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Nucleic acid amplification testing (NAAT) is the gold standard for infectious disease diagnostics. Currently NAATs are mainly limited to centralized laboratories, while paper-based antigen tests are used for rapid home-based diagnostics. DNA extraction, the initial sample preparation step in NAATs, remains a bottleneck that hinders its development toward home-based kits. This step requires the use of compounds detrimental to the enzymes in downstream DNA amplification. Here, this work overcomes this bottleneck by immobilizing the enzyme achromopeptidase (ACP) on nitrocellulose, to both store and enable the separation of the enzymes from the other steps. This work provides proof-of-concept that immobilized ACP is effective at lysis and release of amplifiable DNA from gram-positive Staphylococcus epidermidis and enables the use of the lysate directly for DNA amplification, without the need for heat deactivation of the enzyme. This sample preparation method requires only incubation at 37 °C and mild agitation, which allows to implement it with fully disposable and affordable equipment. Consequently, this work enables to combine the paper-based DNA extraction method with the isothermal recombinase polymerase amplification (RPA) followed by lateral flow detection to demonstrate a sample-to-answer NAAT packaged as an instrument free self-test kit expanding the capabilities of home-testing beyond antigen tests., QC 20230614

Ultrasonication was used as a mean toincorporate glycerolor urea, yielding paper films with a ductility of up to 35%. Fiber-based materials are attractive sustainable alternativestofossil-based plastics, however, the lack of ductility (i.e., brittleness)limits their applicability in complex shapes as are often utilizedfor plastics. In this study, we hypothesize that it is possible toenhance the ductility of a cellulose-rich material by the incorporationof low molecular weight plasticizers (glycerol, urea, citric acid,and tannic acid). However, no significant effects could be observedafter swelling in the presence of plasticizers. To enhance any potentialeffect, it was decided to employ ultrasonication to mechanically disintegratethe fiber and aid the sorption of plasticizer prior to formation ofsheets from the treated fibers. Glycerol or urea in combination withultrasonication resulted in both internal and external fibrillationof the fibers, and it could be observed that the resulting fines createa film at the surface of the fibers in the formed sheets. Tensiletesting shows that this gives rise to a 100% increase in ductilitycompared to sheets from untreated fibers. The use of citric or tannicacid has the opposite effect, reducing ductility to a third of thatof the reference sheet. This is suggested to be due to the formationof covalent cross-links in the treated fibers, which also leads todifferent internal and external fibrillation mechanisms, as observedby scanning electron microscopy. The exceptionally high improvementof the strain-at-break for sheets from the glycerol- and urea-treatedfibers suggests that low molecular weight plasticizers affect theinternal properties of the fiber wall as well as the interactionsbetween the fine material forming in-between the fibers. The findingsfrom the current study suggest that the proposed approach to obtainductile cellulose-rich materials holds promise for the future, butit is also clear that more in-depth research is req, QC 20230630

Using biobased polyelectrolytes to emulsify natural fatty molecules is one possible key technology to create sustainable materials. The emulsions can be used in papermaking instead of synthetic hydrophobizing agents or in nonwoven manufacturing to create strong, hydrophobic textile-like materials. This article investigates a novel emulsification system based on a polyelectrolyte complex between chitosan dissolved in citric acid and carboxymethyl cellulose together with sunflower (Helianthus annuus) oil. Viscose nonwoven treated with the emulsion had a contact angle of over 120°. Tensile tests showed that the produced paper and nonwoven materials achieved high dry and, especially, high wet strength. Infrared spectroscopy illuminated the impact of heat curing the binder, and electron microscopy showed that the oil droplets from the emulsion were spread across the fibre surface. The results from this study enable sustainable nonwovens to be applied in areas where high dry and wet strength and water repellence are required; this includes outdoor applications, including agricultural mulch films, where nonwoven is used frequently and a sustainable approach is urgently needed to reduce the accumulation of plastics in the environment., QC 20230626

The use of paper dry strength additives is oneof the methods for producing packaging boards with alower grammage while maintaining mechanical properties.In the present work, papers were formed using dissolvinggrade kraft fibres, kraft fibres and carboxymethylatedcellulose (CMC) modified kraft fibres (C-kraft fibres),with either cationic starch (CS), anionic polyacrylamide(APAM) or anionic polyelectrolyte complexes (PECs). Fibresand sheets were characterized to evaluate how the saturationadsorption of the different strength additives influencesthe properties of the treated fibres and the finalhandsheets. The tensile index of papers made from C-kraftfibres was the highest due to the highest adsorption capacityof strength additives. Moreover, the strength additivesincreased the tensile index by 33–84 %, while z-directional tensile strength was increased dramatically by 46–139 %.Bending stiffness was improved by 2.6–25 %, and the combination of CS and APAM or PECs resulted in a significantimprovement in bending stiffness compared to the addition of CS alone. Importantly, the strength improvement did not sacrifice the density significantly. In summary, theknowledge gained from the current study expands the understanding of strength additives and their relationship with fibres of different surface charge and the overall paper properties., QC 20221227

