Wood Pulp Research Articles

Preparation of interwoven structure composite paper via polylactic acid infiltrating fiber network

AbstractCellulose is commonly acknowledged as a sustainable material owing to its abundance and renewability. However, the abundance of hydroxyl groups makes the paper material highly hydrophilic, and the hydrogen bonds between the fibers are easily broken by water, leading to the degradation of mechanical properties. This work details the fabrication of a composite paper comprising interwoven cellulose and polylactic acid (PLA) structures through hot‐pressing and PLA impregnation onto handwritten paper derived from conventional wood pulp fibers as the substrate. The investigation assessed how varying PLA concentrations influenced the overall characteristics of the composite paper, including its morphology, structure, mechanical properties, water absorption behavior, and water contact angle. Experimental results revealed that the composite paper fabricated through our approach exhibited an intertwined structure comprising both PLA and cellulose. With a tensile index reaching 33.24 kN·m/kg and a mere 31.1% loss in tensile index post‐water treatment, the mechanical properties of the composite paper were significantly enhanced due to the robust interfacial compatibility between cellulose and PLA, as well as the adhesive effect of PLA. Furthermore, the composite paper (CP) is easily processable and amenable to thermoforming into paper trays as required, indicative of its potential applications in the packaging industry.

Preparation of PBT@PP-CNC@cellulose wood pulp paper double-layers fuel filtration materials with high efficiency and high dust holding capacity

Preparation of PBT@PP-CNC@cellulose wood pulp paper double-layers fuel filtration materials with high efficiency and high dust holding capacity

Near-infrared spectroscopy and multivariate analysis as real-time monitoring strategy of TEMPO-mediated oxidation of cellulose fibers from different feedstocks

The regioselective oxidation of the primary hydroxyl groups of cellulose, usually mediated by the (2,2,6,6-tetramethylpiperidin-1-yl)oxyl radical (TEMPO), is highly popular in the scientific literature. However, the lack of efficient monitoring techniques imposes a severe limitation to its upscaling. This work involves a portable, user-friendly near-infrared spectroscopy device, optimized preprocessing techniques, and multivariate calibration to quickly estimate the carboxyl group content of modified cellulose (i.e., the extent of the oxidation). For that, bleached pulps from eucalyptus, pine, hemp, and sisal were submitted to TEMPO-mediated oxidation, varying the dosage of spent oxidizer (NaClO) and thus attaining samples of different values of carboxyl group content. These values were related to near-infrared spectra (908–1676 nm) by Partial Least Squares regression, yielding cross-validation coefficients (RCV2) above 0.97 for wood pulps, 0.95 for sisal pulp, and 0.91 for hemp pulp. Based on the residual prediction deviation, the model for each pulp was found to show good predictability. Nonetheless, the overall regression model, comprising the four different materials, was unreliable. In light of this, spectra were submitted to principal components analysis (PCA), hinting that pulps could be classified in terms of their hemicellulose to cellulose ratio. Considering all the statistical parameters, the overall proposal presented here begins with a PCA—Linear Discriminant Analysis model to classify the sample by its fiber type, subsequently selecting a specific regression model for that class. Overall, the presented models in this work allow the determination of the extent of oxidation of different cellulosic feedstocks, expressed as carboxyl content, in a fast and simple approach using a benchtop near-infrared equipment.

Evaluation of Recycled Paperboard Properties and Characteristics

Paperboard boxes represent a sought-after class of packaging products, where the use of recycled fibers offers a cost-effective and environmentally friendly alternative to virgin fibers. The presence of a significant proportion of recycled fibers in the paperboard leads to a number of limitations associated with the deterioration of its characteristics. In this study, the properties of coated and uncoated paperboards containing recycled fibers, wood pulp, and virgin cellulose fibers were investigated using a laboratory sample of paperboard produced from 100% recycled fibers without any chemical additives for comparison. Properties such as smoothness, bulk density, absorbency, and tensile strength, as well as colorimetric characteristics, were determined for the recycled paperboards; for the latter test, charts were printed using inkjet printing and UV-curable inks. Whiteness was calculated by three formulae (CIE, Berger, and Stensby), and all the paperboards had a relatively low whiteness (not exceeding 90 CIE), with a yellowish tint due to recycled fibers and mechanical pulp in the composition. The absence of optical brightening agents in the paperboards was experimentally confirmed. The color gamuts of the paperboards were in direct ratio to their whiteness, with the highest ones demonstrated by the coated paperboards. Color reproduction, according to the tone value increase curves, also depended on the whiteness. Uncoated paperboards demonstrated smaller color shifts than the coated ones, with the greatest increase in tone for yellow color. Coated recycled paperboards are suitable for packaging printing under the same conditions as virgin fiber boards, while uncoated boards are the recommended choice for digital printing with UV inks.

