A novel cellulose nano material was prepared through a controlled Fenton oxidation process utilizing hydrogen peroxide and ferrous ions. The reaction parameters enabled ferrous-catalyzed oxidation, which combined with mechanical treatment resulted in an effective fibrillation of cellulose fibers. Optical microscopy images provided a visual comparison of fiber morphology between untreated hardwood pulp and Fenton-treated samples, clearly illustrating the fibrillation effect. The samples were evaluated for fiber drainage behavior, and conclusions about accessibility and the extent of fibrillation were made. Measurements of the surface charge of the samples revealed an increase in negative charges originating from added carboxyl groups, which is essential for the dispersing and stabilization of cellulose nano fibrils and micro-fibrillated cellulose (CNF/MFC). Fourier-transform infrared spectroscopy (FTIR) confirmed the introduction of the carboxyl groups due to the Fenton treatment. The CNF/MFC material was used as paper coatings, without adding additional materials. The coated samples underwent analyses of permeability and roughness, revealing possibilities for enhancements in barrier properties and hydrophobicity. The results emphasize the ability of Fenton oxidation in generating high-quality small scale cellulosic materials with customized functionalities, underscoring their potential application in advanced coating technologies and sustainable material innovation.

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.

In the past decades, substantial research efforts have been directed towards increasing the availability of renewable and recycled raw materials. Lignin, one of the most abundant natural polymers, constitutes a vast, renewable, and largely untapped source of aromatic structures. In addition, it is one of the most abundant renewable sources of carbon. Despite the countless research projects aimed at valorizing kraft lignin, the largest source of industrial lignin, relatively few commercial kraft lignin products have emerged. Simultaneously, lignosulfonates represent a commercially successful range of products with a steady and growing global market. This paper reviews the current outlook of technical lignin research, including common misunderstandings, and discusses various factors that have hampered the use of lignin as a renewable source of materials and chemicals.

Chemical modification of cellulose can alter the properties of cellulose, creating endless application areas. Accessibility and reactivity are key to the successful modification of cellulose. However, its crystalline structure results in poor and uneven reactivity, which can be amplified during processing, such as hornification. In this work, we have dissolved cellulose in cold alkali and reprecipitated it with acid to form a highly swollen structure, herein called swollen cellulose. The swelled structure bound large amounts of water, and upon drying the cellulose became severely hornified. Hence, various drying methods to mitigate hornification were evaluated, including freeze-drying, acetone drying, and drying in the presence of glycerol. The degree of hornification was indirectly assessed by measuring the cellulose samples' water retention value (WRV), which reflects their ability to reswell in water. The alternative drying methods increased the WRV by 270–650%, demonstrating a significant reduction in hornification. In comparison, air-drying reduced the WRV by 30%. Electron microscopy evaluation showed that the structure of cellulose differed depending on the drying method and indicated that the remaining cell wall structures were lost by the swelling, and air-dried swollen cellulose appeared to have a more compact structure than freeze-dried or acetone-dried samples. Water retention value in the presence of the sodium sulfate indicated that hydrophobic surfaces play a role in cellulose and that swollen cellulose has more exposed hydrophobic surfaces compared to the crystalline reference material.

Most manufacturing processes for materials from cellulose-based materials deal with huge amounts of water, the interactions of water within the raw material (cellulose) both enable exciting properties as well as limit the rates of production. In the production of tissue paper materials, water content in the pulp is as high as 99.8% when fed into the paper machine, and almost all this water must be removed efficiently and fast. This work presents Novel, easy-to-use, numerical models for predictions of the dewatering of tissue in high vacuum suction boxes and through air drying (TAD) molding. The numerical models were based on and compared with previously published experimental results of vacuum dewatering from laboratory equipment and validated against four separate pilot paper machine trials. The purpose of this study was to establish an accurate, easy-to-use numerical model varying fiber- and machine parameters used in tissue manufacturing to enable the evaluation of new materials and dewatering strategies for energy efficiency investigations. The results indicate that the developed dewatering model could predict the dewatering behavior for both conventional vacuum dewatering and TAD molding using the same set of fitting parameters. The method of developing the numerical models presented can be used for machine optimization and energy efficiency improvements of vacuum dewatering elements in papermaking processes in general.