The use of paper dry strength additives is oneof the methods for producing packaging boards with alower grammage while maintaining mechanical properties.In the present work, papers were formed using dissolvinggrade kraft fibres, kraft fibres and carboxymethylatedcellulose (CMC) modified kraft fibres (C-kraft fibres),with either cationic starch (CS), anionic polyacrylamide(APAM) or anionic polyelectrolyte complexes (PECs). Fibresand sheets were characterized to evaluate how the saturationadsorption of the different strength additives influencesthe properties of the treated fibres and the finalhandsheets. The tensile index of papers made from C-kraftfibres was the highest due to the highest adsorption capacityof strength additives. Moreover, the strength additivesincreased the tensile index by 33–84 %, while z-directional tensile strength was increased dramatically by 46–139 %.Bending stiffness was improved by 2.6–25 %, and the combination of CS and APAM or PECs resulted in a significantimprovement in bending stiffness compared to the addition of CS alone. Importantly, the strength improvement did not sacrifice the density significantly. In summary, theknowledge gained from the current study expands the understanding of strength additives and their relationship with fibres of different surface charge and the overall paper properties., QC 20221227

Light-weight paper products that contain less fibres, but with a maintained bulk and improved strength properties, are highly desirable due to the low cost of raw materials and improved logistics of packaged goods. In this respect, the adsorption capacity of dry strength additives onto fibres, which is affected by the surface charge of said fibres, is very important for the development of these mechanically robust paper products. The influence of the surface charge on the adsorption of strength additives was investigated for, dissolving grade fibres, kraft fibres and kraft fibres modified with carboxymethyl cellulose (CMC) with different surface charge densities, but the same fibre dimensions. The strength additives investigated were cationic starch (CS), anionic polyacrylamide (APAM) and polyelectrolyte complexes (PECs), containing CS and APAM. A linear relationship was found between the surface charge of the fibres and the saturated adsorbed amount of CS. However, when either APAM or PECs adsorbed as secondary layers onto the CS, no correlation between cellulose charge and the saturation adsorption could be observed. The adsorption of APAM was dramatically affected by the pre-adsorbed amount of CS, whereas PECs were less influenced. Moreover, the additives improved the tensile strength (60%) and strain at break (> 100%) of handsheets formed with the kraft fibres and adsorbed APAM. It was also found that CS/APAM increased the sheet density while CS/PECs lowered it. In conclusion, the gained fundamental understanding of these adsorption of additives is of significant importance to facilitate the industrial development of sustainable low-cost high-end packaging products. Graphical abstract: [Figure not available: see fulltext.], QC 20221027

The use of paper dry strength additives is oneof the methods for producing packaging boards with alower grammage while maintaining mechanical properties.In the present work, papers were formed using dissolvinggrade kraft fibres, kraft fibres and carboxymethylatedcellulose (CMC) modified kraft fibres (C-kraft fibres),with either cationic starch (CS), anionic polyacrylamide(APAM) or anionic polyelectrolyte complexes (PECs). Fibresand sheets were characterized to evaluate how the saturationadsorption of the different strength additives influencesthe properties of the treated fibres and the finalhandsheets. The tensile index of papers made from C-kraftfibres was the highest due to the highest adsorption capacityof strength additives. Moreover, the strength additivesincreased the tensile index by 33–84 %, while z-directional tensile strength was increased dramatically by 46–139 %.Bending stiffness was improved by 2.6–25 %, and the combination of CS and APAM or PECs resulted in a significantimprovement in bending stiffness compared to the addition of CS alone. Importantly, the strength improvement did not sacrifice the density significantly. In summary, theknowledge gained from the current study expands the understanding of strength additives and their relationship with fibres of different surface charge and the overall paper properties., QC 20221227

