Volume 40, Issue 2

In this paper, X 1 and X 2 (two different xylanases), were employed to pretreat oxygen-delignified kraft softwood pulp. X 2 could handle unwashed pulp, while X 1 needed washed pulp. Subsequently, the effects of two xylanases on the physical properties, microstructure and fiber characteristics of pulp were investigated. Compared to the ECF bleached pulp (OD 0 E p D 1 ), the brightness (86.9 %ISO), tensile index (28.4 N·m/g) and burst index (1.67 kPa·m 2 /g) of the ECF bleached pulp treated with X 2 xylanase (9 U/g) increased by 2.4 %ISO, 4.8 % and 24.6 %. After X 2 xylanase pretreatment, the fiber length of pulp decreased slightly, the content of fine fibers increased, and the water retention value increased. Due to the pretreatment of X 2 xylanase, some non-fibrous components and chromophores in the pulp were removed, and the intrinsic viscosity and average molecular weight of the pulp were reduced. The crystallinity of cellulose decreases by 1 %, the fiber surface becomes rough, and voids are created, the specific surface area increases, and the average pore size increases. These findings suggest that enzyme pretreatment is a green and highly effective approach that not only significantly enhances pulping performance but also demonstrates excellent adaptability to complex processing environments and it streamlines the traditional pulping process effectively.

In this study, a two-stage, low-consistency (LC) refining process at the Holmen Braviken paper mill in Sweden was examined to evaluate the relationship between energy input, fibre distributions, and pulp properties, including handsheet properties. The LC refiners used thermo-mechanical pulp based on 100 % Norway spruce, with two specific energy levels: “low” (≈80 kWh/adt) or “high” (≈100 kWh/adt). All four permutations of these settings were examined. Overall, higher refining efficiency (measured by the increase in tensile index per applied energy) was observed in the first LC refiner stage than in the second. To further explore the impact of LC refining, pulp particle distributions were investigated. Samples from before, between and after the two LC stages were analysed using an optical fibre analyser, which provided detailed data on length-width-curl-fibrillation distributions. The impact of LC refining on these distributions was quantified using Kolmogorov-Smirnov statistics, highlighting statistically significant changes observed in the length and curl distributions. We investigated the correlation between energy input into the LC refiners and the impact on fibre distributions and handsheet properties. These insights underscore the effectiveness of our analytical approach and its potential for refining process control in mechanical pulping, offering a method for more targeted and efficient adjustments.

This study investigates the formation of finger ridges during the paper manufacturing process, highlighting the role of structural inhomogeneities and winding conditions. Finger ridges, characterised by multiple waves oriented in machine direction, result from local grammage and moisture variations, causing troughs during winding at the pope reeler. Key contributing factors include high paper density, low air permeability, low surface roughness, and high modulus of elasticity in the z -direction. Finger ridges appear only when a pigment coating and calendering process are involved, with the calendering significantly enhancing the properties that make the paper more prone to this defect. The developed qualitative model outlines three phases of formation: Phase 1 describes the initial formation of a trough during winding due to structural inhomogeneities; Phase 2 involves the appearance of the first finger ridge in the trough due to entrapped air, moisture equalization and winding conditions; Phase 3 describes the formation of additional finger ridges symmetrically around the initial finger ridge. The preventive measures developed include ensuring uniform cross-profiles, reducing air entrainment during winding, optimizing the calendering process, and utilizing larger reel spool cores and rubberised carrying drums. Implementing these strategies can significantly reduce finger ridges, enhancing paper planarity and quality.

There is an increasing need for inexpensive biodegradable sensors that can be easily employed in networks such as the Internet of Things. Paper materials are renewable, biodegradable, and sustainable, and thus could be used as substrates for electronic sensors. This work examined two commodity cellulose materials, an envelope paper and a linerboard, as potential substrates. A multistage coating process was developed to create a smooth surface for screen-printing of sensors using inexpensive microfibrillated cellulose. Employing this process, approximately 10 g m −2 of microfibrillated cellulose was deposited, enhancing the mechanical performance of the coated materials compared with their uncoated counterparts. Sensors printed on the microfibrillated cellulose-coated substrates had reasonable electronic performance compared with those printed on a polymer substrate. Results indicate that further reducing surface roughness would be helpful for sensor performance.

