journal: Nordic Pulp & Paper Research Journal

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Zeitschrift

Nordic Pulp & Paper Research Journal

The international research journal on sustainable utilization of forest bioresources

Editor-in-Chief:

Sprache: Englisch

Erstveröffentlichung: 20. Januar 1986

Erscheinungsweise: 4 Hefte pro Jahr

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Über diese Zeitschrift

Objective

Nordic Pulp & Paper Research Journal (NPPRJ) is a peer-reviewed, international scientific journal covering to-date science and technology research in the areas of wood-based biomass:

Pulp and paper: products and processes

Wood constituents: characterization and nanotechnologies

Bio-refining, recovery and energy issues

Utilization of side-streams from pulping processes

Novel fibre-based, sustainable and smart materials.

The editors and the publisher are committed to high quality standards and rapid handling of the peer review and publication processes.

Topics

Cutting-edge topics such as, but not limited to, the following:

Biorefining, energy issues

Wood fibre characterization and nanotechnology

Side-streams and new products from wood pulping processes

Mechanical pulping

Chemical pulping, recovery and bleaching

Paper technology

Paper chemistry and physics

Coating

Paper-ink-interactions

Recycling
Environmental issues

Article formats

Research articles, reviews

Ihre Vorteile

Your benefits

State-of-the art knowledge in the broad field of wood-based biomass science and technology

Strong interdisciplinary approach

Renowned international editorial and scientific advisory boards

Publication online and print incl. online first mode

Nordic Pulp & Paper Research Journal is published in cooperation with Royal Institute of Technology (KTH), Stockholm, Sweden and run as a project at KTH with Chalmers University of Technology, Karlstad University, Mid Sweden University, Swedish University of Agricultural Sciences, Norwegian University of Science and Technology, Aalto University, Åbo Akademi University, Luleå University of Technology and University of Oulu.

Complete Archive Access

As of 2026, all De Gruyter journal subscriptions include access to every issue, from Volume 1, Issue 1 through to today, meaning subscribers can access even more research at no additional cost.

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Bamboo fiber-based self-supported flexible electrodes with in-situ deposited polypyrrole for enhanced electrochemical performance

15. April 2026

Huo Feiyu, Yang Yang, Huang Jianbo, Liu Wen, Chao Lumen

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With currently enormous and growing demand for portable electronic devices, flexible electrodes have garnered significant research attention. Cellulose fibers with low-cost, environmentally friendly, renewable and flexible properties have become a promising trend for flexible substrates. Exploring the influence of different plant fibers on various properties of electrodes is of positive significance to the selection of raw materials for flexible electrodes. However, the existing work mainly utilized plant fibers as support material, with limited exploration of their effects on the electrical and electrochemical properties of flexible electrodes. Herein, we successfully fabricated self-supporting polypyrrole (PPy) cellulose-based flexible electrodes through in situ polymerization of pyrrole on the surface of different types of plant fibers with liquid phase redox combined with wet papermaking process. Among all tested plant fibers, the bamboo fiber-based self-supporting flexible electrode with a PPy loading of 30 g m −2 exhibited excellent conductivity (4.02 S cm −1 ) and outstanding electrochemical performance, delivering an areal capacitance of 1,490 mF cm −2 at 5 mA cm −2 , benefiting from bamboo fiber’s unique morphology. The development of high performance flexible electrode with bamboo fiber not only offers a green and cost-effective approach but also expands the application potential of plant fibers in flexible electronic devices.
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Effect of beating on the Paper-making properties of bagasse cellulose fibers

14. April 2026

Zhihong Ou, Jizhen Huang, Kai Li, Jianquan Hu, Yuxin Liu

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The effect of beating on the paper performance of bagasse cellulose fibers was investigated by analyzing changes in morphological parameters (fiber length and fines content), physical properties (tensile strength, breaking length, and tensile force), water retention value (WRV), cellulose crystalline structure, and pore structure of the fibers. The results indicate that the fines content increased by 4.98 % at 80°SR compared with the unbeated sample. Tensile strength, breaking length, and tensile force increased with the beating degree. WRV also increased with beating, showing a rise of 62.89 % after the first refining stage. In contrast, the cellulose crystallinity first increased and then decreased with beating intensity, being 3.1 % lower at 80°SR compared with that at 13°SR. FTIR spectra indicated no significant changes in the functional groups of bagasse cellulose during the beating process. With increasing beating intensity, the pore size distribution gradually shifted toward larger pores, leading to an increase in the average pore volume.
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Research on the paper cultural relics reinforced by various cellulose solutions

