Lignin has been extensively researched as a cathode active material in secondary batteries. In the present work, the energy storage potential of lignin naturally present in papers made of chemi-thermomechanical pulp (CTMP) is explored. More specifically, effects from CTMP fines on the electrochemical characteristics have been studied. Compared to pulp fibers, fines are higher in lignin content and have higher specific surface area. It was expected that this would be positive for the electrode performance; however, the result points to the opposite. The fines do not significantly contribute to a higher lignin specific capacity, and they deteriorate the cycling stability. Higher fines content was found to result in a higher oxidative activity as well as more abundant competing reactions. These competing reactions are believed to be linked to the cycle stability. Therefore, we hypothesize that the electrochemical stability of lignin can be better understood by studying differences between fines and fiber lignin. As the theoretical specific capacity of this material is about 20 times larger than obtained here, identification of the reasons for this capacity discrepancy is needed to realize the full potential of lignin-based paper batteries.

In the global pursuit for sustainable packaging solutions, usage of different paper raw material is one of the key components to fulfil the goal. Moulded fibre products allow usage of different fibre raw material, although for today, with some restrictions. For example, recycled fibre is of varying quality and can be a challenging material to use for thermoformed wet moulding applications. Further, CTMP strength potential should be further utilized for this application. In both cases, the stock preparation is crucial. The relationship between fibre type, stock preparation, processing and performance needs to be investigated to define how to best produce high-quality wet moulded fibre products using a specific fibre type. To be able to study this a laboratory equipment for manufacturing of high-quality wet moulded fibre products has been set up. Moreover, two test methods to evaluate properties important for trays have been developed; one to evaluate how much load the tray can take and one to evaluate how much the tray will warp during handling. Together with an optimised stock preparation for different fibre raw materials studies can be performed, which aim at increased usage of fibre qualities such as recycled fibre or CTMP for high-quality moulded fibre products. 

The objective in this work was to obtain a fine fraction of kraft pulp, with as high concentration as possible, in a pilot-scale fractionation with micro-perforated screen baskets. The influence of screen basket surface, hole size, feed concentration, pulp type and refining segment design was investigated. The results showed that a smooth screen basket surface improved the fractionation efficiency of the unrefined pulp compared to a profiled screen basket, despite a larger hole size. A significantly higher fine fraction concentration was obtained when using refined hardwood pulp compared to when using softwood pulp, which was explained with its lower average fibre length and narrower and thus more flexible fibre fragments. The pilot trials also showed that the screening process could be operated at feed concentrations similar to those directly after a refiner, 30-40 g/l. This was demonstrated in a process layout with partial recirculation where a refiner and a micro-perforated screen basket were operated in series in pilot scale. 

In this study, fines-enriched pulp (FE-pulp)-the fine fraction of highly-refined kraft pulp-was benchmarked against highly-refined kraft pulp (HRK-pulp) as a strength agent in eucalyptus chemithermomech. pulp (CTMP). Both the FE-pulp and the HRK-pulp were produced from unbleached softwood kraft pulp, and equal amounts of those strength agents were added to the original CTMP, as well as to washed CTMP, where most of the fines had been removed. The effects of the added strength agents were evaluated with laboratory handsheets. The FE-pulp proved to be twice as effective as HRK-pulp. Both HRK-pulp and FE-pulp increased the strength of the CTMP handsheets. The bulk of the handsheets decreased, however, as well as the drainability. The addition of 5% FE-pulp resulted in the same strength increase as an addition of 10% HRK-pulp, as well as the same decrease in bulk and CSF. For the handsheets of washed CTMP, the strengths were not measurable; the CTMP lost the sheet strength when the CTMP-fines content was reduced through washing. The reduced strength properties were compensated for by the addition of chem. pulp fines that proved to be an efficient strength agent. The addition of 5% FE-pulp restored the strength values, and at a higher bulk and higher drainability.

In this study, fines-enriched pulp (FE-pulp)-the fine fraction of highly-refined kraft pulp-was benchmarked against highly-refined kraft pulp (HRK-pulp) as a strength agent in eucalyptus chemithermomechanical pulp (CTMP). Both the FE-pulp and the HRK-pulp were produced from unbleached softwood kraft pulp, and equal amounts of those strength agents were added to the original CTMP, as well as to washed CTMP, where most of the fines had been removed. The effects of the added strength agents were evaluated with laboratory handsheets. The FE-pulp proved to be twice as effective as HRK-pulp. Both HRK-pulp and FE-pulp increased the strength of the CTMP handsheets. The bulk of the handsheets decreased, however, as well as the drainability. The addition of 5% FE-pulp resulted in the same strength increase as an addition of 10% HRK-pulp, as well as the same decrease in bulk and CSF. For the handsheets of washed CTMP, the strengths were not measurable; the CTMP lost the sheet strength when the CTMP-fines content was reduced through washing. The reduced strength properties were compensated for by the addition of chemical pulp fines that proved to be an efficient strength agent. The addition of 5% FE-pulp restored the strength values, and at a higher bulk and higher drainability. Application: In this study, we show how the strength of a CTMP sheet can be improved by adding fine material from kraft pulp.