The use of paper dry strength additives is oneof the methods for producing packaging boards with alower grammage while maintaining mechanical properties.In the present work, papers were formed using dissolvinggrade kraft fibres, kraft fibres and carboxymethylatedcellulose (CMC) modified kraft fibres (C-kraft fibres),with either cationic starch (CS), anionic polyacrylamide(APAM) or anionic polyelectrolyte complexes (PECs). Fibresand sheets were characterized to evaluate how the saturationadsorption of the different strength additives influencesthe properties of the treated fibres and the finalhandsheets. The tensile index of papers made from C-kraftfibres was the highest due to the highest adsorption capacityof strength additives. Moreover, the strength additivesincreased the tensile index by 33–84 %, while z-directional tensile strength was increased dramatically by 46–139 %.Bending stiffness was improved by 2.6–25 %, and the combination of CS and APAM or PECs resulted in a significantimprovement in bending stiffness compared to the addition of CS alone. Importantly, the strength improvement did not sacrifice the density significantly. In summary, theknowledge gained from the current study expands the understanding of strength additives and their relationship with fibres of different surface charge and the overall paper properties., QC 20221227

The use of paper dry strength additives is oneof the methods for producing packaging boards with alower grammage while maintaining mechanical properties.In the present work, papers were formed using dissolvinggrade kraft fibres, kraft fibres and carboxymethylatedcellulose (CMC) modified kraft fibres (C-kraft fibres),with either cationic starch (CS), anionic polyacrylamide(APAM) or anionic polyelectrolyte complexes (PECs). Fibresand sheets were characterized to evaluate how the saturationadsorption of the different strength additives influencesthe properties of the treated fibres and the finalhandsheets. The tensile index of papers made from C-kraftfibres was the highest due to the highest adsorption capacityof strength additives. Moreover, the strength additivesincreased the tensile index by 33–84 %, while z-directional tensile strength was increased dramatically by 46–139 %.Bending stiffness was improved by 2.6–25 %, and the combination of CS and APAM or PECs resulted in a significantimprovement in bending stiffness compared to the addition of CS alone. Importantly, the strength improvement did not sacrifice the density significantly. In summary, theknowledge gained from the current study expands the understanding of strength additives and their relationship with fibres of different surface charge and the overall paper properties., QC 20221227

QC 20221114

Bio-based monomers represent the future market for polymer chemistry, since the political economics of different states promote green ventures toward more sustainable materials and processes. Industrial pulp and paper processing represent a large market that could advance the use of by-products to avoid waste production and reduce pollution. Lignin represents the most available side product that can be used to produce a bio-based monomer. This review is concentrated on the possibility of using bio-based monomer derivates from pulp and the paper industry for UV-curing processing. UV-curing represents the new frontier for thermoset production, allowing a fast reaction cure, less energy demand, and the elimination of solvent. The growing demand for new monomers increases research in the environmental field to substitute for petroleum-based products. This review provides an overview of the main monomers and relative families of compounds derived from industrial processes that are suitable for UV-curing. Particular focus is given to the developments reached in the last few years concerning lignin, rosin and terpenes and the related possible applications of these in UV-curing chemistry., QC 20220302

Paper grade pulp production across the globe is dominated by the kraft process using different lignocellulosic raw materials. Delignification is achieved around 90% using different chemical treatments. A bottleneck for complete delignification is the presence of residual covalent bonds that prevail between lignin and carbohydrate even after severe chemical pulping and oxygen delignification steps. Different covalent bonds are present in native wood that sustain drastic pulping conditions. In this study, 100% birch wood was used for producing paper grade pulp, and the lignin carbohydrate bonds were analyzed at different stages of the kraft cook. The lignin carbohydrate bonds that were responsible for residual lignin retention in unbleached pulp were compared and analyzed with the original lignin-carbohydrate complex (LCC) bonds in native birch wood. It was shown that lignin remaining after pulping and oxygen delignification was mainly bound to xylan, whereas the lignin bound to glucomannan was for the most part degraded., QC 20201023

The potential to modify pulp and paper properties by oxygen delignification was assessed by looking beyond the ordinary purpose of oxygen delignification. Pulps with the same kappa number were obtained by both pulping and the combination of pulping and oxygen delignification, and the mechanical and chemical properties were compared. The oxidation of pulp components leads to an increase in carboxylic acid groups in the fibers, resulting in a large influence on fiber swelling, seen as an increase in the water retention value and fiber saturation point. The introduction of charged groups appears to replace some of the morphological changes caused by refining and enhance the strength of fiber-fiber joints, generating pulps with better refinability and higher tensile strength. Oxygen delignification was able to improve the tensile index with 6% at the same sheet density and less refining energy, when the amount of total fiber charges was higher than 140 mu ekv/g., QC 20200727