The production of natural greaseproof paper is a highly energy extensive process typically involving intense refining of softwood pulp in order to yield a low porosity, high density sheet, with low air permeance. This study evaluates the addition of Eucalyptus globulus hardwood fibers to the softwood stock as an approach for reducing the specific refining energy needed on both machine-made, and laboratory-made papers. This addition reduced the average fiber dimensions, leading to a net saving of up to 160 kWh per ton produced paper within the refining, while either maintaining or improving the pulp and paper properties.

In the manufacturing of cellulose derivatives, improving cellulose accessibility is essential for achieving a high product quality. In this study, endoglucanase enzyme treatment was applied prior to the cationization reaction to enhance the accessibility of hydroxyl groups for the production of cationized dialdehyde cellulose (CDAC). A range of enzyme dosages (0.09–45.00 ECU/g) was tested, and their effects on the swelling behavior and surface charge density of the final product were evaluated. The surface charge density of the ultimate cellulosic derivative confirmed its cationization and was proven to enhance the charge density of cationized dialdehyde cellulose (35% increase) compared to untreated pulp with enzyme. Additionally, the modified cellulose exhibited a significantly higher swelling capacity than regular pulps. These findings suggest that enzymatic pretreatment can enhance fiber reactivity and support a more sustainable and efficient production of cellulose-based derivatives, offering a promising potential for commercial applications.

Pulp fiber lengths are important in the mechanical behavior of paper and paperboard materials. The length affects the total number of bond sites in fiber networks and thus indirectly the paper strengths. In a case study at Mölnbacka Sweden, fiber lengths of wood samples from 38-year-old trees of Norway spruce (Picea abies) with fast height growth were investigated. The fiber length of the samples was compared with literature values, and some reference example material. The hypothesis was that the sampled trees with fast height growth may have longer fibers, and thus provide longer pulp fibers, compared to lengths previously reported. The work highlights and critically examines the impact of different preparations, measurements, and analysis methods of fiber lengths. The results from this study show that the 21-year-old sampled wood had longer fibers than expected when compared to previous reports for Norway spruce wood grown in Sweden. The samples also showed to have skewed distributions with proportionally more long fibers than expected, also shown by higher mode values to describe central tendencies. About 75 % of the manually measured Mölnbacka fibers were longer than 3.1 mm with a mode value of 3.77 mm.

This study aimed to investigate the relationship between hornification and the accessible surface area for cellulosic pulps in order to obtain a better understanding of the mechanisms behind hornification. Hardwood and softwood paper grades were hornified to varying degrees by sequential high-temperature drying cycles, and the degree of hornification was assessed by water retention, which was shown to decrease linearly and to correlate closely with accessible surface areas measured by xyloglucan adsorption for both hardwood and softwood pulps. The relationship between hornification ratios and accessible surfaces for xyloglucan adsorption shows different linear relationships above and below 100 °C, supporting the hypothesis of different hornification mechanisms at different temperatures shown in the previous literature. Furthermore, hornification was shown to cause a reduction in fiber width for softwood pulps and a reduction in fiber length for hardwood fibers.

Through Air Drying (TAD) technology enhances high-quality tissue-grade paper production by shaping a wet paper web on a structured fabric using vacuum or molding boxes, followed by hot air displacement drying over TAD cylinders. This study uses CFD modeling with COMSOL Multiphysics to understand drying rate during the molding process better. Two-dimensional models of paper sheets estimated solid content over vacuum time. Tissue samples were generated using COMSOL's interface with MATLAB, enabling a random fiber distribution. Fluid flow and moisture transport were simulated by coupling the Navier-Stokes and advection-diffusion equations, while Darcy's law with inertial correction described fluid migration within fibers, considering equilibrium between moist air and liquid water. Simulations examined the impact of refining levels and fiber compositions for basis weights from 15 to 30 g/m2. Material properties, including porosity and permeability, were calibrated with laboratory tests and validated in pilot experiments. Results showed that increased refining of softwood pulp significantly affects porosity and initial dryness, achieving reasonable agreement between predicted and actual tissue dryness. The calibrated models could be a first step to improve energy efficiency in TAD processes, paving the way for more sustainable tissue-making methods.