Band 38, Heft 3

Development of three-dimensional continuum models for paperboard is an active field and the need for reliable measurements to calibrate and validate such models is evident. An experimental device and protocol for cyclic out-of-plane loading is developed. This loading sequence is present during converting operations of paperboard. The experimental tests reveals that the commonly observed soft initial non-linear response during out-of-plane compression is a structural effect that stems from the surface roughness rather than being an inherent material behavior. A gluing procedure, used to perform cyclic out-of-plane loading, is mitigating the effect of the surface roughness. Several novel cyclic loading experiments are performed, alternating between compression and tension which indicates that fiber bonds are not recovered in compression after they have been broken through delamination. Measurements also show that the transition in compression and tension is continuous, hence the use of a switch function present in a number of constitutive continuum models for paperboard is deemed questionable.

The interlaminar shear modulus of cardboards was measured using torsional vibration (TV) and flexural vibration (FV) methods. In the TV method, the sample widths were decreased during the tests, and the interlaminar and in-plane shear moduli were determined using the data obtained based on the different widths. By contrast, in the FV method, the resonance frequencies from the first to third FV modes were measured using samples of various lengths, and the interlaminar shear modulus and Young’s modulus in the length direction were calculated using Timoshenko’s vibration theory. In addition to the experiment, modal analyses based on the finite element (FE) method were performed, and the sample configurations used to accurately obtain the interlaminar shear modulus were experimentally and numerically investigated. The TV method did not allow the interlaminar shear modulus to be obtained appropriately because the vibration behavior often deviated from that theoretically derived by the TV equation. By contrast, the FV method allowed the interlaminar shear modulus to be obtained appropriately for a wide range of sample lengths.

The hemicellulose was extracted from the Stachys floridana Shuttlew. ex Benth by ultrasonic-assisted, fractional alcohol precipitation method, mixed with chitosan solution, and coated on the surface of the paper with three layers, to explore the effect of its morphology, thermal stability, barrier, mechanical properties of coated paper. The results showed that the gas barrier property of the paper coated with hemicellulose – chitosan mixed solution decreased from 180 mL/min to 0.265 mL/min, the water barrier property increased from 0 to 84.8°, and the oil barrier property increased from 0 to Kit nº11. The tearing degree of paper increased by 9.2 %, the folding resistance increased by 1296.6 %, dry and wet tensile strength and dry and wet rupture resistance were also significantly improved. The thermal stability mixed solution coated paper is slightly lower than the base paper, but higher than the pure chitosan coated paper. The prepared S. floridana Shuttlew. ex Benth hemicellulose – chitosan blend coating has good barrier property and mechanical properties, and has a wide application prospect.

The aim of this work is to investigate the influence of fiber fibrillation and fines on the pore structure of well-defined regenerated fiber sheets as well as the water flow through the sheet. For this purpose, sheets were produced with refined, fibrillated fibers only, with unfibrillated fibers and fines, as well as with fibrillated fibers and fines. Next, the samples were analyzed by brightfield and fluorescence microscopy, mercury porosimetry, and an ascending test. Both the fibrils and the added fines reach into the pores between the fibers or are deposited there. As a result, pore size decreases and capillary flow slows down. The two effects overlap when the fiber surface is fibrillated and fines are present. Sheets with thicker fibers form a pore structure with larger pores in between the fibers. However, such a change in pore size has no significant influence on the flow of water through the sheet in the performed ascending tests. It is shown that a statistical model with the parameters fibrillation and fines content can be used to describe the ascending rate nearly as well as the Lucas–Washburn equation. Consequently, the equation could be improved by the addition of further fiber and sheet properties.

As a cultural carrier of historical inheritance, paper has high cultural, historical and scientific research value. But with the passage of time and the change of the environment, many paper are aging and damaged. In order to protect the paper, epoxy cyclohexane/chitosan/methyl methacrylate composite material for paper protection was synthesized by radical grafting polymerization with potassium persulfate (KPS) as initiator and disodium hydrogen phosphate (DSP) as buffer reagent. Through single factor experiment, the synthetic condition was obtained as follows: 3 g of monomer dosage, 7.5 mL of initiator, 80 °C of reaction temperature, 3 h of reaction time. The aging test showed that the coating material could obviously improve the mechanical properties and anti-aging properties of paper. The reversibility experiment shows that the composite material has certain reversibility. The acid and alkali salt resistance experiment shows that the coating material could effectively resist external acid and alkali corrosion and protect paper. This study provides some theoretical guidance for the protection of paper cultural relics.

