Pulp Fibers Research Articles

A comparative study of kraft pulp fibres and the corresponding fibrillated materials as reinforcement of LDPE- and HDPE-biocomposites

A comparative study of kraft pulp fibres and the corresponding fibrillated materials as reinforcement of LDPE- and HDPE-biocomposites

Human Dental Pulp Stem Cells Are Subjected to Metabolic Reprogramming and Repressed Proliferation and Migration by the Sympathetic Nervous System via α1B-Adrenergic Receptor

IntroductionHuman dental pulp stem cells (hDPSCs) reside in specialized microenvironments in the dental pulp, termed “niches,” which are composed of diverse cellular components including nerves. Sensory nerves can positively regulate the expansion and differentiation of pulp cells, while the biological effects of the sympathetic nervous system (SNS) on hDPSCs remain elusive. This study is devoted to investigating the effects and underlying mechanisms of the SNS on the proliferation and migration of hDPSCs. MethodsThe distribution of sympathetic nerve fibers in human dental pulp was examined by immunofluorescence staining of tyrosine hydroxylase. The concentration of norepinephrine in healthy and carious human dental pulp tissues was detected using enzyme-linked immunosorbent assay. RNA-sequencing was applied to identify the dominant sympathetic neurotransmitter receptor in hDPSCs. Seahorse metabolic assay, adenosine triphosphate assay, lactate assay, and mitochondrial DNA copy number were performed to determine the level of glycometabolism. Transwell assay, wound healing assay, 5-ethynyl-2'-deoxyuridine staining assay, cell cycle assay, and Cell Counting Kit-8 assay were conducted to analyze the migratory and proliferative capacities of hDPSCs. ResultsSprouting of sympathetic nerve fibers and an increased concentration of norepinephrine were observed in inflammatory pulp tissues. Sympathetic nerve fibers were mainly distributed along blood vessels, and aldehyde dehydrogenase 1–positive hDPSCs resided in close proximity to neurovascular bundles. ADRA1B was identified as the major sympathetic neurotransmitter receptor expressed in hDPSCs, and its expression was enhanced in inflammatory pulp tissues. In addition, the SNS inhibited the proliferation and migration of hDPSCs through metabolic reprogramming via ADRA1B and its crosstalk with serine-threonine kinase and p38 mitogen-activated protein kinase signaling pathways. ConclusionsThis study demonstrates that the SNS can shift the metabolism of hDPSCs from oxidative phosphorylation to anaerobic glycolysis via ADRA1B and its crosstalk with serine-threonine kinase and p38 mitogen-activated protein kinase signaling pathways, thereby inhibiting the proliferative and migratory abilities of hDPSCs. This metabolic shift may facilitate the maintenance of the quiescent state of hDPSCs.

Bamboo fiber-derived porous carbon microspheres decorated with MnO2 for enhanced supercapacitor performance

Manganese dioxide holds great potential as a pseudocapacitive material for supercapacitors. However, its limited electrical conductivity hampers the realization of its theoretically predicted capacitance. In this study, we successfully synthesized MnO2 in-situ on porous carbon microspheres derived from bamboo pulp fibers using a hydrothermal method. The morphology and phase of MnO2 were controlled by adjusting reduction reaction of KMnO4. Porous carbon spheres coated with sheet-like δ-MnO2 were obtained at a low Mn/C ratio, resulting in an impressive specific surface area of 401.4 m2 g−1. The composite exhibited remarkable specific capacitance of 364.4 F g−1 at a current density of 0.5 A g−1 and exhibited excellent capacitance retention of 99.7 % after undergoing 10,000 cycles. Incorporation of MnO2 improved the capacitance performance of porous carbon spheres by 81 %. This study presents promising prospects for the sustainable and environmentally friendly production of bamboo-derived carbon composite materials for supercapacitors.

Paper-Based Hydroelectric Generators for Water Evaporation-Induced Electricity Generation.

