation is considered. To overcome its shortcomings such as weak mechanical properties and also provide additional benefits, nanofiller reinforcement could be applied. This study was conducted to compare physical properties and cellular performance of physically cross-linked collagen hydrogel reinforced with cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs). Addition of both nanofillers drastically changed the hydrogel properties depending on the type and concentration. As a general trend, both CNCs and CNFs resulted in reduction in gelation time, enhancement in compressive strength, increase in swelling ratio, decrease in weight loss and improvement of injectability. The highest impact for CNCs was achieved when 5 % was applied, while the maximum impact for CNFs was observed for 3 % content (related to the collagen solid weight). By comparing two types of nanocellulose, CNCs showed higher impact on all properties. In-vitro cell compatibility with fibroblasts showed that CNFs did not adversely affected the viability and morphology of the cells while the CNCs improved cell viability and developed more elongated cell morphology.

Development of cellulose nanofibrils reinforced polyvinyl alcohol films incorporated with alizarin for intelligent food packaging

SummaryVisual pH‐sensing films were fabricated using cellulose nanofibrils (CNF) reinforced polyvinyl alcohol (PVA) and alizarin. The relationships between the ratio of PVA: CNF hydrogel (2:1, 1:1, 1:2) and the physical properties and colour response efficiency of indicator films were investigated. Fourier transform infrared spectroscopy of films evidenced alizarin and CNF was properly incorporated by physical interaction. A new weak X‐ray diffraction peak appeared at 2θ = 22.4°, which was affected by the incorporation of CNF. The increase in the CNF content induced enhancements of thermal stability, tensile strength, water contact angle and colour sensitivity of the indicator films. The colourimetric films had a higher sensitivity to discolouration when exposed to acidic vapours than alkaline vapours. The films presented a remarkable colour change varied from purple in alkaline condition to yellow in acidic condition. Therefore, this colourimetric film can be used as a volatile acid sensor for intelligent packaging.

Cellulose nanofibrils reinforced xylan-alginate composites: Mechanical, thermal and barrier properties

Cellulose nanofibrils (CNFs) can be used as an effective reinforcement material for biopolymer films intended for food packaging applications. The aim of this study was to improve the mechanical and barrier properties of xylan-alginate films by incorporating CNFs into the xylan-alginate matrix. CNFs was produced from maize stalk waste residues through a combination of chemical and mechanical treatment. The CNFs was incorporated into the xylan-alginate matrix between 1 and 10 wt%. The suitability of the CNFs reinforced composite films for food packaging applications was investigated by testing the mechanical, thermal and optical properties as well as the moisture sorption, solubility and water vapour permeability of the films. The CNFs produced had fibre diameters between 10 and 80 nm and transmission electron microscopy images showed that the CNFs were highly entangled hence forming a web like structure. It was found that the incorporation of CNFs into the xylan-alginate matrix increased the tensile strength and Young's modulus of the films. The incorporation of CNFs improved the WVP of the films but did not show any significant effect on the thermal properties of the films.

Preparation and characterization of tannin-based adhesives reinforced with cellulose nanofibrils for wood bonding

AbstractAdhesives based on vegetable tannins are already a reality in the market. However, their use is still limited due to their low mechanical resistance and weak humidity resistance. Cellulose nanofibrils (CNFs) are being used as reinforcing materials in various composites, resulting in an improvement of mechanical proprieties in general. The objective of this work was to evaluate the incorporation of CNFs in adhesives made of tannins obtained from the Angico tree (Anadenanthera peregrine). Concentrations of nanofibrils at 1, 5, and 10% were added to the adhesives on a dry basis. Tests of viscosity, pH, solids content, and gel time were performed to determine the physical proprieties of the adhesives. The Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Raman spectra measurements were also determined to understand the interaction between tannins and CNFs. Thermogravimetric analyses (TGA) were carried out to determine the thermal resistance of the composite. The FTIR and Raman characterization identified some differences in the peaks in the chemical composition of the adhesives with different percentages of CNFs. The adhesives showed no different decomposition in the thermogravimetric analyses. The shear strength in the glue line of the adhesive with 5% of CNFs inToona ciliatawoods was determined. Among all the adhesives analyzed, the one with 5% of CNFs produced an improvement in the mechanical resistance and humidity resistance on the glue line.

Application of Cellulose Nanofibrils Isolated from an Agroindustrial Residue of Peach Palm in Cassava Starch Films

Cellulose nanofibrils (CNF) isolated from the external sheaths of palm peach (Bactris gasipaes) were evaluated as improvers of several characteristics of cassava starch films. The cellulosic material of 10 to 30 nm diameter was produced by mechanic defibrillation. All films were characterized by scanning electron microscopy, thermal analysis, water vapor permeability (WVP), Fourier transform infrared spectroscopy, physical characterizations (solubility, humidity, water activity, thickness, tensile strength and elongation) and optical analysis. The incorporation of CNF as reinforcement caused changes in all properties analyzed, thus differing from the control film (without cellulosic reinforcement). Physical reinforcement was the main effect observed in films containing CNF, according to the mechanical resistance and permeability analyses. Furthermore, such analyses confirmed the increase in tensile strength in 306% and reduction in 26% of WVP for films containing 5.37% nanofibrils, when compared to the control. Higher opacity was verified as more CNF was added to the filmogenic matrix, as a result of the dispersion of light by nano-sized fibrils. No variations in the thermal profiles occurred in films containing CNF or not. Spectroscopic data revealed a possible crosslinking formation between starch and CNF, which can influence positively the tensile strength of such films.