14. April 2026

Jianan Liu, Yulong Peng, Huiming Fan, Yibin Lin, Wanqi Zhou

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Paper relics tend to deteriorate and become brittle during long-term preservation. Cellulose as a major component of paper is commonly utilized for reinforcing paper materials. In this study, the solutions of cellulose were prepared using three different solvents: 1-butyl-3-methylimidazolium chloride ([Bmim]Cl),1-butyl-3-methylimidazolium acetate ([Bmim]Ac) and N-methylmorpholine-N-oxide hydrate (NMMO/H 2 O). A dyeing and labeling method is employed to demonstrate that these solutions could effectively penetrate into the interior of the paper and form regenerated cellulose. Scanning electron microscopy (SEM) analysis revealed the formation of a continuous cellulose layer on the surface of the treated paper samples. All samples were subjected to the same reinforcement procedure followed by accelerated aging tests. The mechanical properties, whiteness, and chromatic aberration of the samples were evaluated. Results indicated that the solution of cellulose dissolved in [Bmim]Ac achieved the most favorable balance between reinforcement efficacy and preservation of the original paper properties, when the amount of cellulose added was 6 g/m 2 , the tensile index increased by 26.16 %, with a chromatic aberration value of 1.86 observed before and after reinforcement. That study provides a new approach for the application of cellulose solutions in the conservation of paper-based cultural heritage.
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The influence of xylanase-treated bleached broadleaf pulp as a substitute for flax pulp on the properties of slim cigarette paper

7. April 2026

Haiying Wei, Min You, Xiaochen Shen, Guoliang Zhao, Linli Qin, Hao Wu, Jianguo Bai, Chengwen Zhu, Hao Ren

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This study addresses the high cost of imported flax pulp (FP) in fine cigarette paper production. It was found that the key difference between bleached hardwood kraft pulp (HBKP) and FP lies in their hemicellulose components. Consequently, commercial HBKP was treated with xylanase under optimized conditions, reducing its xylose content by up to 18.5 %. Based on this process, the same enzymatic treatment was applied to the mixed pulp in cigarette paper production lines, yielding even better results. Enzyme-treated bleached hardwood kraft pulp (EHBKP) was used to partially replace FP (0–50 %) in cigarette papermaking. The effects on the physical properties and pyrolysis characteristics of the resulting paper were comparatively studied. The results showed that when EHBKP replaced 10–50 % of FP, the tensile strength of the paper increased by up to 15.6 %, while the tear index decreased by only 10.9 %. Py-GC/MS analysis revealed that when EHBKP replaced 10 % of FP in cigarette paper production, benzene compounds generated from paper pyrolysis at 900 °C decreased by 23.7 %, and phenolic compounds continued to decrease with increasing replacement levels. In conclusion, replacing 10–20 % of FP with EHBKP significantly reduces harmful pyrolysis products while maintaining essential physical properties, combustion performance, and paper thermal stability.
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Trade-offs between sulfidity and physicochemical properties of recovered Eucalyptus kraft lignin

6. April 2026

Ana Claudia G. Batista, Humberto de J. Eufrade-Junior, Scheila T. da Silva Paes, Luciana Duque Silva, Francides G. da Silva Júnior