The research presented in this paper introduces a novel environmental energy-harvesting technology that harnesses electricity from the evaporation of water using porous structural materials. Specifically, a strategy employing paper-based hydroelectric generators (p-HEGs) is proposed to capture the energy produced during water evaporation and convert it into usable electricity. The p-HEGs offer several advantages, including simplicity in fabrication, low cost, and reusability. To evaluate their effectiveness, the water evaporation-induced electrical output performance of four different p-HEGs are compared. Among the variants tested, the p-HEG combining wood pulp and polyester fiber exhibits the best output performance. At room temperature, this particular p-HEG generates a short-circuit current and open-circuit voltage of ≈0.4µA and 0.3V, respectively, thereby demonstrating excellent electrical stability. Furthermore, the electrical current and voltage generated by the p-HEG through water evaporation are able to power an LED light, both individually and in series and parallel connections. This study delves into the potential of electricity harvesting from water evaporation and establishes it as a viable method for renewable energy applications.

Cool roofing tiles derived from recycled corrugated containers

To reduce the heat island effect brought by conventional asphalt roofing products with high solar absorption, we propose a category of self-cleaning and self-cooling composited roofing tile (CRT) made of old corrugated containers (OCC) and tung oil inspired by traditional Chinese oil-paper umbrellas, which can be fabricated at scale and easily recycled for roofing applications. Compared with asphalt shingles, CRTs can improve the solar reflection due to the randomized structure of the cellulose microfibers, contributing to a significant temperature difference of ∼13.2 °C. In addition, they have a high thermal emissivity of 0.93 in the atmospheric window, radiating great amounts of heat into the cold outer space (∼ 3 K). The top layer tung oil film smeared on the OCC pulp fibers transforms the roofing tile from a waterabsorbing to a waterproofing state and significantly enhances the mechanical strength, contributing to a stable thermal performance in outdoor applications. Furthermore, dyed CRTs can selectively reflect visible light for desired colors and effectively reflect near-infrared light to reduce solar heating, which synchronously achieves roof cooling and aesthetic variety. These cheap, eco-friendly, and multifunctional roofing tiles can provide a value-added path for OCC recycling, which may inspire more radiative cooling composites purely from recycling waste towards an energy-saving and sustainable society.

Thermoplastic Starch Biocomposite Films Reinforced with Nanocellulose from Agave tequilana Weber var. Azul Bagasse.

In this work, cellulose nanocrystals (CNCs), bleached cellulose nanofibers (bCNFs), and unbleached cellulose nanofibers (ubCNFs) isolated by acid hydrolysis from Agave tequilana Weber var. Azul bagasse, an agro-waste from the tequila industry, were used as reinforcements in a thermoplastic starch matrix to obtain environmentally friendly materials that can substitute contaminant polymers. A robust characterization of starting materials and biocomposites was carried out. Biocomposite mechanical, thermal, and antibacterial properties were evaluated, as well as color, crystallinity, morphology, rugosity, lateral texture, electrical conductivity, chemical identity, solubility, and water vapor permeability. Pulp fibers and nanocelluloses were analyzed via SEM, TEM, and AFM. The water vapor permeability (WVP) decreased by up to 20.69% with the presence of CNCs. The solubility decreases with the presence of CNFs and CNCs. The addition of CNCs and CNFs increased the tensile strength and Young's modulus and decreased the elongation at break. Biocomposites prepared with ubCNF showed the best tensile mechanical properties due to a better adhesion with the matrix. Images of bCNF-based biocomposites demonstrated that bCNFs are good reinforcing agents as the fibers were dispersed within the starch film and embedded within the matrix. Roughness increased with CNF content and decreased with CNC content. Films with CNCs did not show bacterial growth for Staphylococcus aureus and Escherichia coli. This study offers a new theoretical basis since it demonstrates that different proportions of bleached or unbleached nanofibers and nanocrystals can improve the properties of starch films.

The Effect of Cellulose Nanofibres on Dewatering during Wet-Forming and the Mechanical Properties of Thermoformed Specimens Made of Thermomechanical and Kraft Pulps.