CMC-β-CD-sulfaguanidine was synthesized by saturated aqueous solution method with β-CD as carrier and sulfaguanidine as inclusion compounds based on the preparation of CMC-β-CD, through single factor and orthogonal experiment, suitable conditions for the synthesis of CMC-β-CD-sulfaguanidine was obtained. The structure of the synthesized CMC-β-CD-sulfaguanidine was characterized by infrared spectroscopy, UV spectroscopy and SEM. The inclusion compounds was applied to paper reinforcement. By testing the effects of different mass concentrations of sulfaguanidine solution on the tensile strength, tearing strength, folding times, whiteness, glossiness and antibacterial properties of the paper, the suitable conditions for coating paper were found. The results show that when inclusion concentration of 3 mg/mL is coated on the paper, its mechanical properties are improved, the glossiness is slightly increased, and the whiteness is basically unchanged, at the same time, the paper has certain antibacterial properties. CMC-β-CD-SG studied in this paper has the functions of strengthening, slow-releasing, anti-mildew and antibacterial for paper, which is an innovation of paper protection material, provides the theoretical basis and data reference, as well as a new research idea and technical approach for the development of products for paper protection.

This study aims to investigate the drying process of tissue paper in depth and to analyze it comprehensively by combining experimental and simulation methods. In the experimental part, a variety of drying conditions were designed, including different air temperatures, air velocities, and bottom heating temperatures, to accurately measure the change in moisture ratio of tissue paper. Meanwhile, a mathematical model for predicting the tissue drying moisture ratio was constructed based on the experimental data, and the tissue drying process was simulated. The simulation presented the process of moisture transfer within the tissue paper visually and quantitatively. The experimental and simulation results validate and complement each other, revealing the synergistic influence mechanism of drying parameters on the drying effect of tissue paper. The results showed that the effects of air temperature, bottom heating temperature, and air velocity on the drying rate of tissue paper were in the following order: bottom heating temperature > air temperature > air velocity, and among eight drying kinetic models, the Aghbashlo model was the most suitable for describing the drying characteristics of tissue paper in thin layers, and the accuracy of the prediction model was verified by simulation.

Hemicellulose, a lignocellulosic component derived from wood or non-wood pulping, has garnered emerging research interest due to its unique property profiles, which enable its potential use as a bio-based alternative additive in paper production. Additionally, it holds significant promise for commercialization within the forest biorefinery sector. The paper reviews the articles investigated on hemicellulose and cationic hemicellulose addition in papermaking. Studies have shown that hemicellulose removal from the pulp decreased tensile strength, and hemicellulose addition reduced refining energy and improved strength properties. The effectiveness of hemicellulose addition in pulp is influenced by the molar mass of xylan. The primary challenge in using hemicellulose as a wet-end chemical is its limited ability to significantly improve papermaking properties. Therefore, it needs to be cationized to get desired performance. The cationization agents are 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC) and 2,3-epoxypropyl trimethyl ammonium chloride (EPTAC), which are used in alkaline medium. To reduce the degradation of hemicellulose, the cationization was also carried out in aqueous ethanol and relatively low alkali concentration. The application of cationic xylans to the anionic pulp surface mitigates the electrostatic repulsion, facilitate stronger inter-fiber bonding and improve papermaking properties.

To enhance the strength and antimicrobial properties of paper cultural relics, and prolong the life of paper cultural relics, it is an urgent need to prepare new material for preservation and protection of paper. In this paper, CMC-β-CD-SG was synthesized with β-CD as carrier and sulfaguanidine as inclusion complex, the suitable conditions for the synthesis of CMC-β-CD-sulfaguanidine was obtained. By testing the effects of different mass concentrations of sulfaguanidine solution on the tensile strength, tearing degree, folding times, whiteness, gloss and antimicrobial properties of the paper, the suitable conditions for coating paper were found. The results show that when inclusion mass concentration of 3 mg/mL is coated on the paper, its mechanical properties are improved, the gloss is slightly increased, and the whiteness is basically unchanged. At the same time, the paper has certain antimicrobial properties, which is in line with the principle of “repairing the old as old”. CMC-β∼CD-SG studied in this paper exhibits properties of reinforcing, slow-releasing and antimicrobial activity for paper protection, which is an innovation of paper protection material, provides the theoretical basis and data reference, as well as a new research idea and technical approach for the development of products for paper protection.