Development of a beverage carton closure cap based on 100% wood pulp fibres

Single-use plastic products have been identified as an environmental challenge. When such products are not recycled, they may end up in nature and thus cause, e.g., marine littering. Thermoformed wood pulp fibre products are gaining more interest to replace fossil plastic products. However, beverage caps made of wood pulp fibres are challenging due to the hygroscopic nature of wood fibres, i.e., they absorb water, deform and loose functionality. Hence, the purpose of this study was to develop a fibre-based beverage cap that could replace plastic tethered cap systems. Both unbleached and bleached Kraft pulp and chemo-thermo-mechanical pulp (CTMP) fibres were tested in thermoforming trials, using tailor-made metal moulds. The results showed that Kraft pulp fibres formed denser structures, with more limited water absorption, compared to CTMP. The mechanical properties of thermoformed specimens were suitable for the application, i.e., the strength, modulus and elongation were between 32 and 36 MPa, 4–4.9 GPa and 1.6–1.9%, respectively, depending on the type of pulp fibre. Additionally, in order to secure that the caps were functional in relevant conditions in contact with liquids (water or milk), the caps were surface modified by silylation and esterification to increase the liquid barrier. The results indicate that surface esterification increased the contact angle to 95°. On the other hand, the surface-modified caps could not entirely limit the liquid absorption over longer periods of time (>∼1 h) when the caps were directly exposed to liquid. However, the liquid barrier was satisfactory when the products were exposed to increased relative humidity in refrigerated conditions (relative humidity >76% and temperature <7 °C).

Theoretical foundations of identifying the wood processing industry and prospects for achieving its sustainable development

The goal of this article is to examine and justify the theoretical foundations of identifying the wood processing industry and determine the prospects for achieving its sustainable development in the context of a state of war in Ukraine. The relevance of the topic is driven by the necessity to ensure sustainable use of forest resources, the effective functioning of the industry, and consideration of modern environmental and economic challenges. The study employs a comprehensive research methodology, including the analysis of literary sources and a systemic approach to studying the production and utilization chain of forest resources. Based on the conducted research, key categories such as the wood processing industry, forest management, sawmilling industry, pulp and paper, and furniture industries have been identified. Special emphasis is placed on the interaction between these sectors and ways to optimize the use of forest resources. The article analyzes the component composition of the wood processing industry according to the Classifier of Types of Economic Activity (CPEA-2010) and determines the interconnections between its main branches, such as sawmilling, veneer, particleboard, fiberboard, and furniture industries. It is noted that the wood processing industry is a complex system encompassing both primary and secondary wood processing, paper production, and printing activities. The specificity of production and use of forest resources is determined through the principles of sustainable development. It is proven that the transition to the principles of sustainable development is a priority for the wood processing industry, as it contributes to a balance between economic efficiency, social responsibility, and environmental sustainability. In the context of a state of war, the importance of developing innovative methods of conducting business and production in the wood processing industry is discussed. A comprehensive integrated approach to sustainable development is proposed, wherein various stages of production and use of forest resources interact to achieve common goals: sustainability, efficiency, and a balanced impact on the environment. This approach considers economic, social, and environmental requirements, with a focus on developing the industry in the face of the challenges of a state of war. A systemic view of the production and utilization chain of forest resources allows maximizing the interaction and efficiency of the industry. The practical value of the article lies in the development of recommendations for forming a sustainable development strategy for the wood processing industry in conditions of a state of war. The proposed approaches can serve as a basis for decision-making and implementing state policy in the field of forest use and wood processing, considering modern economic, social, and environmental challenges.