Due to environmental concerns regarding single-use plastic materials, major efforts are being made to develop new material concepts based on biodegradable and renewable resources, e.g., wood pulp. In this study, we assessed two types of wood pulp fibres, i.e., thermomechanical pulp (TMP) and Kraft pulp fibres, and tested the performance of the fibres in wet-moulding and thermopressing trials. Kraft pulp fibres appeared to retain more water than TMP, increasing the dewatering time during wet-moulding and apparently increasing the compression resistance of the pulp during thermoforming. Additionally, cellulose nanofibres (CNF) were added to the pulps, which improved the mechanical properties of the final thermopressed specimens. However, the addition of CNF to the pulps (from 2 to 6%) had a further decrease in the dewatering efficiency in the wet-moulding process, and this effect was more pronounced in the Kraft pulp specimens. The mechanical performance of the thermoformed specimens was in the same range as the plastic materials that are conventionally used in food packaging, i.e., modulus 0.6-1.2 GPa, strength 49 MPa and elongation 6-9%. Finally, this study demonstrates the potential of wood pulps to form three-dimensional thermoformed products.

Role of intrinsic and extrinsic xylan in softwood kraft pulp fiber networks

Xylan is primarily found in the secondary cell wall of plants providing strength and integrity. To take advantage of the reinforcing effect of xylan in papermaking, it is crucial to understand its role in pulp fibers, as it undergoes substantial changes during pulping. However, the contributions of xylan that is added afterwards (extrinsic) and xylan present after pulping (intrinsic) remain largely unexplored. Here, we partially degraded xylan from refined bleached softwood kraft pulp (BSKP) and adsorbed xylan onto BSKP. Enzymatic degradation of 1 % xylan resulted in an open hand sheet structure, while adsorption of 3 % xylan created a denser fiber network. The mechanical properties improved with adsorbed xylan, but decreased more significantly after enzymatic treatment. We propose that the enhancement in mechanical properties by adsorbed extrinsic xylan is due to increased fiber-fiber bonds and sheet density, while the deterioration in mechanical properties of the enzyme treated pulp is caused by the opposite effect. These findings suggest that xylan is decisive for fiber network strength. However, intrinsic xylan is more critical, and the same properties cannot be achieved by readsorbing xylan onto the fibers. Therefore, pulping parameters should be selected to preserve intrinsic xylan within the fibers to maintain paper strength.

A facile route for concurrent fabrication and surface selective functionalization of cellulose nanofibers by lactic acid mediated catalysis

Celulose nanofibers are lightweight, recycable, biodegradable, and renewable. Hence, there is a great interest of using them instead of fossil-based components in new materials and biocomposites. In this study, we disclose an environmentally benign (green) one-step reaction approach to fabricate lactic acid ester functionalized cellulose nanofibrils from wood-derived pulp fibers in high yields. This was accomplished by converting wood-derived pulp fibers to nanofibrillated “cellulose lactate” under mild conditions using lactic acid as both the reaction media and catalyst. Thus, in parallel to the cellulose nanofibril production, concurrent lactic acid-catalyzed esterification of lactic acid to the cellulose nanofibers surface occured. The direct lactic acid esterification, which is a surface selective functionalization and reversible (de-attaching the ester groups by cleavage of the ester bonds), of the cellulose nanofibrils was confirmed by low numbers of degree of substitution, and FT-IR analyses. Thus, autocatalytic esterification and cellulose hydrolysis occurred without the need of metal based or a harsh mineral acid catalysts, which has disadvantages such as acid corrosiveness and high recovery cost of acid. Moreover, adding a mineral acid as a co-catalyst significantly decreased the yield of the nanocellulose. The lactic acid media is successfully recycled in multiple reaction cycles producing the corresponding nanocellulose fibers in high yields. The disclosed green cellulose nanofibril production route is industrial relevant and gives direct access to nanocellulose for use in variety of applications such as sustainable filaments, composites, packaging and strengthening of recycled fibers.

Pretreated cellulose fiber for enhancing fire resistance of flexible polyurethane foam composites with reinforced properties

To promote environmentally sustainable behavior, it is meaningful to develop a simple preparation method of polyurethane foam (PUF) with excellent performance and degradability. Herein, PUF composites were economically and conveniently synthesized by mixed foaming of polyurethane prepolymer and cellulose nanocrystals (CNCs). After the hydrolysis of dissolving pulp fibers with formic acid (FA), hydrophobic ester groups were introduced in CNCs, thereby increasing the surface hydrophobicity of PUF composites. CNCs acted as a reinforcement agent capable can replace 10% up to 60% prepolymer for foaming, the modified PUF exhibiting gradient morphology structure and enhanced specific mechanical and thermal properties. When the CNCs replacement ratio was 50%, the maximum compressive stress was 1103.19 kPa, which is 21-fold that of the original foam. Remarkably, the addition of CNCs enhanced thermal insulation performance of the prepared foam, which of thermal conductivity decreased from 0.0780 W/mK to 0.0549 W/mK. The upgraded polyurethane foam composites promise to open exciting new windows on producing fire resistance PUF with enhanced performance.