Cellulosic paper products based on sustainable resources are of interest as a replacement for petroleum-based plastics, for example, in packaging applications. Improvements are desired for mechanical performance, recyclability, and possibilities to shape fiber networks into complex geometries. Commercial bleached wood fibers from the kraft process have insufficient mechanical properties for many applications, even with beating and additives. In addition, mechanical properties of paper structures are significantly reduced after recycling. Here, recycling and 3D shaping performance of holocellulose fibers are compared with kraft fibers and investigated in the context of wood fiber tailoring for eco-friendly materials. Holocellulose fibers from wood are prepared by mild peracetic acid delignification for well-preserved nanostructures and hemicellulose content (28 wt %). Paper structures of about 50% porosity are prepared from both types of fibers by vacuum filtration and drying. Mechanical tensile tests are performed, and fracture surfaces are investigated. The effects of recycling on the fiber structure (chemical composition, morphology, and crystallite size in fibers) and mechanical paper properties are reported. 3D-shaping performance is studied using compression molding with a double-curved mold. Holocellulose paper structures showed much better mechanical properties than kraft fiber paper (Young's modulus 10 GPa, ultimate tensile strength 100 MPa), as well as better recycling performance (only 26% decrease in strength after 5 cycles) and 3D formability. The well-preserved cellulose and hemicellulose components are important, as well as the homogeneity of the fiber cell wall nanostructure. This preserves the intrinsic mechanical properties of fibers, reduces hornification effects, and provides strong interfiber adhesion. Furthermore, the water-soluble hemicelluloses present at the cellulose-cellulose interface are able to facilitate recycling and 3D forming., QC 20200217

Percolation of contaminated water through paper sheets containing silver nanoparticles is a promising way to provide emergency drinking water. The silver nanoparticles are deposited by the in situ reduction of silver nitrate on the cellulose fibers of an absorbent blotting paper sheet. Sodium borohydride has been used as the reductant but is toxic and expensive. Glucose is a benign alternative but is much less reactive. In this note, we demonstrate an improved way to produce silver nanoparticles in paper sheets by adding sodium hydroxide to the glucose reductant. The silver content of the sheets, measured by diffuse reflectance spectroscopy, was around 2-3 mg of silver per gram of dry paper. This was sufficient to reduce the concentration of a model Escherichia coli suspension after percolation through the sheet., QC 20181012

To expand the use of renewable materials, paper products with superior mechanical and optical properties are needed. Although beating, bleaching, and additives are known to improve industrially produced Kraft pulp papers, properties are limited by the quality of the fibers. While the use of nanocellulose has been shown to significantly increase paper properties, the current cost associated with their production has limited their industrial relevance. Here, using a simple mild peracetic acid (PAA) delignification process on spruce, we produce hemicellulose-rich holocellulose fibers (28.8 wt %) with high intrinsic strength (1200 MPa for fibers with microfibrillar angle smaller than 10 degrees). We show that PAA treatment causes less cellulose/hemicellulose degradation and better preserves cellulose nanostructure in comparison to conventional Kraft pulping. High-density holocellulose papers with superior mechanical properties (Young's modulus of 18 GPa and ultimate strength of 195 MPa) are manufactured using a water-based hot-pressing process, without the use of beating or additives. We propose that the preserved hemicelluloses act as "glue" in the interfiber region, improving both mechanical and optical properties of papers. Holocellulose fibers may be affordable and applicable candidates for making special paper/composites where high mechanical performance and/or optical transmittance are of interest., QC 20180803

Paper is emerging as a promising flexible, high surface-area substrate for various new applications such as printed electronics, energy storage, and paper-based diagnostics. Many applications, however, require paper that reaches metallic conductivity levels, ideally at low cost. Here, an aqueous electroless copper-plating method is presented, which forms a conducting thin film of fused copper nanoparticles on the surface of the cellulose fibers. This paper can be used as a current collector for anodes of lithium-ion batteries. Owing to the porous structure and the large surface area of cellulose fibers, the copper-plated paper-based half-cell of the lithium-ion battery exhibits excellent rate performance and cycling stability, and even outperforms commercially available planar copper foil-based anode at ultra-high charge/discharge rates of 100 C and 200 C. This mechanically robust metallic-paper composite has promising applications as the current collector for light-weight, flexible, and foldable paper-based 3D Li-ion battery anodes., QC 20190625

