Wood Cellulose Fibers Research Articles

Prediction of the dynamic pressure drop of filter media loaded with water mists based on the deposited droplet mass distributions and pore network model

Predicting the pressure drop of a filter is necessary, especially regarding the jump in the dynamic pressure drop of a filter without pre-filters when clogged by rain or fog droplets. However, the efficient prediction method for the pressure drop in cylinder filters loading with water mists in the pore network faces limitations due to the high requirements for microscopic images of materials and the need to consider for the increasing holding droplet capacity of filters. In this study, a systematic method that takes into account the distributions of the deposited droplet mass within the water-absorbed filter medium layers in the pore network model (PNM) was developed. The pore geometry and distributions were determined from 2D microstructure images, and the dynamic deposited droplet mass and water-absorbing capacity of fibers were combined with the changing saturation to optimize the PNM for calculating the dynamic pressure drop of the filter media. Specifically, the empirical equation of the self-defined equivalent single fiber filtration efficiency (ESFFE) describes the relationship between the changing single fiber filtration efficiency and the deposited droplet mass. The optimized PNM is suitable for predicting the behavior of bibulous wood cellulose fiber filter media. The dynamic pressure drop shows a slight increase before surging, following the typical “channel and jump” model. Although the calculations deviate slightly from the experimental results with 25 % deviations, this systematic method effectively predict the jump in pressure drop of the tested filter medium. Therefore, this systematic method for predicting pressure drop of filters holds promise in anticipating unsafe pressure drop jumps in filters installed in coastal areas.

Bonding Wood via Cellulose Aqueous Solution as Cell Wall Adhesive

The size of the wood plays a crucial role in determining its ultimate application. In order to break through the dimensions of natural wood, multiple pieces of wood are often bonded together with adhesives to form larger sizes. The physical and chemical properties of adhesives are different from those of natural wood, and this difference often leads to failure of the adhesive bonding interface. Herein, an aqueous solution of dissolved cellulose has been used as an adhesive to bond wood. The regenerated cellulose produced by recrystallization combines the wood fibers that originally existed on the wood surface cell wall. The resulting bonding wood interface consists of densely packed regenerated cellulose and wood cellulose fibers, which possess strong hydrogen bonds and physical entanglements. The shear strength has surpassed those of typical bio‐based adhesives and commercial adhesives. The same composition as natural wood endows this bonding interface with physical and chemical properties similar to natural wood such as weatherability. Bonding wood with this cellulose aqueous solution as an adhesive reduces the dependence on petrochemical‐based adhesives, and this facile and pressureless bonding strategy offers a promising route to manufacture sustainable wood composites with robust bonding interfaces.

Regenerated cellulose properties tailored for optimized triboelectric output and the effect of counter-tribolayers

Cellulose has shown great potential in the development of green triboelectric nanogenerators. Particularly, regenerated cellulose (R-cellulose) has shown remarkably high output power density but the structural features and key parameters that explain such superior performance remain unexplored. In this work, wood cellulose fibers were dissolved in a LiOH(aq)-based solvent to produce a series of R-cellulose films. Regeneration in different alcohols (from methanol to n-pentanol) was performed and the films’ structural features and triboelectric performance were assessed. Nonsolvents of increased hydrophobicity led to R-cellulose films with a more pronounced (1–10) diffraction peak. An open-circuit voltage (VOC) of up to ca. 260 V and a short-circuit current (ISC) of up to ca. 150 µA were measured for R-cellulose against polytetrafluoroethylene (as negative counter-layer). However, R-cellulose showed an increased VOC of 175% (from 88.1 V) against polydimethylsiloxane when increasing the alcohol hydrocarbon chain length from methanol to n-pentanol. The corresponding ISC and output power also increased by 76% (from 89.9 µA) and by 382% (from 8.8 W m–2), respectively. The higher R-cellulose hydrophilicity, combined with soft counter-tribolayer that follow the surface structures increasing the effective contact area, are the leading reasons for a superior triboelectric performance.Graphic abstract

Cellulose Nanocrystal Preparation via Rapid Hydrolysis of Wood Cellulose Fibers Using Recyclable Molten Ferric Chloride Hexahydrate