This investigation examined the development of a coating blend suitable for white top testliner paper to enhance its barrier properties and printability. The research focused on analyzing and elucidating the rheological and barrier properties crucial for the effective application of coating color. A double-coat application process was employed, with the pre-coating layer filling the rough surface profile and the top-coating layer improving the smoothness. Clay and calcium carbonate were used as pigments and latex as binder. Dispersant and thickener were also added. A barrier chemical was also incorporated in select formulations. The results indicated that the coating significantly modified the optical and barrier properties of the paper. The brightness, whiteness, and grease resistance increased, whereas the air permeability decreased. Barrier chemicals were particularly efficacious in reducing wettability and improving grease resistance. In conclusion, this study demonstrates that a well-designed coating strategy can enhance the functionality of recycled paper, rendering it a more viable option for packaging application.

The origin of dot gain comes from two primary contributions: optical and mechanical, and therefore two functions describing these contributions have been tested. These contributions are reflected in the asymmetric shape of the Line Spread Function (LSF), which is a critical parameter for analyzing the quality of printed images. This paper uses a robust iterative method to fit LSF curves, incorporating multiple single peak functions to increase measurement accuracy and enhance understanding of the phenomenon. High correlation results demonstrate the plausibility of separating these contributions and determining their percentage share within the profile. Optical dot gain, modeled using a Lorentzian function, accurately reflects its dependence on substrate properties. Mechanical dot gain, on the other hand, is described by a Gaussian function, capturing its link to printing techniques. The high correlation (R > 0.97) between experimental and modeled data validates the robustness of this method, enabling precise determination of the percentage share of each component. The results indicate that optical dot gain contributes approximately 30 % of the total, a much larger share than previously assumed. This highlights the importance of substrate selection and treatment in achieving print quality. In the context of electrostatic printing, a third, previously undetected contribution was identified. Although minor, this additional mechanical component (Gauss1) is reproducible and directly linked to the operational state of the printing machine, adding complexity to the dot gain phenomenon.

The growing environmental and health concerns associated with plastic pollution have driven the search for sustainable alternatives. This study investigated the impact of various types of cellulosic pulps and degree of refining on the production of thermoforming eco-friendly fiber-based materials as alternatives to plastics. By examining the influence pulp and fibers characteristics, the study aimed to correlate these factors with the two process parameters, formation time and drainage efficiency. Trays with a target dry weight of 31 g were produced using slurry consistency of 0.2 % and 0.8 % on an industrial molding machine. In this study, formation times required to achieve the target weight are varied from 0 to 42 s, influenced by pulp type, refining level, and slurry consistency showing that the longest time can affect the quality. Higher refining levels extended formation time, making it crucial to adjust slurry consistency to optimize production efficiency. Formation trials revealed that most pulps followed a logarithmic formation pattern at both consistencies. Dryness and drainage gain varied significantly across pulp types. Hardwood pulps exhibited the highest initial dryness, while alternative fibers like canola had the lowest, making them longer to dry. Recycled and mechanically pulped fibers retained more water due to fines content, further decreasing dewatering. Additionally, increased refining levels decreased both the initial dryness and the gain in dryness over equal drainage times. Since dryness directly influences drying time and energy consumption, optimizing pulp selection and refining strategies are essential for enhancing cost efficiency in thermoformed fiber production.

This study investigates the impact of incorporating hypo sludge (paper pulp) and human hair fiber (HHF) into M25 grade concrete to enhance its compressive strength. The research evaluates the effect of 30 % hypo sludge in cement and introducing 2 % HHF, comparing the results with conventional M25 concrete. After 28 days, compressive strength tests revealed that the modified concrete containing 30 % hypo sludge and 2 % HHF achieved a significantly higher average compressive strength of 32.91 N/mm 2 , compared to 26.08 N/mm 2 for conventional concrete. The statistical analysis, including an independent samples t -test, indicated no significant variance ( p  = 0.893) between the samples, confirming the reliability of the results. Group statistics showed consistent performance with a standard deviation of 1.67 for the modified concrete. A Bayesian Factor Test, using the Rouder method and assuming unequal variance, revealed a mean difference of 6.8289 N/mm 2 with a pooled standard error of 0.53572, yielding a Bayesian factor of 0.000. This provides strong evidence against the null hypothesis, specifying significant improvement in compressive strength. ANOVA confirmed a statistically significant difference in compressive strength between the groups ( F  = 162.489, p  = 0.000). This study highlights the potential of these novel materials for eco-friendly construction applications, providing a promising alternative to conventional methods.