Filtration is a common way to obtain pure drinking water by removing particles and microorganisms based on size exclusion. Cellulose-based filters are affordable and biobased option for the removal of particles but bacteria are usually too small to be removed by size exclusion alone. In this article, the surfaces of cellulose fibres in two types of commercial paper filters have been given a positive net charge to trap bacteria through electrostatic interactions without releasing any biocides. The fibres were modified with the cationic polyelectrolyte polyvinylamine polymer in single layers (1 L) or in multilayers together with the anionic polyelectrolyte polyacrylic acid (3 L or 5 L) using a water-based process at room temperature. Filtration tests show that all filters, using both types of filter papers and a number of layers, can physically remove more than 99.9% of E. coli from water and that the 3 L modified filters can remove more than 97% of cultivatable bacteria from natural water samples. The bacterial reduction increased with increasing number of filter sheets used for the filtration and the majority of the bacteria were trapped in the top sheets of the filter. The results show the potential for creating water purification filters from bio-based everyday consumable products with a simple modification process. The filters could be used in the future for point-of-use water purification that may be able to save lives without releasing bactericides., QC 20181112

Filtration is a common way to obtain pure drinking water by removing particles and microorganisms based on size exclusion. Cellulose-based filters are affordable and biobased option for the removal of particles but bacteria are usually too small to be removed by size exclusion alone. In this article, the surfaces of cellulose fibres in two types of commercial paper filters have been given a positive net charge to trap bacteria through electrostatic interactions without releasing any biocides. The fibres were modified with the cationic polyelectrolyte polyvinylamine polymer in single layers (1 L) or in multilayers together with the anionic polyelectrolyte polyacrylic acid (3 L or 5 L) using a water-based process at room temperature. Filtration tests show that all filters, using both types of filter papers and a number of layers, can physically remove more than 99.9% of E. coli from water and that the 3 L modified filters can remove more than 97% of cultivatable bacteria from natural water samples. The bacterial reduction increased with increasing number of filter sheets used for the filtration and the majority of the bacteria were trapped in the top sheets of the filter. The results show the potential for creating water purification filters from bio-based everyday consumable products with a simple modification process. The filters could be used in the future for point-of-use water purification that may be able to save lives without releasing bactericides., QC 20181112

Filtration is a common way to obtain pure drinking water by removing particles and microorganisms based on size exclusion. Cellulose-based filters are affordable and biobased option for the removal of particles but bacteria are usually too small to be removed by size exclusion alone. In this article, the surfaces of cellulose fibres in two types of commercial paper filters have been given a positive net charge to trap bacteria through electrostatic interactions without releasing any biocides. The fibres were modified with the cationic polyelectrolyte polyvinylamine polymer in single layers (1 L) or in multilayers together with the anionic polyelectrolyte polyacrylic acid (3 L or 5 L) using a water-based process at room temperature. Filtration tests show that all filters, using both types of filter papers and a number of layers, can physically remove more than 99.9% of E. coli from water and that the 3 L modified filters can remove more than 97% of cultivatable bacteria from natural water samples. The bacterial reduction increased with increasing number of filter sheets used for the filtration and the majority of the bacteria were trapped in the top sheets of the filter. The results show the potential for creating water purification filters from bio-based everyday consumable products with a simple modification process. The filters could be used in the future for point-of-use water purification that may be able to save lives without releasing bactericides., QC 20181112

Filtration is a common way to obtain pure drinking water by removing particles and microorganisms based on size exclusion. Cellulose-based filters are affordable and biobased option for the removal of particles but bacteria are usually too small to be removed by size exclusion alone. In this article, the surfaces of cellulose fibres in two types of commercial paper filters have been given a positive net charge to trap bacteria through electrostatic interactions without releasing any biocides. The fibres were modified with the cationic polyelectrolyte polyvinylamine polymer in single layers (1 L) or in multilayers together with the anionic polyelectrolyte polyacrylic acid (3 L or 5 L) using a water-based process at room temperature. Filtration tests show that all filters, using both types of filter papers and a number of layers, can physically remove more than 99.9% of E. coli from water and that the 3 L modified filters can remove more than 97% of cultivatable bacteria from natural water samples. The bacterial reduction increased with increasing number of filter sheets used for the filtration and the majority of the bacteria were trapped in the top sheets of the filter. The results show the potential for creating water purification filters from bio-based everyday consumable products with a simple modification process. The filters could be used in the future for point-of-use water purification that may be able to save lives without releasing bactericides., QC 20181112