Bergamot Polyphenolic Extract Combined with Albedo and Pulp Fibres Counteracts Changes in Gut Microbiota Associated with High-Fat Diet: Implications for Lipoprotein Size Re-Arrangement.

Evidence exists that the gut microbiota contributes to the alterations of lipid metabolism associated with high-fat diet (HFD). Moreover, the gut microbiota has been found to modulate the metabolism and absorption of dietary lipids, thereby affecting the formation of lipoproteins occurring at the intestinal level as well as systemically, though the pathophysiological implication of altered microbiota composition in HFD and its role in the development of atherosclerotic vascular disease (ATVD) remain to be better clarified. Recently, evidence has been collected indicating that supplementation with natural polyphenols and fibres accounts for an improvement of HFD-associated intestinal dysbiosis, thereby leading to improved lipidaemic profile. This study aimed to investigate the protective effect of a bergamot polyphenolic extract (BPE) containing 48% polyphenols enriched with albedo and pulp-derived micronized fibres (BMF) in the gut microbiota of HFD-induced dyslipidaemia. In particular, rats that received an HFD over a period of four consecutive weeks showed a significant increase in plasma cholesterol, triglycerides and plasma glucose compared to a normal-fat diet (NFD) group. This effect was accompanied by body weight increase and alteration of lipoprotein size and concentration, followed by high levels of MDA, a biomarker of lipid peroxidation. Treatment with a combination of BPE plus BMF (50/50%) resulted in a significant reduction in alterations of the metabolic parameters found in HFD-fed rats, an effect associated with increased size of lipoproteins. Furthermore, the effect of BPE plus BMF treatment on metabolic balance and lipoprotein size re-arrangement was associated with reduced gut-derived lipopolysaccharide (LPS) levels, an effect subsequent to improved gut microbiota as expressed by modulation of the Gram-negative bacteria Proteobacteria, as well as Firmicutes and Bacteroidetes. This study suggests that nutraceutical supplementation of HFD-fed rats with BPE and BMP or with their combination product leads to restored gut microbiota, an effect associated with lipoprotein size re-arrangement and better lipidaemic and metabolic profiles.

Integrated asymmetric cellulose aerogel membrane with triple thermal insulation and unidirectional liquid penetration for personal thermal management

With the rapid development of personal thermal management, there is an urgent need for an advanced material that can effectively integrate various thermal functions to keep body warm and cope with the cold outdoor environment. Herein, a multifunctional cellulose based asymmetric modification aerogel membrane (ACAM) encompassing thermal insulation, thermal radiation reflection, solar adsorption, and directional perspiration has been fabricated via bottom-up assembling biomass sisal fibers and pulp fibers into cellulose aerogel membrane, followed by spin-coating ionic liquid modified graphene (IGNs) and silver nanowires (AgNWs) on both sides of the cellulose aerogel membrane, respectively. The results showed that the temperature on the IGNs side is 14.2 °C higher than that of the cotton cloth after 30 s of sunlight exposure. Compared with pure cellulose aerogel membrane, the AgNWs side of ACAM has lower infrared emissivity and higher infrared reflectivity, and the temperature is reduced by 3.2 °C in indoor environment. In addition, the ACAM has asymmetric wettability, which facilitates the transfer of sweat from the hydrophobic side to the hydrophilic side and perspiration penetration was achieved in 10.6 s to obtain the comfort of wearing. The ACAM also exhibits excellent breathability, easy preparation and controllable functional structures. This work may provide a new idea for heat management and dynamic moisture to ensure maximum comfort in very harsh environments.