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Kraft lignin is a promising biopolymer for product diversification in the pulp and paper industry and integrated biorefinery concepts. This study evaluated the effect of white liquor sulfidity (0–40 %) on Eucalyptus spp. kraft lignin recovered by acid precipitation (CO 2 and HCl). The recovered lignins were characterized in terms of elemental composition, thermal behavior, and chemical structure. While sulfidity had a limited impact on the overall thermal stability and decomposition profiles, it strongly affected pulping performance, including total yield, H-factor, and cooking severity. Notably, the sulfur and sodium contents of the recovered lignin varied systematically with sulfidity, reflecting changes in the delignification pathway and black liquor chemistry. Higher sulfidity enhanced sulfide-assisted lignin fragmentation, leading to the incorporation of sulfur-containing functionalities (e.g., thiols and mercaptans) and a reduced dependence on sodium for lignin solubility. The outcomes provided insights into how sulfidity can influence lignin properties with implications for its subsequent use in advanced materials applications.
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Production of high-quality dissolving pulp from eucalyptus via a prehydrolysis-free process for Lyocell fibers

19. März 2026

CHEN GONG, Chunzu Cheng, Nan Li, Jianping Ni, Zhenjun Xue, Xinqi Wang, Bin Yang, Shujie Fan, Yu Zhang, Zhenhua Su

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This study developed a flexible pulping process as an alternative to conventional pre-hydrolysis for producing dissolving pulp. By implementing an optimized cooking profile, effective hemicellulose removal was achieved while maintaining a high pulp yield. Building on this optimized cooking, an integrated control strategy was established across the entire process chain – cooking, bleaching, and post-treatment – enabling precise regulation of pulp properties. The resulting pulp exhibited performance comparable to international benchmark products, with an overall enhanced process yield. The product demonstrated superior purity (higher R 10 and R 18 ), alongside a marginally lower whiteness and acceptably elevated metal ion content compared to an international benchmark sample. Furthermore, this pulp was successfully spun into cellulose fibers that meet the premium-grade standards for Lyocell, thereby validating the feasibility of the proposed pre-hydrolysis-free route for manufacturing Lyocell-grade pulp.
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Study on the mechanism of inhibition of bagasse fibres hornification by microwave bulking

17. März 2026

Qurui Yang, Jizhen Huang, Wanruo Lei, Zinuo Meng, Yuxin Liu

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Using bleached, undried bagasse pulp as raw material, this study investigated the inhibitory effect of microwave expansion on secondary fibre hornification. The optimal process parameters were determined through optimisation: microwave power: 900 W, temperature: 70 °C, duration: 2 min, solid-liquid ratio: 1:10, and expansion agent dosage 10 %. Results demonstrated that this treatment significantly enhanced fibre water retention and paper strength. Water retention of reused bagasse fibre increased by 18.89 % after a single reuse and remained elevated by 6.34 % after five reuses. Mechanistic analysis revealed that microwaves disrupt inter- and intramolecular hydrogen bonds in cellulose, reducing crystallinity, microcrystal size, and primary fibre cross-sectional area while disintegrating pseudocrystalline regions. This inhibits hornification, providing theoretical and technical support for efficient reuse of non-ligninous fibre.
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Enhancing recycled-paper quality using cellulose nanocrystals from pineapple leaf waste

6. März 2026

Averroes Piliang, Nico Sihotang, Muhammad Ibadurrahman, Sri Rahayu, Zhihao Yen, Ronn Goei, Refi Ikhtiari, Alfred Tok, Saharman Gea

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Pineapple leaves, often found as waste in North Tapanuli District, Sipahutar District, contain high levels of cellulose, making them a potential source for extracting cellulose nanocrystals (CNC). This study employs the acid hydrolysis method, followed by ultrasonication, to produce CNC, a process known for its simplicity and effectiveness in removing amorphous cellulose. The Fourier transform infrared spectroscopy (FTIR) analysis at a wavenumber of 1,358 cm −1 , associated with S=O vibrations, indicates esterification during hydrolysis. Transmission electron microscopy (TEM) reveals that the extracted CNCs exhibit a rod-like structure with a diameter of 5.18 ± 1.61 nm. X-ray diffraction (XRD) results show a crystallinity index of 78 % and a crystal size of 2.35 nm. The CNCs were incorporated into used newspaper pulp at varying concentrations (0, 1.5, 3, 5, and 8 |wt%). The findings demonstrate that CNC addition enhances the mechanical properties of the paper, including grammage, tensile strength, tear index, and crack index, primarily due to hydrogen bonding interactions between CNCs and pulp fibers. The optimal improvement was observed with a 5 | wt% CNC addition, significantly increasing tensile strength, tear index, and crack index of the recycled paper.
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Evaluation of mixtures of pine and eucalypt wood for the production of bleached kraft pulp