The aim of this study was to investigate an effective approach for improving the dissolving pulp properties for making specialty fiber. The caustic and enzymatic treatment of the properties of dissolving pulp was conducted by analyzing the macromolecular structure and chemical composition. The results showed that the enzymatic treatment was more effective on influencing the macromolecular properties, while the caustic treatment had more influence on structural changing, mainly cellulose crystal structure and crystallinity. Meanwhile, to maintain a higher purity and higher brightness, caustic treatment would be beneficial in comparison with enzymatic treatment. The performance of caustic treated sample was evaluated in regarding to chemical composition and acetylation reaction performance, using commercial pulp as reference. The competitive feature of treated sample suggested its potential in future application.

Due to discharge of hazardous organochlorine compounds and absorbable organic halogen compounds in the effluent, the pulp and paper industries are trying to alter the bleaching process to limit the use of chlorine compounds and comply with regulatory, environmental, and market demands. With progress in biotechnology, enzyme technologies can effectively pre-treat lignocellulosic biomass in the pulp and paper making process. Usually, these enzymatic processes reduce the environmental impact of traditional pulp and paper-making processes, lower the overall production cost, and enhance product quality. Microbial xylanases are the potential bio-bleaching candidate due to their renewable, mild operating, highly specific, and eco-friendly nature. Xylanase enhances the efficacy of the bleaching process by breaking the β-1, 4-glycosidic backbone of the re-precipitated xylan network and removing the trapped lignin from the pulp fibers. Xylanolytic action positively influences the kappa number, hexenuronic acid, chromophore compounds release, pulp crystallinity, morphology and many other attributes of pulp. The present review comprehensively highlights the microbial xylanolytic system, its mechanism, and its application in pulp bioleaching. With the recent development, the paper delineates the xylanase-aided bleaching effects on pulp, paper, and effluent attributes aimed to reduce bleaching chemical use, AOX formation, and energy use in the pulp refining process.

The main objective of this research is to evaluate the influence of coating based on cellulose micro/nanofibrils (CMF) and carboxylated styrene butadiene rubber (XSBR) on sack kraft paper, for possible use in packaging. Filmogenic solutions were applied manually as a coating on sack kraft paper. These solutions were prepared by suspensions of CMF 1.5 % w/v with the addition of different content of XSBR (0, 2, 10, and 20 % about the total mass of CMF). Uncoated sack kraft paper was used as control. Films were obtained by casting and characterized physically, morphologically, and mechanically. The results demonstrated that XSBR and CMF composite suspension showed good performance as a coating on sack kraft paper. The formation of homogeneous structures well distributed on paper can be observed on scanning electron microscope images. Coatings containing XSBR presented a smoother surface, less porosity and hydrophilicity, and a greater coalescence, with good properties of air resistance and water vapor permeability. However, regarding mechanical properties, there were no improvements in coated papers. Therefore, the present study contributed information on the development of more flexible and hydrophobic cellulosic papers for possible applications in the industrial packaging sector.

Carton board packages with different creases have been manufactured and loaded with point loads to see if there is a difference in point load behavior depending on crease. A carton board was creased in four different ways. The differences of the creases were judged according to appearance and residual moment. Three of the four creases showed divergent appearances. The residual moment was as expected lowest for the hardest creased sample and vice versa. The packages with the different creases were loaded with a point load. The registered force – displacement curves were analyzed according to stiffness and collapse load. No statistically significant difference could be seen in the collapse load of the package or in the stiffness measured, indicating that with a standard point load measurement it was hard to distinguish a difference in packaging behavior due to creasing. In future work it might be interesting to further study the average stiffness, since a trend of higher average stiffness for lower matrix channel depth exists in the measurements, however not statistically ensured. One possibility to discern possibly existing differences in the resistance of packaging to point load due to crease differences could be to study the interaction in more detail.

Waste newspaper causes contamination to the environment. Conversion of waste newspaper into activated carbon is a potential strategy due to its high carbon content. This paper aims to summarize recent advances in the production of activated carbons from waste newspaper and their applications in adsorption and wastewater treatment. The physicochemical properties from the use of different chemical activators with special emphasize on sodium salts to facilitate the adsorption of water pollutants were compared. The high BET surface and cost effectiveness allow the waste newspaper-based activated carbon as an economical alternative to be mass-produced for wastewater treatment.