Microwave-assisted formic acid/cold caustic extraction for separation of cellulose and hemicellulose from biomass

Effective separation of cellulose and hemicellulose from lignocellulosic biomass is an essential step for creating high-value products. In this study, a modified treatment process was proposed for cellulose purification via microwave-assisted formic acid catalytic hydrolysis followed by cold caustic extraction. The sugar content in the extract was determined using UV spectrophotometer and dual-wavelength visible spectrophotometry. Combined microwave-assisted formic acid (M-FA) with cold caustic extraction (CCE) treatments achieved rapid separation and removal of hemicelluloses from waste hardwood pulp fibers. The hemicelluloses content decreased from 28.6% to 2.3%, and the lignin content changed from 27.8% to 6.1%, which resulted in a maximal cellulose content of 91.5% under the optimal M-FA/CCE treatment conditions. In addition, the crystallinity index of pulp fibers increased from 54.3% to 67.1%, and the initial decomposition temperature decreased from 335.4 to 270.2 °C with the decrease of hemicellulose and lignin content. The modified process provided a sustainable and effective method for hemicellulose separation and lignin removal from cellulosic fibers.

High-Consistency Mechano-Enzymatic Fibrillation of Bamboo Pulp Fibers to Produce Precursors for Highly Fibrillated Cellulose and Dense Films with Multifunctionalities

High-Consistency Mechano-Enzymatic Fibrillation of Bamboo Pulp Fibers to Produce Precursors for Highly Fibrillated Cellulose and Dense Films with Multifunctionalities

Impact of high consistency enzymatic hydrolysis and defibration drying on cellulose fiber pore characteristics

AbstractThe purpose of this study is to examine the hornification of enzymatically hydrolyzed high consistency softwood kraft pulp in an experimental defibration dryer. This device dries pulp under turbulent conditions which can prevent interfiber bonding and produce a separated fiber population. This is useful in certain applications, such as composites, which require dry, unbonded pulp fibers. In this study, we examine how fibrillated pulps behave in the dryer with respect to pore expansion in hydrolysis and collapse in drying (hornification). It was found that the endoglucanase cocktail increased the micro-, meso-, and macropore volumes as a function of hydrolysis time. Drying decreased the pore volumes of each size category, with the biggest changes in the macropore region. The pulp with the highest swelling after hydrolysis had the lowest swelling after drying. The mesopores that were formed in hydrolysis were somewhat preserved after drying. After drying, unfibrillated pulp had good fiber separation, while the highly fibrillated samples formed sub-millimeter, spherical particles.

Surface characterization of pulp fiber from mixed waste newspaper and magazine deinked-pulp with combined cellulase and laccase-violuric acid system (LVS)

The current study assesses the use of combined cellulase and laccase-violuric acid system (LVS) for deinking secondary fibers containing mixed 70% old newsprint (ONP) and 30% old magazine (OMG). Optical and strength properties, surface chemical composition, fiber crystallinity, fiber morphology changes during the deinking process, and pulp water retention value (WRV) were assessed by electron spectroscopy for chemical analysis (ESCA), Fourier transform infrared spectrometry (FTIR), field emission scanning electron microscopy (FESEM), and the centrifuge method. Results revealed the synergistic delignification and deinking effects of cellulase and LVS making enzymatic treatment a promising alternative for chemical deinking. Pulp deinked with cellulase-LVS indicated a lower ERIC (effective residual ink concentration), better optical and strength properties, fiber surface with higher O/C ratio, and lower lignin coverage, higher fiber crystallinity index, and improved pulp WRV. Furthermore, FESEM photographs demonstrated that more fibrils appeared on the fiber surface due to synergistic effects between enzymes.

Multiplex CRISPR editing of wood for sustainable fiber production.

The domestication of forest trees for a more sustainable fiber bioeconomy has long been hindered by the complexity and plasticity of lignin, a biopolymer in wood that is recalcitrant to chemical and enzymatic degradation. Here, we show that multiplex CRISPR editing enables precise woody feedstock design for combinatorial improvement of lignin composition and wood properties. By assessing every possible combination of 69,123 multigenic editing strategies for 21 lignin biosynthesis genes, we deduced seven different genome editing strategies targeting the concurrent alteration of up to six genes and produced 174 edited poplar variants. CRISPR editing increased the wood carbohydrate-to-lignin ratio up to 228% that of wild type, leading to more-efficient fiber pulping. The edited wood alleviates a major fiber-production bottleneck regardless of changes in tree growth rate and could bring unprecedented operational efficiencies, bioeconomic opportunities, and environmental benefits.