3. März 2026

Bruno de Freitas Homem de Faria, Fernando José Borges Gomes, Rubens Chaves de Oliveira, Diego Pierre de Almeida, Paula Santana Barbosa, Thayanne Caroline Castor Neto

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Blending wood species can combine complementary fiber attributes in a single pulp. This study evaluated kraft pulping of Pinus sp . and Eucalyptus sp. chip mixtures and the bleachability of the resulting pulp. Pulping was performed to reach Kappa 20 ± 1 using eucalypt/pine blends at 90/10, 80/20, 70/30, and 60/40 (oven-dry mass). A 100 % eucalyptus pulp served as the Reference. All pulps were bleached with an ECF sequence. As pine proportion increased, the H-factor rose from 481 (Reference) to 1,170 at 40 % pine. Brown pulp viscosity showed a decreasing trend with increasing long fiber content. Bleaching reacted in such a way that pulps with higher long fiber content and lower bleachability required higher active chlorine loads. Overall, kraft pulping of these mixtures proved technically feasible. However, these operational trade-offs should be weighed against potential property gains from longer fibers, so that chip-mix strategies can be tuned to balance product performance with pulping and bleaching.
Open Access
Quantification of damage generated during Fortuna splitting of paperboards

26. Februar 2026

Adam Attemalm, Mikael Nygårds

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Accurate ply-specific properties are critical for predictive modeling and process optimization in paperboard manufacturing, yet the widely used Fortuna splitting technique may alter mechanical properties. This study addresses the gap by quantifying the damage introduced when three-ply paperboards are separated into individual plies using a Fortuna splitting machine. While grammage remains unaffected, splitting increases surface roughness and slightly inflates measured thickness, requiring correction for accurate laminate modelling. Tensile tests and curve-fitting reveal that splitting reduces the elastic stiffness and yield strength of free-laid plies compared to intact boards. Average reductions were determined as 11 % in tensile stiffness and 7 % in yield strength. Damage distribution is highly non-uniform: the middle ply exhibits the greatest degradation, up to 29 % stiffness loss in CD, while the outer plies are less affected. Splitting quality and direction significantly influence the magnitude of damage; cuts following interfaces minimize damage, whereas cuts propagating through plies increase bond disruption. By introducing damage-compensated properties, the intact board response can be accurately reconstructed from ply data, allowing for reliable finite element modeling. These findings underscore the importance of controlled splitting procedures and correction factors when utilizing free-laid ply properties for design and process optimization.
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Changes from lignin to lignin derivatives during prehydrolysis of lignocellulose

17. Februar 2026

Nianjie Feng, Xin Wang, Xiaotian Zhu, Xu Yang, Qian Wu

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Lignin derivatives produced in prehydrolysis have hindered the conversion and utilization of carbohydrates. Using Masson pine, poplar, and wheat straw as raw materials, the changes from lignin to lignin derivatives during prehydrolysis were systematically studied under the conditions of hydrolysis temperature (160 °C and 180 °C) and holding time (30 min and 120 min). The results showed that Masson pine lignin was easy to condense, while wheat straw lignin was more prone to degradation. A part of the dissolved lignin was adsorbed on the fiber surface after recondensation, especially at high prehydrolysis temperature. The other part condensed with carbohydrate to form lignin-carbohydrate complex, but it was not stable during long-term hydrolysis. For the specific target products, the two undesirable lignin derivatives can be controlled by designing the prehydrolysis temperature and holding time.
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AI-driven development of biodegradable flushable wet wipes from upcycled household organic waste: formulation, performance, and predictive optimization

6. Februar 2026

Shalini Kannan, Thavasilingam Kannan, Muruga Boopathi Muthupandi, Karthi Marimuthu