The objective for this work was to investigate the possibility to use a pressure screen equipped with a micro-perforated screen basket to produce a fine fraction from bleached chemical pulp. Trials were performed with unrefined bleached chemical hardwood pulp, and with unrefined and refined bleached chemical softwood pulp. The effect of feed concentration, feed flow, and volumetric fine fraction flow was evaluated. The difference between the fine fraction (i. e. the particles passing the screen) and the feed was analysed by studying the fibre morphology. The results showed that high feed concentration was positive for both the fine fraction concentration and the separation efficiency. A higher fine fraction concentration was also obtained when using hardwood pulp, which was explained by the shorter fibre length. Refining of the pulp prior to the fractionation proved beneficial, as a larger share of the refined pulp passed the screen, resulting in a twice as high concentration of the fine fraction when compared to unrefined pulp.

This literature review focus on fibre length-based fractionation with screens to achieve a fine fraction, how fractionation results can be evaluated and on the influence of different screening parameters when using pressure screens. The design of the screen basket, and in particular the aperture size and shape, have a predominant effect on fractionation. Smaller aperture size leads to improved fractionation efficiency. Furthermore, it seems clear that screen plates with holes fractionate better than slotted, even when the slots are narrower than the hole diameter. Moreover, smooth screen plates are more efficient for fractionation, as contoured screen plates increase the fibre passage. For slotted screens the fibre passage ratio is affected by the fluid velocity through the aperture, while the fibre passage ratio for screen plates with small holes is independent of the fluid velocity. Microperforated screens, i.e. screens with holes with a diameter of less than 300 micrometre, are very efficient for fines fractionation in order to enrich the fines in the accept fraction.

A pilot scale study has been made of the concept of adding fibre-based strength agents (fines enriched (FE)-pulp or highly refined (HR)-pulp) in a board middle ply containing chemithermomechanical bleached pulp (CTMP) in order to increase bending stiffness of the board while maintaining Z-strength. It has been demonstrated that the bending stiffness of a sheet consisting of a top ply and a CTMP based middle ply could be improved by increasing the CTMP fraction and preventing Z-strength loss via addition of a fibre based strength agent. Compared with the reference pulp, both Z-strength and bulk increased for three of the compositions, namely 65% CTMP with 5% strength agent of either FE or HR type and 85% CTMP with 10% HR-pulp. FE-pulp was found to be more efficient than HR-pulp concerning bending stiffness improvement. While the highly-refined fibres of the strength agents had a negative effect on the drainage resistance and press dryness, an increased share of CTMP increased the press dryness linearly. FE-pulp and HR-pulp had the same impact on press dryness. Press solids could be improved by approximately 2% without significantly reducing the bulk by increasing press loads.

 For the first time in the Bioeconomy research program at RISE, corrugatedboard has an own research area. Research is building around the main driving forcesin the corrugated board value chain like e-commerce, improved box performance anddigital printing. The main weakness of corrugated board, its moisture sensitivity, isalso addressed.These main driving forces and weaknesses of corrugated board are mirrored in thethemes of this large research program area:Fibre sorption and deformation mechanismsFundamental knowledge on the mechanisms behind moisture sorption and deformation on fibre level is developed to increase moisture and creep resistance throughmodification of paper materials. State of the art methods for characterization ofthe fibre ultra- and nano-structure such as Fourier transform infra-red spectroscopy(FTIR), small angle X-ray scattering (SAXS), and wide angle X-ray scattering (WAXS)give new insights on mechanisms and clarify effects of moisture as well as chemicalmodifications.Papermaking for improved base sheetsConcepts that are explored are fibre-based strength additives produced with novelrefining techniques, and modified ZD-profiles in the sheet for better mechanical properties.Box mechanicsMechanical performance of structures such as corrugated board boxes can be predicted through physically based mathematical modelling by taking the behaviour ofthe constituent materials as well as the geometry into account. Appropriate materialmodels for the corrugated board are identified and finite element models for simulation of corrugated board packaging performance are developed.Tool for inkjet printability on corrugatedThere is a genuine need for improved inkjet printability on corrugated materials thanksto rapid development in e-commerce as well as digitalization along the corrugatedvalue chain. Effective measurement methods and knowledge around ink-substrateinteractions are developed to enable board producers and converters to have effective product development and predictable printability on not only liners but also oncorrugated materials.

The objective of this pilot scale trial, was to evaluate fines-enriched pulp (FE-pulp) as a strength agent in amiddle ply of a board product.A typical CTMP-based middle ply was produced on the FEX pilot paper machine. The stock consisted of CTMP,refined hardwood and softwood pulp, and filler. FE-pulp as strength agent was compared with glue pulp, ahighly refined chemical pulp. FEX sheets and hand sheets made of pulp mixtures were evaluated. Also, thedewatering and pressing conditions on the paper machine were compared.The results confirmed the results of earlier experiments with handsheets; FE-pulp used as strength agent showedto be twice as efficient as glue pulp regarding strength properties without impairing the bulk. Further, thedewatering conditions and press dryness's on the paper machine was comparable at these additions. Thus, allthese results imply that addition of FE-pulp can replace the double amount of glue pulp as a strength agent.