A cellulose nanocrystal-carbon dots@cholestrol fluorescent probe for imaging of plasma membrane with extended time scale

Despite the advancement of plasma membrane imaging techniques, there is an unmet need for fluorescent probes which can “light up” the lipid bilayer with an extended time scale. In this work, a novel fluorescent probe is developed for imaging of plasma membrane. The probe comprises a cellulose nanocrystal (CNC) scaffold derived from low-cost wood pulp, carbon dots (CDs) fluorophore that is in-situ synthesized on the surface of CNC, and cholesterol (Chol) ligand with aminated polyethylene glycol (PEG) spacer. In the CNC-CDs@PEG-Chol configuration, the Chol ligand provides excellent binding affinity onto plasma membrane due to its hydrophobic nature, while CDs contribute to the marvelous optical stability, as well as the high quantum yield of the fluorescent probe. For CNC scaffold, their unique morphological property allows the assembling of dense Chol ligands, and more importantly, impedes the diffusions of imaging moieties into the cytoplasm. Therefore, the fluorescent probe is featured with remarkable specificity and satisfying plasma membrane imaging time window, which covers the co-incubation time from 30 to 90 min. In contrast, the mono-dispersed CDs@PEG-Chol probe can be facilely internalized by the cells at a co-incubation time as short as 20 min. CNC is proven to be responsible for the different imaging time scales by providing the confinement effects. The proposed fluorescent probe is believed to be a promising tool for studying the plasma membrane behaviors associated with cellular physiological processes.

Direct utilization of cationic cellulose nanoparticles derived from maize-stalk parenchyma for intensifying mechanical properties and antibacterial activity in non-refined pulp paper

In recent years, an increasing focus has been placed on the mitigation of carbon dioxide emissions, underscoring the significance of the sustainable energy-conservation industry as a prominent and consequential field of development. As an energy-intensive procedure within the papermaking sector, the process of pulp-fiber beating necessitates an imperative exploration of alternative approaches aimed at mitigating energy consumption. This study has synthesized renewable cationic cellulose nanoparticles (CCNPs) extracted from the parenchymal cells of maize stalk pith. The objective is to demonstrate their viability as a reinforcing additive for paper sheets, thereby reducing the reliance on conventional beating processes. The results showed that CCNPs were prone to augment the physical strength of bleached papers, compared with unbleached papers. The inclusion of 9% CCNPs led to a remarkable 163.5% and 140.0% increase in tear and tensile indexes for bleached Eucalyptus paper, respectively. Incorporating CCNPs into non-refined paper yields physical traits akin to wood pulp paper beaten over 40 °SR. The CCNP-strengthened handsheets exhibited superior tensile and tear index in comparison to commercial dry strength additives such as cationic starch (CS) and cationic polyacrylamide (CPAM). Additionally, at 80 μg/ml concentration, E-B-9 displayed significant bactericidal effectiveness, achieving an impressive 97% reduction in Escherichia coli. This notable outcome is attributed to the presence of quaternary ammonium salt moieties in the formulation. This investigation introduces a promising approach where in the utilization of CCNP as an innovative multifunctional agent for paper holds the potential to enhance paper performance and concurrently reduce production costs.

TDA/rGO@WS with Joule heat and photothermal synergistic effect: A promising adsorption material for all–weather recovery of viscous oil spills at sea

Oil spills are a global environmental protection challenge, and traditional adsorption materials have poor effect on low temperature and high viscosity marine oil spills. This article reports composite adsorption materials TDA/rGO@WS for viscous oil spills: loaded with rGO/TDA coating on a commercial biomass wood pulp sponge (WS), achieving Joule heating, photothermal effect and hydrophobic modification. The results showed that the TDA/rGO@WS has good photothermal conversion ability and Joule heating ability, and the temperature increased to 83.7 °C and 148 °C, respectively, under simulated solar irradiation and additional voltage at room temperature. The efficiency of adsorption at a low temperature of 5 °C increased by 22.41% at 1 sun and by 51.53% at 10 V. Temperature effectively reduced the viscosity of the offshore oil spill and ensures the efficient adsorption of oil spills at low temperatures promoted. The TDA/rGO@WS also showed good hydrophobicity (WCA=129°), excellent efficiency of water–oil separation (99.53%) and good adsorption capacity (9.4–13.68 g/g) for marine fuel oils. TDA/rGO@WS effectively solves the problem of cleaning up high–viscosity oil spills from ships in winter and polar waters, and proposes a new strategy for all–weather efficient treatment of oil spills at sea.

Influence of cellulose nanocrystal surface chemistry and dispersion quality on latex nanocomposite stability, film formation and adhesive properties

The different surface functional groups on carboxylated and sulfated cellulose nanocrystals (CNCs) affect the latex CNC–polymer interactions.