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Innovative, sustainable alternatives are needed in light of the growing environmental concerns surrounding synthetic single-use wipes and the growing amount of organic waste generated in households. This study describes the creation and refinement of biodegradable flushable wet wipes made from recycled Fruit and Vegetable Waste (FVW) combined with naturally occurring antimicrobials such orange peel oil and Coleus amboinicus . Thermochemical pulping, sheet casting, and bio-lotion impregnation were used to create the wipes, which produced a plant-based matrix with encouraging structural and sanitary qualities. The wipes thermal stability, structural integrity, and moisture permeability were validated by physicochemical characterisation using FTIR, DSC, TGA, and WVTR analysis, making them appropriate for flushable use. Significant inhibitory zones against Pseudomonas aeruginosa , Escherichia coli , and Staphylococcus aureus were found in antimicrobial testing, exceeding commercial wipes. In order to forecast important performance outcomes based on material composition, a machine learning framework was also put into place. Fibre and phenolic content emerged as the main predictors for WVTR and antibacterial efficacy, while Random Forest models produced high predictive accuracy (R 2 >0.90). In order to enable scalable, low-impact bio-product creation, effort combines green chemistry, and artificial intelligence in a circular, data-driven approach to the production of eco-conscious hygiene products.
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The relationship between wood of eight poplar clones and handsheet properties based on multiple linear regression model

28. Januar 2026

Xiangkun Meng, Chunhao Du, Zhanshuo Wang, Hui Gao, Liang Zhou, Wenli Gao, Ying Guan

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The chemical composition of poplar wood showed strongly influences on pulping efficiency and paper performance, yet systematic predictive frameworks for clone evaluation remain limited. In this study, eight representative poplar clones widely cultivated in China were subjected to Kraft pulping and sheet preparation. Comprehensive characterization was performed including wood chemical composition, pulp yield, Kappa number, viscosity, and paper properties. 108 poplar yielded the highest burst index (4.79 kPa·m 2 ·g −1 ) and tear index (18.12 mN·m 2 ·g −1 ). The Ridge-regression models predicted pulp yield, Kappa number, viscosity and paper strength with R of 0.90–0.99, RMSE ≤ 0.33 and MAE ≤ 1.20. From the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) analysis, 108 poplar was the best overall clone (NCi = 0.230). To elucidate the interrelationships among wood chemistry, pulp behavior, and paper properties, twelve variables across three categories were analyzed. The Ridge regression was employed to overcome multicollinearity and achieved reliable prediction (R = 0.90–0.99, with low RMSE and MAE). Multi-criteria ranking using the TOPSIS further identified the 108 poplar as the best-performing clone overall. These findings established an effective integration of predictive modeling and decision analysis, offering a practical framework for clone selection and optimized utilization of poplar resources in the pulp and paper industry.
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Association of coconut wax and nanolignin for eco-friendly packaging coating: study of barrier, surface, and mechanical properties

21. Januar 2026

Isabella Pereira Nunes, Adriano Reis Prazeres Mascarenhas, Mário Vanoli Scatolino, Gustavo Henrique Denzin Tonoli, Rafael Carvalho do Lago, Dayane Targino de Medeiros, Felipe Gomes Batista, Thiago Cardoso Silva, Rafael Rodolfo de Melo, Maressa Carvalho Mendonça, Saulo Rocha Ferreira, João Moreira Neto, Keoma Defáveri do Carmo e Silva