Filtration is a common way to obtain pure drinking water by removing particles and microorganisms based on size exclusion. Cellulose-based filters are affordable and biobased option for the removal of particles but bacteria are usually too small to be removed by size exclusion alone. In this article, the surfaces of cellulose fibres in two types of commercial paper filters have been given a positive net charge to trap bacteria through electrostatic interactions without releasing any biocides. The fibres were modified with the cationic polyelectrolyte polyvinylamine polymer in single layers (1 L) or in multilayers together with the anionic polyelectrolyte polyacrylic acid (3 L or 5 L) using a water-based process at room temperature. Filtration tests show that all filters, using both types of filter papers and a number of layers, can physically remove more than 99.9% of E. coli from water and that the 3 L modified filters can remove more than 97% of cultivatable bacteria from natural water samples. The bacterial reduction increased with increasing number of filter sheets used for the filtration and the majority of the bacteria were trapped in the top sheets of the filter. The results show the potential for creating water purification filters from bio-based everyday consumable products with a simple modification process. The filters could be used in the future for point-of-use water purification that may be able to save lives without releasing bactericides., QC 20181112

Chemically modified cellulose micro- and nanofibrils were successfully used as paper strength additives. Three different kinds of cellulose nanofibrils (CNFs) were studied: carboxymethylated CNFs, periodate-oxidised carboxymethylated CNFs and dopamine-grafted carboxymethylated CNFs, all prepared from bleached chemical fibres of dissolving grade, and one microfibrillated cellulose from unbleached kraft fibres. In addition to mechanical characterization of the final paper sheets the fibril retention, sheet density and sheet morphology were also studied as a function of addition of the four different cellulose fibrils. In general, the cellulose fibrils, when used as additives, significantly increased the tensile strength, Young’s modulus and strain-at-break of the paper sheets. The effects of the different fibrils on these properties were compared and evaluated and used to analyse the underlying mechanisms behind the strengthening effect. The strength-enhancing effect was most pronounced for the periodate-oxidised CNFs when they were added together with polyvinyl amine (PVAm) or poly(dimethyldiallylammonium chloride) (pDADMAC). The addition of periodate-oxidised CNFs, with pDADMAC as retention aid, resulted in a 37% increase in tensile strength at a 2 wt% addition and an 89% increase at a 15 wt% addition (from 67 to 92 and 125 kNm/kg, respectively) compared to a reference with only pDADMAC. Wet-strong sheets with a wet tensile index of 30 kNm/kg were also obtained when periodate-oxidised CNFs and PVAm were combined. This significant increase in wet strength is suggested to be the result of a formation of cross-links between the aldehyde groups, introduced by the periodate oxidation, and hydroxyl groups on the lignocellulosic fibres and the primary amines of PVAm. Even though less significant, there was also an increase in wet tensile strength when pDADMAC was used together with periodate-oxidised fibrils which shows that the aldehyde groups are able to increase the wet, QC 20180117

The nematic structuring of cellulose nanofibers (CNFs) is proposed as a nanostructural engineering tool for exploiting the potential of CNFs in conceptually new "transparent papers". The nematic-structured CNF papers exhibit superior mechanical properties, optical transparency, gas-barrier properties, heat transfer properties and electrical resistivity, compared with conventional randomly-structured CNF papers., Non-duplicate with ISI: 000435537702500QC 20180227

The layer-by-layer (LbL) technology was used to adsorb polyelectrolyte multilayers consisting of cationic polyethylenimine (PEI) and anionic sodium hexametaphosphate (SHMP) onto cellulose fibers in order to enhance the flame-retardancy and tensile strength of paper sheets made from these fibers. The fundamental effect of PEI molecular mass on the build-up of the multilayer film was investigated using model cellulose surfaces and a quartz crystal microbalance technique. The adsorption of a low (LMw) and a high molecular weight (HMw) PEI onto cellulose fibers and carboxymethylated (CM) cellulose fibers was investigated using polyelectrolyte titration. The fibers were consecutively treated with PEI and SHMP to deposit 3.5 bilayers (BL) on the fiber surfaces, and the treated fibers were then used to prepare sheets. In addition, a wet-strength paper sheet was prepared and treated with the same LbL coatings. Thermal gravimetric analysis of LbL-treated fibers showed that the onset temperature for cellulose degradation was lowered and that the amount of residue at 800 °C increased. A horizontal flame test and a vertical flame test were used to evaluate the combustion behavior of the paper sheets. Papers prepared from both cellulose fibers and CM-cellulose fibers treated with HMw-PEI/SHMP LbL-combination self-extinguished in a horizontal configuration despite the rather low amounts of adsorbed polymer which form very thin films (wet thickness of ca. 17 nm). The tensile properties of handsheets showed that 3.5 BL of HMw-PEI and SHMP increased the stress at break by 100% compared to sheets prepared from untreated cellulose fibers., QC 20180411