Cellulose nanocrystals (CNCs) are clean and sustainable materials that have drawn significant attention in academia and industry because of their unique physicochemical properties. However, realizing economical and environmentally friendly production of CNCs remains a challenge. In this study, we proposed an innovative strategy to fabricate CNCs, which involves the acid hydrolysis pretreatment of wood cellulose fibers using innocuous and recyclable ferric chloride hexahydrate (FeCl3·6H2O). During the molten FeCl3·6H2O treatment, the degree of polymerization (DP) of the cellulose fibers sharply decreased, along with the transformation of cellulose I to cellulose II crystallites. Molten FeCl3·6H2O quickly hydrolyzed cellulose fibers within 5 min at 80 °C, inducing a rapid decrease in the DP from 922 to 196, and the water-insoluble solid (WIS) retention reached 80.1%. CNCs were successfully produced from the mechanical disintegration of the WIS with a low energy input. Hence, the yield of CNCs is consistent with that of the WIS. Interestingly, the CNCs exhibited typical cellulose II crystallites, which were significantly different from those of the cellulose feedstock (cellulose I). Detailed characterization revealed that the CNCs had tunable number-averaged heights of 10.4–26.9 nm and high thermal stability (a maximal weight loss temperature of 327 °C). Most notably, FeCl3·6H2O was easily recycled from the hydrolysate after hydrolysis, with a high recovery of 94.0–94.5 wt %, using simple concentration and crystallization technologies. Thus, this study proposes a novel production technology for CNCs that is both economical and eco-friendly, providing new ideas for clean and large-scale production of CNCs.

Active Food Packaging Based on Coconut Coir Pulp with the Addition of Antimicrobial Oleoresin Substance from Ginger Dregs

The development of food packaging innovations is ongoing, from materials to varied shapes and designs. Paper packaging is one of the various types of packaging that are widely used as an alternative to plastic packaging. However, the high use of paper can damage the environment, such as deforestation and reduction of green land. Alternative raw materials for making paper need to be studied further, and the addition of active ingredients will be an added value compared to ordinary paper packaging. This narrative review will examine the potential of active food packaging from coconut fiber and the addition of ginger pulp oleoresin. Coconut coir is waste from coconut production that is underutilized, while 25% of one coconut is produced from waste in the form of coconut coir. Coconut coir can replace wood's cellulose fibers to manufacture biodegradable, environmentally friendly paper. Ginger flesh contains oleoresin as an antimicrobial agent. Oleoresin is a mixture of essential oils and resins obtained by extraction. Adding these antimicrobial substances will produce active packaging that effectively handles and prevents contamination and microbial growth in food. Therefore, paper made from coconut coir pulp with the addition of oleoresin has the potential to be developed into active food packaging as an effort to conserve the environment and utilize waste.

Electrically Conductive Biocomposites Based on Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and Wood-Derived Carbon Fillers

In this paper, biobased carbons were used as fillers in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). The mechanical and electrical properties of these 100% biocomposites were analyzed. First, biocarbons were prepared from wood dust and cellulose fibers using carbonization temperatures ranging 900–2300 °C. XRD revealed significant improvements of the graphitic structure with increasing temperatures for both precursors, with slightly higher ordering in wood-dust-based carbons. An increase of the carbon content with continuous removal of other elements was observed with increasing temperature. The carbonized cellulose fiber showed an accumulation of Na and O on the fiber surface at a carbonization temperature of 1500 °C. Significant degradation of PHBV was observed when mixed with this specific filler, which can, most probably, be attributed to this exceptional surface chemistry. With any other fillers, the preparation of injection-molded PHBV composites was possible without any difficulties. Small improvements in the mechanical performance were observed, with carbonized fibers being slightly superior to the wood dust analogues. Improvements at higher filler content were observed. These effects were even more pronounced in the electrical conductivity. In the range of 15–20 vol.% carbonized fibers, the percolation threshold could be reached, resulting in an electrical conductivity of 0.7 S/cm. For comparison, polypropylene composites were prepared using cellulose fibers carbonized at 2000 °C. Due to longer fibers retained in the composites, percolation could be reached in the range of 5–10 vol.%. The electrical conductivity was even higher compared to that of composites using commercial carbon fibers, showing a great potential for carbonized cellulose fibers in electrical applications.