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Plastic packaging causes damage to ecosystems, especially marine ones, due to the accumulation and difficulty of environmental degradation. Alternatively, biopolymers are promising due to their biodegradability and increased safety. Coconut wax is valued for its clean burn, low toxicity, and for being a sustainable alternative to other waxes, such as paraffin. Nanolignin (NL) is a nanometric material obtained from lignin, the second most abundant renewable natural biopolymer on the planet after cellulose. The effects of coconut wax-based coatings containing different proportions of nanolignin on the properties of Kraft paper were investigated. Emulsions with 0.5 %, 1.0 %, 1.5 %, 2.0 %, and 2.5 % NL were applied in two layers on the paper. The samples of coated papers were evaluated by microstructure, wettability, water vapor barrier, and mechanical properties. Peaks associated with saturated fatty acids were observed in the 3,100 cm −1 and 2,800 cm −1 bands. Only the coating with 0.5 % NL obtained cohesive layers, and the other emulsions penetrated the paper. The emulsions with 2.0 % and 2.5 % NL showed the lowest water absorption (∼28 g/m 2 ) and wettability (∼0.03°/s). On average, compared to the control, the coatings reduced tensile strength by up to ∼38 % and Young’s modulus by up to ∼43 %. Compared to the control, the water vapor permeability of the coated papers was lower (450–800 g/m 2 day). The results highlight the potential of coconut wax associated with lignin valorization for paper coating, considering the industrial requirements for moisture-sensitive products.
Open Access
Paper strength correlates with hornification for kraft pulps dried at different temperatures

21. Januar 2026

Björn Sjöstrand, Sandra Mellroth, Gunnar Henriksson

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This study examines the impact of hornification on the strength of paper made from chemical pulps. Two key aspects are examined: how varying degrees of hornification influence the mechanical properties of paper sheets, and how temperature affects hornification in papermaking pulps when water remains within the fibre structure. Experiments were conducted on hardwood and softwood kraft pulps that were dried and heated under controlled conditions. The results revealed that hornification reduces the strength of paper made from three different types of pulp. A local minimum of hornification and local maxima of tensile strength occurred around 40–60 °C. A strong linear correlation was observed between decreased tensile strength, decreased water retention, and the hornification ratio. Temperature treatments applied without water removal did not affect the water retention value (WRV) or the strength of the paper. This confirms that water removal is essential for hornification and strength loss to occur. These findings refine our understanding of hornification, suggesting that careful process control during drying can exploit the positive effects of moderate drying while minimizing hornification, and thus, the risk of excessive fibre closure. Such control strategies could improve strength optimization in industrial pulp and paper manufacturing.
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Effect of sample length and width on Young’s modulus value of paperboard obtained from flexural vibration test

9. Januar 2026

Hiroshi Yoshihara, Masahiro Yoshinobu, Makoto Maruta

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The Young’s moduli in the machine (M) and cross-machine (C) directions, denoted as E md and E cd , respectively, were determined for two flat paperboard samples with a thickness of 1 mm using a flexural vibration (FV) test. During the tests, the length ( L ) and width ( B ) of the samples were varied in the ranges of 60 ≤ L ≤ 140 mm and 10 ≤ B ≤ 50 mm, respectively, and their effects on E M and E C were examined. Before the FV tests, finite element calculations were performed, and the results were compared with those obtained from the subsequent FV tests. The sample configurations had a greater effect on E md than on E cd . When the sample length was aligned in the M direction, saddle-shaped deformation increased with the increasing B value, reducing the accuracy of E md . However, statistical analyses revealed that sample configurations affected E md and E cd , and the optimal ranges of L and B were 80 ≤ L ≤ 120 mm and 10 ≤ B ≤ 30 mm, respectively.
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Deacidification of paper-based relics by calcium hydroxide nanoparticle suspension

7. Januar 2026

Chaoye Liang, Tingting Lei, Kexin Gao, Nuo Xu, Xian Cao, Donglin Tang, Guangzhao Zhang

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Historic paper relics are crucial for preserving cultural heritage, but acid-catalyzed cellulose hydrolysis causes severe deterioration. Traditional alkaline deacidification struggles with long-term protection, especially for highly acidified papers. This study developed stable Ca(OH) 2 nanoparticles suspensions (hydrodynamic diameter 100–200 nm, polydispersity index 0.17) by reacting calcium methoxide with water in 95 % ethanol under ultrasonic treatment. The acquired nanoparticle suspensions remained stable for 70 days. When applied to deacidified acidic paper, it raised the pH from 4.2 to 9.0, and the pH maintained at ∼7.3 after one-week artificial aging under the constant conditions (80 °C, and 65 % relative humidity). X-ray diffraction revealed the transformation of calcium compounds during deacidification, while SEM-EDS/AFM confirmed uniform calcium distribution forming protective surface layers. Cross-sectional analysis via SEM showed nanoparticles filling paper microfiber gaps without altering structural topography. This nanoparticle-based approach effectively neutralizes acidity while preserving paper integrity, offering a promising solution for long-term conservation of historical documents.
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The role of high-energy milling treatment for improving characteristics of areca leaf sheath lignin