High-Performance Styrene-Butadiene Rubber Nanocomposites Reinforced by Surface-Modified Cellulose Nanofibers.

Styrene-butadiene rubber (SBR) is widely used in the tire, footwear, and belt industries. SBR products contain a high content of carbon black, which is hazardous to human health and the environment. The goal of this study is to investigate the potential of using bio-based cellulose nanofibrils (CNFs) as a replacement for carbon black under simulated industrial formula/processing conditions. CNFs were surface-modified using five different reagents to have either −SH or −C=C functional groups grafted onto their surfaces. Vulcanized SBR sheets reinforced with pristine CNFs, and the five functionalized CNFs were prepared and their properties were tested and compared with those of industrial SBR containing carbon black. All the CNFs, pristine or modified, demonstrated higher reinforcing efficiencies (property increase/amount of reinforcement) than carbon black. The modified CNFs showed even higher reinforcing efficiencies than the pristine ones because of the former’s better dispersion and stronger interfacial bonding. The −SH and −C=C functional groups reduced the hydrophilicity of CNFs and allowed chemical linkages between CNFs and SBR to be established during vulcanization. Solvent (toluene) resistance of the rubber was also improved after the incorporation of CNFs because of the barrier effect of the nanofibers and the restrained SBR chain mobility. The latter also led to reduced rubber damping. Although CNFs provide much stronger reinforcement than carbon black, going forward, SBR/CNFs/carbon black hybrid nanocomposites can also be developed to offer tailorable property combinations that meet different application requirements.

Rapid self-healing, stretchable, moldable, antioxidant and antibacterial tannic acid-cellulose nanofibril composite hydrogels

Here, we designed a self-healing composite hydrogel with antioxidant and antibacterial activities by using cellulose nanofibrils (CNF) and tannic acid (TA) as functional additives. Excellent mechanical stability, moldability, stretchability and rapid self-healing ability without any external intervention were realized in one system due to the combined dynamic borate ester bonding between polyvinyl alcohol-borax (PB) and multi-hydrogen bonding between different components. The rheological measurements indicated the incorporation of CNF and TA to PB system substantially affected the viscoelasticity of hydrogels. The unique antioxidant and antibacterial properties were achieved due to the complexation of TA. These high performance multifunctional hydrogels opens a window for a broad application in the field of smart devices and surface engineering.

Structure-Property Relationships in Hybrid Cellulose Nanofibrils/Nafion-Based Ionic Polymer-Metal Composites.

Herein, we report the production of ionic polymer-metal composites (IPMCs) hybridized with cellulose nanofibrils (CNF) as a partial substitute for Nafion®. The aim is not only to reduce the production cost and enhance respective mechanical/thermal properties but also to bestow a considerable degree of biodegradability to such products. Formulations with different CNF/Nafion® ratios were produced in a thin-film casting process. Crack-free films were air-dried and plated by platinum (Pt) through an oxidation-reduction reaction. The produced hybrids were analyzed in terms of thermal stability, mechanical and morphological aspects to examine their performance compared to the Nafion-based IPMC prior to plating process. Results indicated that films with higher CNF loadings had improved tensile strengths and elastic moduli but reduced ductility. Thermogravimetric analysis (TGA) showed that the incorporation of CNF to the matrix reduced its thermal stability almost linearly, however, the onset of decomposition point remained above 120 °C, which was far above the temperature the composite membrane is expected to be exposed to. The addition of a cross-linking agent to the formulations helped with maintaining the integrity of the membranes during the plating process, thereby improving surface conductivity. The focus of the current study was on the physical and morphological properties of the films, and the presented data advocate the potential utilization of CNF as a nontoxic and sustainable bio-polymer for blending with perfluorosulfonic acid-based co-polymers, such as Nafion®, to be used in electroactive membranes.

Thermal stability of cellulose nanomaterials and their composites with polyvinyl alcohol (PVA)

This study investigates the thermal stability of composites composed of polyvinyl alcohol (PVA) reinforced with biodegradable fillers: cellulose nanocrystals (CNC) or cellulose nanofibrils (CNF). Combinations of PVA with CNC and PVA with CNF at 2, 4, 6, and 8 % cellulose by weight underwent several different thermogravimetric analysis (TG) heating programs—constant heating rate, isothermal, and high resolution with a dynamic heating rate. The starting materials (PVA pellets, PVA film, aqueous CNC at 11.8 % solids, and aqueous CNF at 3 % solids) were also tested in the TG after drying. Temperatures at the onset of degradation and at maximum degradation for the principal pyrolysis stage were quantified. Kinetic parameters (activation energy, pre-exponential factor) were calculated using the Flynn–Wall–Ozawa (FWO) method. CNC or CNF incorporation in the PVA matrix did not markedly shift temperatures at the onset of degradation or at maximum degradation for the major stage of pyrolysis, compared to neat PVA. However, the inclusion of nanocellulose lowered the maximum rate of degradation, with larger reductions at higher filler contents. A larger portion of the composites’ original mass remained intact following the major degradation peak. Incorporation of CNF in composites with PVA produced films with activation energies higher than the activation energy of neat PVA film.