Experimental Investigations of the Resistance Performance of Commercial Cylinder Filters and Effect Factors under Humid Airflows

Experiments were performed to summarize the variations in the resistance of commercial cylinder filters applied in the air intake filtration systems of gas power plants under humid airflows. Seven clean cylinder filters composed of various materials (including synthetic, wood cellulose, nanofibers, and polyester fibers) are subjected to the airflow containing water mist. The results show that the resistance of polyester fiber filters and synthetic fiber filters was increased by the large droplets on the surface of the hydrophobic filter media when loaded with water droplets generated. Several factors including the water-holding capacity (WHC) of fibers, low filtration efficiency, and the unique composite structure of nanofiber filters media can limit the "Pjump" of cylinder filters, increasing the mass of water droplets loaded or avoiding the high resistance. By contrast, the resistance trends of nanofiber media increased significantly from the initial resistance when singly subjected to airflows with water mist at 5.96 g m-3 and 90% relative humidity, differing from the nanofiber filter whose resistance tends to stabilize. These differences were primarily caused by the pleat-free structures and the install directions of the nanofiber medium in the clamp, indicating differences in the filtration performance between the filter medium and its filters.

Wood-cellulose-fiber-based functional materials for triboelectric nanogenerators

Wood cellulose fiber is often used as a substrate or triboelectric material in the construction of triboelectric nanogenerators (TENGs) because of its unique optical and mechanical properties, as well as its potential for chemical modification and reconstruction. The design of wood cellulose fiber as an advanced functional material based on its advantages will be of great significance for green and large-scale self-powered energy equipment. This work highlights the research progress in wood cellulose fiber applications in the TENG field. The unique molecular structural features of wood cellulose fiber are briefly introduced, the structural characteristics of wood cellulose fiber and related derivative materials are considered, and the application scenarios and advantages of wood cellulose fiber in TENGs are summarized. The factors affecting the triboelectric performance of wood cellulose fiber and the research progress of wood-cellulose-fiber-related materials as TENG friction layer and substrate materials are systematically elaborated. Furthermore, the structural design and performance optimization of TENGs based on wood cellulose fiber are summarized, and its application status in energy harvesting, sensor networks, and wearable electronic devices, are introduced. Lastly, the challenges faced in the future developments of wood-cellulose-fiber-based TENGs are discussed, thereby guiding researchers to the large-scale application of wood-cellulose-fiber-based TENGs. • Applications and advantages of wood cellulose fiber in TENG are introduced by analyzing their structural characteristics. • The structural design and performance optimization of TENG based on wood cellulose fiber are summarized. • Challenges and future prospects in the development of wood-cellulose-fiber-based TENG are discussed.

Bio-inspired cellulose reinforced anisotropic composite hydrogel with zone-dependent complex mechanical adaptability and cell recruitment characteristics

Articular cartilage, due to its avascular nature and the low cell density, is hard to regenerate once damaged, thus requiring surgical intervention. Natural cartilage exhibits a complex anisotropic feature with nonlinear and viscoelastic mechanical properties owning to complicated architecture making it attractive to mimic the structure. Here, we demonstrate a three-zone composite hydrogel with superficial, middle and deep zones incorporating into cellulose fabric, cellulose nanofiber and wood cellulose fiber respectively to prepare a stack layout composite hydrogel inspired by cartilage architecture with zone-dependent mechanical properties. The results indicate that the three-zone cellulose reinforced polyethylene glycol-based composite hydrogel demonstrates hydrogel creates native-like articular cartilage with zone-dependent, nonlinear and viscoelastic mechanical properties. The compressive moduli of the superficial, middle and deep zones are 298 kPa, 182 kPa and 9.8 MPa respectively, and the middle zone possess obvious nonlinear features. Furthermore, the highly aligned wood frame channels endow deep zone with nutrition and cell transport behaviors which are beneficial to the process of cartilage regeneration. Therefore, the bio-inspired three-zone composite hydrogel has a promising potential application for cartilage repair.