7. Januar 2026

Muhammad Rasyidur Ridho, Sehrish Javaid, Jayadi, Pati Kemala, Apip Amrullah, Puji Rahmawati Nurcahyani, Chandrasekaran Dhanush, Lee Seng Hua, Widya Fatriasari

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This research examined the effects of high-energy milling (HEM) on the physicochemical and structural properties of lignin derived from the areca leaf sheath (ALS). Lignin was extracted from black liquor with the incorporation of 20 % phosphoric acid (H 3 PO 4 ), thereafter undergoing drying, grinding, and sieving to achieve a consistent powder. The characteristics of the lignin samples treated by HEM under regulated conditions were later examined using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and morphological analysis. FT-IR analysis indicated substantial changes in functional groups, implying partial depolymerization and heightened exposure of hydroxyl and carbonyl functionalities. The XRD patterns indicated a notable decrease in crystallinity, implying that mechanical forces during milling generated an amorphization impact. These structural disruptions may augment the reactivity and surface area of lignin, confirming that HEM is an effective physical method for modifying the characteristics of ALS-derived lignin. The findings support the increased use of agricultural leftovers using eco-friendly and sustainable processing techniques.
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Selection of the elite genotype among the five different Eucalyptus hybrid pulpwood clones for social and farm forestry

16. Dezember 2025

Sowmya Kuppusamy, Thamaraiselvi Kaliannan

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To meet the raw material demands of the paper industry, social and farm forestry programs require the selection of improved Eucalyptus clones with superior wood properties. In this study, five improved Eucalyptus hybrid clones 9, 21, 4, 16, and 41 were evaluated. These clones were selected on the basis of their field performance. Clone ITC 2315, which performs well in commercial pulp mills, was used as the reference clone. The objective of this study was to assess the kappa number, pulp yield, and pulp properties of the five test clones and compare their performance with the reference clone. Kraft pulping of the extracted wood chips was carried out using a 19 % active alkali charge at 165 °C. Clones with higher pulp yield exhibited lower kappa numbers, indicating effective lignin removal during pulping. The resulting kraft pulps were bleached using a sequence of 70 % chlorine dioxide, 1 % hydrogenperoxide, and 30 % chlorinedioxide. Handsheets were prepared from both the unbleached and bleached pulps, and their properties including brightness, tensile strength, burst index, bulk, and opacity were evaluated. Clones 41, 16, 21 demonstrated higher pulp yields than the reference clone and showed favourable pulp and paper properties. These results suggest that these inter-hybrid clones are more suitable for papermaking applications.
Open Access
Simulations of lateral stress variations in a flexographic print nip

3. Dezember 2025

Cecilia Rydefalk, Anton Hagman, Artem Kulachenko, Sofia Thorman

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Contact printing, calendaring, and coating of packaging paperboard are standard industry processes that utilize rolling nips. The pressure pulse, maximum pressure, and duration have been extensively studied regarding its effect on the substrate and how it can be changed and controlled to achieve the desired effect. The present study considers lateral variations of the stress in a rolling process. A parametric study of the surface roughness, substrate stiffness, cylinder cover stiffness, and changed nip engagement or impression is performed using Finite Element Modelling. The simulation shows that a smooth surface does not completely negate the effects of the structural thickness. The impression has the most significant impact, and the combination of roughness and non-linear material means that the pressure distribution can change drastically, not just the maximum pressure pulse. Additionally, different combinations of settings can achieve the same mean pressure pulse but have very different stress distributions. E.g. changing the surface roughness will have a significant effect on the pressure variations, but the effect on the pressure profile shape is negligible.

Journal Impact Factor	1.2	2024, Journal Citation Reports (Clarivate, 2025)
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