The application of high-temperature passivation and evaporation crystallization for the black liquor in alkali recovery system has realized that the solids content of black liquor is as high as 70 wt%, even 80 wt%, for atomization combustion in the alkali recovery boiler. Therefore, the increase in the solids content of black liquor has become a development trend and goal of various alkali recovery systems. However, it is difficult to atomize at high solids content, and the resulting large droplets reduce the combustion efficiency of the alkali recovery boiler due to the characteristics of non-wood pulping black liquor such as bamboo pulping black liquor. In this study, we study the atomization performance of bamboo pulping black liquor with high solids content through splash plate nozzle under different injection conditions by means of CFD simulation technology. The four atomization indexes are analyzed in detail including mass flow rate, liquid film thickness, atomization cone angle and droplet size. Finally, a reasonable atomization pattern is given to prepare for subsequent combustion. The results show that the mass flow rate and liquid film thickness decrease but the atomization cone angle and droplet size increase with the increase of injection angle. The liquid film thickness is only related to the injection angle, and the atomization cone angle is not the larger the better. With the injection conditions at 35° and under 150–160 kPa pressure, not only a good atomization cone angle but also the targets of a large flow and small droplet size could be into reality, which effectively improves the ability of alkali recovery of black liquor.

The pulp and paper industry generates large quantities of Pulping Black Liquor (BL). Minimizing the chemical content in BL through effective and environmentally friendly treatment methods is therefore essential. BL contains a substantial amount of highly heterogeneous lignin, which has a complex chemical structure and a broad molecular weight distribution. Only a small fraction of this lignin is used as a dispersant, concrete additive, or binder in mining operations, while the majority is used as a fuel source. Solvent fractionation of this inhomogeneous lignin with solvents offers a promising solution to overcome these limitations. The fractionated lignin has a more controlled molecular weight and a more uniform structure, facilitating its high-value applications and reducing the environmental impact of BL. This paper reviews the conversion of lignin in BL, various methods for lignin separation, and recent advances in the use of commonly used solvents such as methanol, ethanol, acetone, dichloromethane, ethyl acetate, and ionic liquids for lignin fractionation. A novel and effective solvent-based approach for lignin fractionation from BL is proposed.

Poly(butylene adipate-co-terephthalate) (PBAT) is a synthetic biodegradable thermoplastic copolyester. In this study, we aimed to enhance lignin’s compatibility with PBAT for polymerization. Epoxidized soybean oil (ESO) was introduced as an interfacial modifier to improve lignin-PBAT interactions. A lignin/ESO/PBAT composite film was fabricated via a solvent-free one-pot method using torque rheometry. ESO formed dynamic covalent bonds between lignin and PBAT, promoting lignin dispersion. When 5 wt% ESO was added to PBAT/lignin composites (1 % lignin), tensile strength increased to 24.57 MPa (from 24.37 MPa) and strain to 956.12 % (from 922.41 %). Antibacterial assays and food freshness tests confirmed the composite’s suitability for food packaging. This work provides an eco-friendly strategy for high-performance lignin/PBAT films.

This study indicates that superior performance of novel ternary deep eutectic solvents (DES) system, formulated from choline chloride (ChCl) mixture of formic acid (Fa), pyruvic acid (Pa), and tartaric acid (Ta), exhibits remarkable efficacy in selective separation and purification of lignin from biomass. The woody biomass of Elm was pretreated with ternary of carboxylic-acid-based DES of ChCl as hydrogen bond acceptor (HBA), Lac, Fa, Pa, and Ta served as hydrogen bond donors (HBD) under the predetermined conditions. Benefitting from the efficient process, using optimized DES system (ChCl/Lac/Fa, 1:6:1, 6 h and 120 °C), it showed that the yield and purity of lignin obtained from material was 86.53 % and 90.45 %, which was more efficient than the results of binary DES system of the pretreatment process. In addition, the recovered lignin was subjected to comprehensive structural characterization employing Fourier transform infrared spectroscopy and two-dimensional nuclear magnetic resonance techniques. DES lignin was found to have a complete aromatic structure, that consisted mainly of β-β, β-O-4 bonds in different contents. These findings confirm the significant advantages of the new novel ternary DES system, which facile separated lignin from the lignocellulosic matrix under mild conditions, that providing a new reference value for efficient separation of biomass resources.