Overexpression of the bamboo sucrose synthase gene (BeSUS5) improves cellulose production, cell wall thickness and fiber quality in transgenic poplar

In plants, sucrose synthase (SUS, EC 2.4.1.13) is widely considered a multifunctional protein involved in modulating sink strength, cellulose biosynthesis, and carbon partitioning. However, supporting genetic evidence regarding the role of SUS from bamboo in fiber development is lacking. Here, we obtained transgenic poplar lines overexpressing the bamboo BeSUS5 gene and conducted functional analysis. We found that overexpression of BeSUS5 enhanced the activity of SUS and significantly promoted the growth of the plants, especially xylem growth. In BeSUS5 overexpressed poplar plants, the total soluble sugar (TSS) and starch contents were decreased in leaves, while the cellulose content was increased in stems, indicating that overexpression of BeSUS5 might enhance the partitioning of carbon to cellulose in poplar. Consistent with these results, the expression of cellulose biosynthesis and phloem loading–related genes, such as cellulose synthase (CesA7), KORRIGAN (KOR), and sucrose transporter (SUT1), was upregulated in transgenic plants. As a result, transgenic poplars displayed not only an increase in cell wall thickness and cell wall crystallinity but also an altered stem fiber phenotype. Taken together, our results imply the vast potential of BeSUS5 for the genetic improvement of wood cellulose production and fiber quality.

Production of sustainable wood-plastic composites from the nonmetals in waste printed circuit boards: Excellent physical performance achieved by solid-state shear milling

As a byproduct of electronic waste, the accumulated millions of tons of nonmetals from waste printed circuit boards (referred to hereinafter as NPCB) have caused severe environmental issues. Here, we report a novel method for the production of wood composites reinforced by NPCB via a solid-state shear milling (S3M) process. The S3M pretreatment successfully exfoliated NPCB into single glass fibers with a high aspect ratio. Hemicellulose and lignin were liberated from the surface of the wood cellulose fibers, and the size was reduced to a submicron level. Both optical and electron microscopy revealed that the wood composites prepared by the S3M process exhibited excellent filler dispersion and excellent interfacial adhesion between the filler and the polymer. This NPCB-reinforced wood composite was thermally stable at temperatures below 200 °C. In addition, the exfoliated NPCB and wood flour provided a well-designed structure that improved the tensile strength of the composite to 32.4 MPa. This wood composite retained a high storage modulus of 616 MPa at 100 °C, expanding the upper service temperature limit for wood composites. The excellent interfacial adhesion and hydrophilic nature of NPCB led to water absorption as low as 0.21%, exceeding the values previously reported for NPCB-reinforced wood composites under the same conditions. Finally, this wood composite also contained negligible organic pollutants and low heavy-metal concentrations, which are far below the regulatory limits for hazardous waste. The above results show that the reuse of NPCB in high-strength wood composites is a promising choice for both resolving environmental pollution and reusing solid waste to create value-added products.

Strongly Improved Mechanical Properties of Thermoplastic Biocomposites by PCL Grafting inside Holocellulose Wood Fibers

Chemical wood cellulose fiber modification is performed with the purpose to improve compatibility and induce nanofibrillation of the fibers during melt compounding of thermoplastic biocomposites. C...

Highly strong and flexible composite hydrogel reinforced by aligned wood cellulose skeleton via alkali treatment for muscle-like sensors