Technological scheme of wood resources utilization model development

In the present work the justification of the urgency of solving the issue of environmental friendliness of materials produced from wood resources is given. The analysis of the production technology of semifinished wood-fiber products is carried out at the current stage of development of the board industry. The estimation of board formation properties of the wood fiber mass produced in disk blade grinding machines is given, and the inefficiency of the used equipment is substantiated. The expediency of using the equipment with cavitation effect as the second grinding stage in the production of wood pulp was substantiated. As a result, the purpose of the present work was the development of the technology for the production of the semifinished wood fiber product with the use of a rotor-pulsation apparatus as the second stage of the wood pulp mill. To achieve the goal, an analysis of modern technologies used in the production of fiberboard was carried out. The model of technological scheme of production of wood fiberboards by wet method in the environment of AnyLogic program package was developed. Based on the technological scheme developed, a dynamic model of the fiberboard production process was built using a rotor-pulsation apparatus in the second stage of wood pulp milling. In the course of research, statistical analysis methods and simulation modelling of technological processes were applied. The results obtained can find application in the production of fiberboard, as well as in the improvement of technological processes at the enterprises of the forest complex.

Click chemistry modifications for the selective crosslinking of wood pulp fibers - effect on the physical and mechanical properties of paper.

The Cu(i)-catalyzed Huisgen cycloaddition click chemistry reaction is of particular interest in the production of paper sheets or natural fiber composites since it leads to the formation of chemically stable bonds between two fibers. This study focuses on the click chemistry modification of kraft pulp fibers. We based our approach on prior research that treated kraft fibers using click chemistry, including propargylation and tosylation reactions. Our focus was on enhancing these treatments to achieve better final sheet properties. After the azidation of tosylated fibers, the crosslinking is carried out with and without a catalyst using water as a solvent to form enhanced kraft fiber sheets. The chemical characterization and the mechanical properties of fibers obtained at intermediate stages confirmed the presence of various functions on the surface of the modified fibers, with a very high degree of substitution and the inter-fiber cross-linking by click chemistry. The presence of inter-fibers covalent bonds led to significant improvements in the mechanical strength and tensile stiffness of the sheets.

Creation of Polycaprolactone–wood Pulp Composites and the Evaluation of Degradability in Soil

Creation of Polycaprolactone–wood Pulp Composites and the Evaluation of Degradability in Soil

Addition of green and black liquor in kraft pulping of Eucalyptus dunnii wood: possible solutions for the problems with kraft pulping caused by high calcium content

In our previous study, we demonstrated that Eucalyptus dunnii samples containing high calcium content show inferior pulping properties concerning delignification and polysaccharide degradation. This led us to investigate alternative methods for improving the pulping process of these samples. In the present work, we evaluated the effects of incorporating black and green liquors into the Eucalyptus dunnii chips before kraft pulping, aiming to enhance the pulping process and overcome the negative impact of high calcium content. The addition of both black and green liquors resulted in specific enhancements, with the green liquor having a more significant impact on the pulping process. Even wood samples with the highest calcium content demonstrated satisfactory pulping results when treated with green liquor. Delignification occurred more rapidly, and selectivity was higher for samples pre-treated with green liquor before kraft pulping. Moreover, calcium tended to follow the fiber under these conditions rather than being released into the black liquor, which may contribute to the improved pulping performance. Subsequent bleaching tests revealed that the bleachability of green liquor-treated pulp was nearly identical to that of a control pulp, while maintaining a higher viscosity. This suggests that incorporating green liquor into the pre-treatment process not only improves the pulping performance of Eucalyptus dunnii samples with high calcium content but also maintains desirable bleachability characteristics. To better understand the underlying mechanisms of these findings, we discuss the potential chemical explanations behind the observed improvements.

Transpiration rates from mature Eucalyptus grandis × E. nitens clonal hybrid and Pinus elliottii plantations near the Two Streams Research Catchment, South Africa