Surface discharge behavior of modified oil-impregnated paper (OIP) with nanoparticles (NPs), has been investigated under AC voltage with superimposed impulses. Surface Partial Discharges (PD) can develop at an oil-paper interface and lead to its degradation. Modified paper, made from fibers with adsorbed nanoparticles, can affect the partial discharge behavior of a paper in combination with oil at the interface between oil and fibers. Papers with two different concentrations (2 wt% and 6 wt%) of silica (SiO2), and paper with silanized zinc oxide (ZnO) nanoparticles (1 wt%) have been studied. Papers with SiO2 NPs showed lower impulse-induced surface PD activity. However, thorough purification during the production of SiO2 filled papers was necessary to achieve a good performance. With less purification, paper with 2 wt% of SiO2 did not show such significant improvements. Paper with 6 wt% of SiO2 NPs showed a large number of AC surface PDs, but low influence of impulse voltage on subsequent PD. Papers containing 1 wt% of silanized ZnO showed reduced relative permittivity, but no significant difference in surface PD behavior. The effect of high lignin content in Kraft paper has also been studied. Paper with higher lignin content showed better surface PD characteristics under the impulse. Paper with low concentrations of pure SiO2 NPs, and paper with high lignin content thus appear good candidates for further studies to improve the surface PD behavior of OIP., QC 201708010

QC 20201230

Nanostructured materials are difficult to prepare rapidly and at large scale. Melt-processed polymer-clay nanocomposites are an exception, but the clay content is typically below 5 wt%. An approach for manufacturing of microfibrillated cellulose (MFC)/kaolinite nanocomposites is here demonstrated in pilot-scale by continuous production of hybrid nanopaper structures with thickness of around 100 μm. The colloidal nature of MFC suspensions disintegrated from chemical wood fiber pulp offers the possibility to add kaolinite clay platelet particles of nanoscale thickness. For initial lab scale optimization purposes, nanocomposite processing (dewatering, small particle retention etc) and characterization (mechanical properties, density etc) were investigated using a sheet former (Rapid Köthen). This was followed by a continuous fabrication of composite paper structures using a pilot-scale web former. Nanocomposite morphology was assessed by scanning electron microscopy (SEM). Mechanical properties were measured in uniaxial tension. The fire retardancy was evaluated by cone calorimetry. Inorganic hybrid composites with high content of in-plane oriented nanocellulose, nanoclay and wood fibers were successfully produced at pilot scale. Potential applications include fire retardant paperboard for semi structural applications., QC 20180530

This work presents an experimental study ofsecond mode positive streamers propagating along mineral oilpaperinterfaces. A point-plane arrangement immersed inmineral oil with the paper inclined 60 degrees to the planeelectrode is used to create the liquid-solid interface. Kraft paperand a kraft fibril paper, made from cellulosic micro and nanofibrils, with higher density and lower surface roughness are usedas the solid materials. High speed shadowgraphy and chargerecordings are used to compare the propagation of second modepositive streamers along the mineral oil-kraft paper and mineraloil-kraft fibril paper. Streamers creeping along the mineral oilkraftpaper interface propagate mainly into the liquid, with oneor two main filaments. In comparison, the streamers propagatingalong the kraft fibril paper show a strong reduction of thebranching; these streamers consist of a single filament thatpropagates exactly on the solid surface. Streamers along the kraftfibril paper also have longer propagation time than for the casewith kraft paper. Mutual electrostatic shielding betweenfilaments is observed for the streamers creeping on the kraftpaper. An electrostatic analysis of the influence of permittivity,density and surface roughness of the solid in the electricalproperties of the streamer filaments is also performed., QC 20170901

This work presents an experimental study ofsecond mode positive streamers propagating along mineral oilpaperinterfaces. A point-plane arrangement immersed inmineral oil with the paper inclined 60 degrees to the planeelectrode is used to create the liquid-solid interface. Kraft paperand a kraft fibril paper, made from cellulosic micro and nanofibrils, with higher density and lower surface roughness are usedas the solid materials. High speed shadowgraphy and chargerecordings are used to compare the propagation of second modepositive streamers along the mineral oil-kraft paper and mineraloil-kraft fibril paper. Streamers creeping along the mineral oilkraftpaper interface propagate mainly into the liquid, with oneor two main filaments. In comparison, the streamers propagatingalong the kraft fibril paper show a strong reduction of thebranching; these streamers consist of a single filament thatpropagates exactly on the solid surface. Streamers along the kraftfibril paper also have longer propagation time than for the casewith kraft paper. Mutual electrostatic shielding betweenfilaments is observed for the streamers creeping on the kraftpaper. An electrostatic analysis of the influence of permittivity,density and surface roughness of the solid in the electricalproperties of the streamer filaments is also performed., QC 20170901