Strong and flexible hydrogels have attracted increasing scientific interest due to their “soft-and-wet”properties, which are similar to those of human soft tissues. In this study, a bioinspired, facile method to fabricate a composite hydrogel with a naturally high-strength skeleton structure that shows comparable mechanical performance to those of muscle, tendons and ligaments is reported. The method includes extracting an aligned cellulose skeleton directly from wood by delignification and then compositing with polyacrylamide (PAM) by in-situ chemical polymerization. During these processes, the natural wood skeleton is well preserved and sufficiently high tensile stress is created along the longitudinal direction (L-direction) of wood cellulose fiber, which leads to a highly anisotropicstructure in the prepared PAM/delignified wood (PDW) hydrogels. Although the aligned cellulose skeleton exhibits an efficient strengthening effect, the obtained PDM hydrogels lack the desired flexibility and are easily broken during the harsh deformations. To achieve flexiblility, a simple alkali treatment was applied to the delignified wood which provided the developed PAM/alkali-treated delignified wood (A-PDM) hydrogels with superflexiblility. As a result, the A-PDM hydrogels show excellent tensile properties with Young’s modulus, tensile fracture strength and elongation of 145.52 ± 2.32 MPa, 16.47 ± 1.40 MPa and 15.99 ± 1.81%, respectively. Such favorable mechanical performance is employed to assemble a muscle-like sensor by incorporating the A-PDM hydrogel with ionic Na2SO4 to detect diverse macro-scale human motions. This study provides a facile strategy for designing strong composite hydrogels with superflexibility, opening an effective route for the development of new wood nanotechnology and various functional wood-derived materials.

Changes to the Contour Length, Molecular Chain Length, and Solid-State Structures of Nanocellulose Resulting from Sonication in Water.

Sonication in water reduced the average contour lengths of nanocellulose prepared from wood cellulose fiber and microcrystalline cellulose. Most of the kinks in the wood cellulose nanofibrils were formed during the initial 10 min of sonication. Fragmentation occurred at the kinks and rigid segments associated with depolymerization during subsequent sonication for 10-120 min, resulting in the formation of cellulose nanocrystals with low aspect ratios. Solid-state cross-polarization magic angle sample spinning 13C-nuclear magnetic resonance revealed that the original crystalline regions of the cellulose were partly transformed to fibril surfaces or disordered regions by both pretreatment and the subsequent fragmentation of molecular chains during sonication. The nanocellulose prepared from microcrystalline cellulose had different fragmentation behavior with regard to molecular chain length following sonication. The results indicated that on average the hexagonal 36 cellulose chain structure formed the cross-section of each wood cellulose microfibril.

Superhydrophobic paper fabricated via nanostructured titanium dioxide-functionalized wood cellulose fibers

Herein, an eco-friendly and straightforward method was provided for the fabrication of superhydrophobic paper from native wood cellulose fibers via in situ hydrolysis of tetraethyl titanate(IV) without any chemical pretreatment. By simply adjusting the amount of acetic acid (HAc), the surface micro/nanomorphology could be well controlled. After papermaking and hexadecyltrimethoxysilane modification, superhydrophobic paper can be easily achieved with static water contact angle of 152.3° (± 1.3°). The paper also possessed good self-cleaning property against contamination and durability toward mechanical damages of finger wiping over 50 cycles as well as excellent oil/water separation, which expands its utility in various paper-based technologies. The whole procedure possesses the advantages of friendly raw material, mild reaction conditions and with no toxic modifier, which hold potential application in cellulose-based superhydrophobic material in large scale.

Wood cellulose fibers reinforced polylactic acid composite: mechanical, thermomechanical characteristics and orientation of fiber

The wood cellulose fiber (WCF) reinforced polylactic acid (PLA) offers cost effectiveness, ease of mass production, short processing time, structural stability, high quality and efficient recyclability. In the study presented orientation of fiber, microstructure and thermomechanical property of composites are beingexamined by using X-ray tomography, scanning electron microscopy (SEM), and dynamic mechanical thermal analysis (DMA). Also, the mechanical properties of WCF–PLA–MAH composites were characterized and analyzed. The results demonstrated that the best outcome of elastic modulus and tensile strength were accomplished at 30%WCF–PLA–3%MAH composite. The DMA result explains that by adding MAH in WCF–PLA as an interfacial coupling agent enhanced the storage modulus and increased the toughness of WCF–PLA composite by decreasing the tanδ peak. X-ray tomography of the PLA/WCF/FB composite shows that the degree of anisotropy is accomplished 25% higher when WCF was 30% in PLA matrix. In addition, the SEM micrograph shows that when MAH was used the interfacial compatibility between the PLA matrix and WCF improved.

Polymer Grafting Inside Wood Cellulose Fibers by Improved Hydroxyl Accessibility from Fiber Swelling.