Abstract. Pine plantations are the dominant species currently planted within the South African commercial forestry industry. Improvements in bio-economy markets for dissolving wood pulp products have seen an expansion in fast-growing Eucalyptus plantations due to their higher productivity rates and better pulping properties than pine. This has raised concerns regarding the expansion of Eucalyptus plantations and how they will affect water resources as they have been reported to have higher water use (quantified using transpiration rates) than pine. We measured transpiration rates (mm yr−1), diameter at breast height (quantified as quadratic mean diameter, Dq, m) and leaf area index of an 8-year-old Eucalyptus grandis × Eucalyptus nitens clonal hybrid (GN) and a 20-year-old Pinus elliottii. Transpiration rates were measured for two consecutive hydrological years (2019/20 and 2020/21) using a heat ratio sap-flow method, calibrated against a lysimeter. In the 2019/20 year, annual transpiration for P. elliottii exceeded GN by 28 %, while for the 2020/21 hydrological year, there was no significant difference between the transpiration of the two species, despite a 17 % and 21 % greater leaf area index for P. elliottii than GN in 2019/20 and 2020/21 measurement years respectively. Quadratic mean diameter increments were statistically similar (p &gt; 0.05) in 2019/20, whereas the 2020/21 year produced significant differences (p&lt;0.05). Tree transpiration is known to be influenced by climatic variables; therefore, a random forest regression model was used to test the level of influence between tree transpiration and climatic parameters. The soil water content, solar radiation and vapour pressure deficit were found to highly influence transpiration, suggesting these variables can be used in future water-use modelling studies. The profile water content recharge was influenced by rainfall events. After rainfall and soil profile water recharge, there was a rapid depletion of soil water by the GN trees, while the soil profile was depleted more gradually at the P. elliottii site. As a result, trees at the GN site appeared to be water stressed (reduced stem diameters and transpiration), suggesting that there was limited access to alternative water source (such as groundwater). The study concluded that previous long-term paired catchment studies indicate that eucalypts use more water than pine; however, periods of soil water stress and reduced transpiration observed in this study must be accommodated in hydrological models. Long-term total soil water balance studies are recommended in the same region to understand the long-term impact of commercial plantations on water resources.

INFLUENCE OF ASPECT RATIO OF TEMPO-OXIDIZED CELLULOSE NANOFIBERS (TOCNs) FROM WOOD PULP ON POLYMERIC MEMBRANE PROPERTIES

The incorporation of TEMPO-oxidized cellulose nanofibers (TOCNs) derived from wood pulp resulted in an improvement in the characteristics of polymeric membranes made up of poly (methyl vinyl ether maleic acid)/PMVEMA and poly (ethylene glycol)/PEG. The membranes were constructed, and TOCNs were included in the formulation at a rate of 5 wt%. TOCNs were categorized as either short or long, depending on the aspect ratio measurement. According to the findings of the research, the various lengths of TOCNs resulted in variances in the optical transmittance properties, contact angles, and whiteness level of the membranes, in addition to a little variation in the tensile and thermal properties of the material. When compared to short TOCNs, long TOCNs offer somewhat improved performance in terms of optical transmittance, whiteness level, tensile characteristics, and thermal stability. The results of this study reveal the significance of the morphology of nanocellulose in determining the properties of the composite that includes it. Thus, the characteristics of the target membrane were greatly influenced by nanocellulose morphology.

Pembuatan Pulp and Paper Berbahan Dasar Serat Kulit Pinang (Areca Catechu L.) dengan Penambahan Kitosan Sebagai Zat Aditif Antibakteri

The need for paper in Indonesia continues to increase along with population growth and progress in activities related to paper use. However, the supply of materials used to make wood pulp will also decrease over time. Continuous exploitation of forests will cause environmental problems. An alternative to reduce the impact on the environment is to replace the raw material for making non-wood paper which is rich in cellulose fiber. One non-wood raw material that is rich in fiber is areca nut shell. However, the current problem is that paper can be contaminated with microorganisms from free (dirty) air, dirty hands of people who handle it or from unsterile storage places. So, we need a new alternative to prevent this problem, namely by adding antibacterial additives to the paper. The method used is the process of delignification, filtration, drying, bleaching and adding chitosan additives. The conclusions obtained that the optimum concentration of the NaOH cooking solution was found at a NaOH concentration of 10%, the optimum time was obtained at a delignification time of 6 hours, and the best concentration of chitosan additive was 6% with an inhibition zone of 7.01 mm. The inhibition zone obtained is in the weak category.