Biodegradable Nanocomposite Films Based on Sodium Alginate and Cellulose Nanofibrils.

Biodegradable nanocomposite films were prepared by incorporation of cellulose nanofibrils (CNF) into alginate biopolymer using the solution casting method. The effects of CNF content (2.5, 5, 7.5, 10 and 15 wt %) on mechanical, biodegradability and swelling behavior of the nanocomposite films were determined. The results showed that the tensile modulus value of the nanocomposite films increased from 308 to 1403 MPa with increasing CNF content from 0% to 10%; however, it decreased with further increase of the filler content. Incorporation of CNF also significantly reduced the swelling percentage and water solubility of alginate-based films, with the lower values found for 10 wt % in CNF. Biodegradation studies of the films in soil confirmed that the biodegradation time of alginate/CNF films greatly depends on the CNF content. The results evidence that the stronger intermolecular interaction and molecular compatibility between alginate and CNF components was at 10 wt % in CNF alginate films.

Creep behavior of starch-based nanocomposite films with cellulose nanofibrils.

Nanocomposite films were successfully prepared by incorporating cellulose nanofibrils (CNFs) from sugar beet pulp into plasticized starch (PS) at CNFs concentration of 5-20%. The storage (G') and loss (G″) moduli, creep and creep-recovery behavior of these films were studied. The creep behavior of these films at long time frame was studied using time-temperature superposition (TTS). The CNFs were uniformly distributed within these films up to 15% of CNFs. The PS-only and the PS/CNFs nanocomposite films exhibited dominant elastic behavior. The incorporation of CNFs increased both the G' and G″. The CNFs improved the creep resistance and reduced the creep recovery rate of the PS/CNFs nanocomposite films. TTS method was successfully used to predict the creep behavior of these films at longer time frame. Power law and Burgers model were capable (R(2)>0.98) of fitting experimental G' versus angular frequency and creep strain versus time data, respectively.

Biodegradable poly(vinyl alcohol) foams supported by cellulose nanofibrils: processing, structure, and properties.

In order to capture savings in energy and ambitious environmental targets, biodegradable composite foams of poly(vinyl alcohol) (PVA) supported by cellulose nanofibrils (CNF) were prepared through unidirectional freeze-drying technology. Effects of the content of CNF, the solid content of the precursor suspension, and the quenching temperature on the microstructure and properties of the composite foams were investigated by scanning electron microscopy (SEM), compressive testing, X-ray diffraction (XRD) analysis, water uptake, and biodegradation tests. Results show that the incorporation of CNF preferably at a weight ratio of 30 wt % greatly enhanced the mechanical strength and modulus, energy absorption, water resistance, and dimensional stability of the composite foams because of the rigid and semicrystalline nature of CNF as well as regular and compact pore structures. Furthermore, the biodegradation tests performed in a simulated aerobic compost environment suggested that the involvement of CNF significantly accelerated the pace of biodegradation of the composite foams. Hence, we provided some meaningful information on the biomimetic cellular composite foams with controllable morphs and properties by varying the freeze-drying process and composition.

Mechanically robust, flame-retardant and anti-bacterial nanocomposite films comprised of cellulose nanofibrils and magnesium hydroxide nanoplatelets in a regenerated cellulose matrix

Nanocomposite films consisting of cellulose nanofibrils (CNFs), magnesium hydroxide nanoplatelets (MHNPs) and regenerated cellulose were prepared via simple blending and casting processes. The CNFs were obtained from bamboo pulp by ultrasonic treatment coupled with high shear homogenization. The morphology, structure and properties of the nanocomposite films were comprehensively analyzed using various characterization techniques, including the scanning electron microscope, digital microscope, limiting oxygen index (LOI), micro-scale combustion calorimetry, antibacterial assays, tensile testing, etc. When the MHNP content was optimized to 30 wt%, the nanocomposite film exhibited the best overall properties. The LOI of the composite film increased from 20.0 (0 wt% MHNPs) to 32.7 (30 wt% MHNPs), making it a flame-retardant material in air. In addition, the film containing 30 wt% MHNPs showed excellent antibacterial activity. However, the increase in MHNP content would result in gradual deterioration of the films’ mechanical properties. However, the incorporation of CNFs could significantly suppress this trend. The present work provided a promising pathway for manufacturing multifunctional and high-performance cellulose-based composite films, which were potentially useful for a variety of packaging materials, especially in the biomedical and food packaging fields.