On the Roles of Cellulose Nanocrystals in Fiber Cement: Implications for Rheology, Hydration Kinetics, and Mechanical Properties.

Fiber cement reinforced with pulp fibers is one of the key drivers for the decarbonization of nonstructural building materials, where the inclusion of sustainable pulp fibers at high proportions (i.e., > 8 wt %) renders poor workability of fiber-cement slurry with a concomitant loss in mechanical strength. Petrochemical-derived superplasticizers, i.e., polycarboxylates (PCEs), are predominantly used in fiber cement (including cement mortars) because they dramatically improve (content <0.5 wt %) the slurry rheology but reduce the rate of hydration and weaken the strength of the cured composite. Thus, it is crucial to explore renewable and bio-based superplasticizers devoid of any negative traits (if possible) of the conventional PCEs. In this study, we examined wood-derived cellulose nanocrystals (CNCs) as a multifunctional additive in fiber cement (bleached pulp fiber content: 8 wt %). In fiber cement, variation of the content (0.02-4 wt %) of CNCs resulted in improvement in the shear thinning behavior of the fiber-cement slurry and thereafter increased the hydration kinetics at high CNC contents (2-4 wt %). Notably, the flexural strength of the composite also exhibited improvement upon the addition of CNCs; the maximum strength was observed at 4 wt % of CNCs. Overall, the beneficial roles of CNCs afforded >10 wt % (in-total) bio-based content in fiber cement without compromising the mechanical strength and curing time (compared to PCEs); hence, the findings of this study could unravel new avenues in interface engineering of cement composites leveraging the multifunctional features of biomaterials, thus enhancing sustainability.

Analysis of causes for high hydration and low drainage rate of wheat straw chemi-thermo-mechanical pulp

The wheat straw chemi-mechanical pulp has the characteristics of high yield, good mechanical performance and low production cost. However, there are significant problems in the papermaking process by such as high pulp hydration, poor drainage, and large energy consumption during the paper drying-process. It was found that during the chemical mechanical pulping of wheat straw, due to the residual alkali and temperature, the hemicellulose in the pulp was continuously dissolved, some of it entered the water phase, and some of it migrated to the fiber surface. Which reflected in the raise in cation demand for anionic substances in the aqueous phase, the increase in carboxyl content on the surface of pulp fibers, and the aggravation in hydration degree. Further research found that the high valence metal ions can combine the carboxylate radical on the hemicellulose molecule in the aqueous phase with the carboxylate radical on the pulp surface to form a covalent bond, so that the hemicellulose entering the aqueous phase can be re-adsorbed to the fiber surface, thus further increasing the degree of pulp hydration. Carboxymethyl starch was used to simulate hemicellulose, and the hemicellulose re-adsorption phenomenon verification experiments were reproduced in a calcium ion environment. The above findings indicate that during the production of wheat straw chemi-mechanical pulp process, the hemicellulose dissolved and re-adsorption not only leads to the increase of pulp hydration, but also results in poor water filtration during paper formation. Therefore, this study can provide a theoretical basis for optimizing the production process of chemi-mechanical pulp of wheat straw and controlling the technology and method of pulp hydration.

Identification of document paper using hybrid feature extraction.

Document forgery is a significant issue in Korea, with around ten thousand cases reported every year. Analyzing paper plays a crucial role in examining questionable documents such as marketable securities and contracts, which can aid in solving criminal cases of document forgery. Paper analysis can also provide essential insights in other types of criminal cases, serving as an important clue for solving cases such as the source of a blackmail letter. The papermaking process generates distinct forming fabric marks and formations, which are critical features for paper classification. These characteristics are observable under transmitted light and are created by the forming fabric pattern and the distribution of pulp fibers, respectively. In this study, we propose a novel approach for paper identification based on hybrid features. This method combines texture features extracted from images converted using the gray-level co-occurrence matrix (GLCM) approach and a convolutional neural network (CNN), with another set of features extracted by the CNN using the same images as input. We applied the proposed method to classification tasks for seven major paper brands available in the Korean market, achieving an accuracy of 97.66%. The results confirm the applicability of this method for visually inspecting paper products and demonstrate its potential for assisting in solving criminal cases involving document forgery.