Chemical and rheological analysis of unaged and aged bio-extended binders containing lignin

The use of alternative renewable sources to totally or partially replace bitumen is one of the most current challenges in the road pavement sector. The growing energy cost and environmental concerns lead to the necessity to find alternative solutions, by supporting at the same time sustainability and circular economy principles. Within this framework, this paper presents the application of a powder lignin, a natural bio-polymer deriving from by-products of wood pulp and paper industry, to replace part of bitumen. The bituminous blend consisting in 70% of bitumen and 30% of powder lignin (by weight) was made in laboratory through the use of a high shear stirring mixer, and a reference plain bitumen characterized by a similar consistency (i.e., same penetration grade) was used as comparison. Then, an extensive investigation on chemical and rheological properties of the bio-binder is presented. Fourier transform infrared spectroscopy (FTIR), saturates, aromatics, resins and asphaltenes (SARA), bending beam rheometer (BBR), frequency sweep tests and multiple stress creep recovery tests (MSCR) with a dynamic shear rheometer (DSR) were performed. Moreover, unaged, short- and long-term aging conditions were considered. Results indicated that powder lignin dominates the rheological behavior of the bio-binder and, from chemical analysis, it seems that it partially acts as a filler and partially as a binder. This would result in improved performances at both low and high temperatures, leading to a wider temperature range of performance grade (PG). Moreover, despite a stiffening effect is recognized, lignin also offers an antioxidant potentiality, reducing the aging susceptibility of the investigated bio-binder.

Prolonging broccoli shelf life through controlled release of plai essential oil using palm wood sachet as a novel absorbent material with reusable properties.

Palm wood powder derived from palm wood waste was utilized as a novel absorbent material. The investigation involved exploring its pore structure and size to achieve the controlled release of bioactive compounds from plai oil, providing protection against pathogenic bacteria and thereby extending the shelf life of broccoli. The palm wood sachet was prepared before being placed into the broccoli bag. The process to create the sachet involved freezing the palm wood at -10°C and then drying it at a temperature of 200°C. After drying, the material was ground to achieve a particle size of 20 mesh and then packaged into sachets made from wood pulp. The optimized palm wood plai oil sachet (PWPS), measuring 5×7cm, with a thickness of 0.58µm, was produced by soaking 2g of palm powder in plai oil at a concentration of 30µL/mL before drying and packing it inside a 5-L polyethylene plastic bag (24×34cm) along with broccoli (150g). The packages were kept at 4°C for 20days to determine the antimicrobial activity of the PWPS and broccoli quality. PWPS significantly inhibited the growth of Escherichia coli, Salmonella Typhimurium, Staphylococcus aureus, and Listeria monocytogenes in broccoli for at least 20days. The sachet demonstrated complete inhibition of all bacteria when reused at least two times and an 80% reduction in efficacy after three uses. Moreover, the PWPS controlled the growth of total aerobic bacteria and yeast and mold in broccoli, meeting microbiological criteria for up to 14days. Broccoli stored with PWPS showed good quality results and contained high antioxidant value. These results demonstrate the potential application of PWPS in controlling food pathogens and spoilage microbes during storage. PRACTICAL APPLICATION: This study introduces a novel absorbent material made from palm wood powder, addressing the need for utilizing abundant waste palm wood in the food industry. The material benefits the safe transportation of vegetables from farms to markets. Its porous structure allows efficient absorption of plai oil emulsion, ensuring pathogen-free and high-quality treated broccoli. The reusable sachets benefit farmers seeking to extend the shelf life of fresh produce. This cost-effective method utilizes plai oil vapor, making it suitable for large-scale production.

Characterization of spray dried cellulose nanofibrils produced by a disk refining process at different fineness levels

Three types of wood pulp feedstocks including bleached softwood kraft, unbleached softwood kraft and old corrugated containers were disk refined to produce cellulose nanofibrils at different fineness levels ranging from 50 to 100%, and the resulting aqueous suspensions of cellulose nanofibrils were spray dried. The spray drying experiments were carried out to examine different processing conditions for the different CNF feedstock types and fines level at various suspension concentrations to produce dry samples with free-flowing powder morphologies. The fineness levels and solids contents of CNF suspensions were set to 80% or more and 1.8% or less, respectively. If the solids content of the CNF solutions was high and the fibrillation level was low, plugging was experienced in the spray head because of the high viscosity of the suspensions, resulting in production of poor-quality powders. In terms of reduction in processing energy, even if the CNF suspension solids content was increased to 1.5 wt.%, the powder quality and the production yields were excellent. It was confirmed that high-quality powder under 20 µm were produced at a 90% fibrillation level of all CNF feedstocks. The resulting dry CNF powders were characterized to determine particle size distributions and morphological properties via a scanning electron microscope and a laser diffraction particle size analyzer. The particle sizes were smaller at higher fibrillation levels and lower solids content of the CNF suspensions. The CNF suspension derived from bleached kraft pulp, the average particle size decreased by 43% and 33% with the lowered solids contents from 1.8 to 1%, and the increased fineness levels from 80 to 100%, respectively.