Chemical modification of wood cellulose fibers is important for tailored wood-polymer interfaces, reduced moisture sorption, and novel grades of chemical wood pulp. The present study shows how the reaction solvent system influences hydroxyl accessibility during chemical fiber modification. Surface initiated ring-opening polymerization of ε-caprolactone from wood cellulose fibers was investigated in a wide range of solvent systems. The hydrogen bond donor strength of the solvent increased graft density and the amount of grafted polycaprolactone (PCL) on the fiber surface, and on nanoscale fibrils inside the fiber. Specifically, the reaction system with acetic acid as a new, green solvent for cellulose grafting increased graft density 24 times compared to bulk polymerization conditions. The results show relationships between solvent properties, hydroxyl accessibility, and grafting results in cellulosic plant fibers. The study clarifies the opportunities provided by controlling the interior of the cellulosic plant fiber cell wall during chemical modification so that the fiber becomes a swollen cellulose nanofibril gel.

Lytic polysaccharide monooxygenases (LPMOs) facilitate cellulose nanofibrils production

BackgroundLytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes that cleave polysaccharides through an oxidative mechanism. These enzymes are major contributors to the recycling of carbon in nature and are currently used in the biorefinery industry. LPMOs are commonly used in synergy with cellulases to enhance biomass deconstruction. However, there are few examples of the use of monocomponent LPMOs as a tool for cellulose fibrillation. In this work, we took advantage of the LPMO action to facilitate disruption of wood cellulose fibers as a strategy to produce nanofibrillated cellulose (NFC).ResultsThe fungal LPMO from AA9 family (PaLPMO9E) was used in this study as it displays high specificity toward cellulose and its recombinant production in bioreactor is easily upscalable. The treatment of birchwood fibers with PaLPMO9E resulted in the release of a mixture of C1-oxidized oligosaccharides without any apparent modification in fiber morphology and dimensions. The subsequent mechanical shearing disintegrated the LPMO-pretreated samples yielding nanoscale cellulose elements. Their gel-like aspect and nanometric dimensions demonstrated that LPMOs disrupt the cellulose structure and facilitate the production of NFC.ConclusionsThis study demonstrates the potential use of LPMOs as a pretreatment in the NFC production process. LPMOs weaken fiber cohesion and facilitate fiber disruption while maintaining the crystallinity of cellulose.

Synthesis of uniform layer of TiO2 nanoparticles coated on natural cellulose micrometer-sized fibers through a facile one-step solvothermal method

Here, a uniform layer of TiO2 nanoparticles coated on the surface of natural micrometer-sized fibers was obtained when using polar wood cellulose fibers as templates and titanium butoxide (Ti(OnBu)4) as precursor through a simple one-step solvothermal method. The final samples were characterized by scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray spectrometer, selected area electron diffraction and X-ray diffraction. The results show the cellulose microfibers were coated with layer of highly crystalline anatase TiO2 nanoparticles whose diameter varies from 5 to 10 nm. Moreover, the resultant TiO2/cellulose composite shows an excellent photocatalytic activity in degrading methyl orange dye.

High-Density Molded Cellulose Fibers and Transparent Biocomposites Based on Oriented Holocellulose.

Ecofriendly materials based on well-preserved and nanostructured wood cellulose fibers are investigated for the purpose of load-bearing applications, where optical transmittance may be advantageous. Wood fibers are subjected to mild delignification, flow orientation, and hot-pressing to form an oriented material of low porosity. The biopolymer composition of the fibers is determined. Their morphology is studied by scanning electron microscopy, cellulose orientation is quantified by X-ray diffraction, and the effect of beating is investigated. Hot-pressed networks are impregnated by a methyl methacrylate monomer and polymerized to form thermoplastic wood fiber/poly(methyl methacrylate) biocomposites. Tensile tests are performed, as well as optical transmittance measurements. Structure-property relationships are discussed. High-density molded fibers from holocellulose have mechanical properties comparable with nanocellulose materials and are recyclable. The thermoplastic matrix biocomposites showed superior mechanical properties (Young's modulus of 20 GPa and ultimate strength of 310 MPa) at a fiber volume fraction of 52%, with high optical transmittance of 90%. The study presents a scalable approach for strong, stiff, and transparent molded fibers/biocomposites.