This work presents an experimental study ofsecond mode positive streamers propagating along mineral oilpaperinterfaces. A point-plane arrangement immersed inmineral oil with the paper inclined 60 degrees to the planeelectrode is used to create the liquid-solid interface. Kraft paperand a kraft fibril paper, made from cellulosic micro and nanofibrils, with higher density and lower surface roughness are usedas the solid materials. High speed shadowgraphy and chargerecordings are used to compare the propagation of second modepositive streamers along the mineral oil-kraft paper and mineraloil-kraft fibril paper. Streamers creeping along the mineral oilkraftpaper interface propagate mainly into the liquid, with oneor two main filaments. In comparison, the streamers propagatingalong the kraft fibril paper show a strong reduction of thebranching; these streamers consist of a single filament thatpropagates exactly on the solid surface. Streamers along the kraftfibril paper also have longer propagation time than for the casewith kraft paper. Mutual electrostatic shielding betweenfilaments is observed for the streamers creeping on the kraftpaper. An electrostatic analysis of the influence of permittivity,density and surface roughness of the solid in the electricalproperties of the streamer filaments is also performed., QC 20170901

Cellulose nanopaper consists of a dense fibrous self-binding network composed of cellulose nanofibres connected by physical entanglements, hydrogen bonding, etc. Compared with conventional printing paper, cellulose nanopaper has higher strength and modulus because of stronger fibres and inter-fibre bonding. The aim of this paper is to investigate the fracture properties of cellulose nanopaper using double edge notch tensile tests on samples with different notch lengths. It was found that strength is insensitive to notch length. A cohesive zone model was used to describe the fracture behaviour of notched cellulose nanopaper. Fracture energy was extracted from the cohesive zone model and divided into an energy component consumed by damage in the material and a component related to pull-out or bridging of nanofibres between crack surfaces which was not facilitated due to the limited fibre lengths for the case of nanopapers. For comparison, printing paper which has longer fibres than nanopaper was tested and modelled to demonstrate the importance of fibre length. Buckypaper, a fibrous network made of carbon nanotubes connected through van der Waals forces and physical entanglements, was also investigated to elaborate on the influence of inter-fibre connections., QC 20170706

This work presents an experimental study ofsecond mode positive streamers propagating along mineral oilpaperinterfaces. A point-plane arrangement immersed inmineral oil with the paper inclined 60 degrees to the planeelectrode is used to create the liquid-solid interface. Kraft paperand a kraft fibril paper, made from cellulosic micro and nanofibrils, with higher density and lower surface roughness are usedas the solid materials. High speed shadowgraphy and chargerecordings are used to compare the propagation of second modepositive streamers along the mineral oil-kraft paper and mineraloil-kraft fibril paper. Streamers creeping along the mineral oilkraftpaper interface propagate mainly into the liquid, with oneor two main filaments. In comparison, the streamers propagatingalong the kraft fibril paper show a strong reduction of thebranching; these streamers consist of a single filament thatpropagates exactly on the solid surface. Streamers along the kraftfibril paper also have longer propagation time than for the casewith kraft paper. Mutual electrostatic shielding betweenfilaments is observed for the streamers creeping on the kraftpaper. An electrostatic analysis of the influence of permittivity,density and surface roughness of the solid in the electricalproperties of the streamer filaments is also performed., QC 20170901

This work presents an experimental study ofsecond mode positive streamers propagating along mineral oilpaperinterfaces. A point-plane arrangement immersed inmineral oil with the paper inclined 60 degrees to the planeelectrode is used to create the liquid-solid interface. Kraft paperand a kraft fibril paper, made from cellulosic micro and nanofibrils, with higher density and lower surface roughness are usedas the solid materials. High speed shadowgraphy and chargerecordings are used to compare the propagation of second modepositive streamers along the mineral oil-kraft paper and mineraloil-kraft fibril paper. Streamers creeping along the mineral oilkraftpaper interface propagate mainly into the liquid, with oneor two main filaments. In comparison, the streamers propagatingalong the kraft fibril paper show a strong reduction of thebranching; these streamers consist of a single filament thatpropagates exactly on the solid surface. Streamers along the kraftfibril paper also have longer propagation time than for the casewith kraft paper. Mutual electrostatic shielding betweenfilaments is observed for the streamers creeping on the kraftpaper. An electrostatic analysis of the influence of permittivity,density and surface roughness of the solid in the electricalproperties of the streamer filaments is also performed., QC 20170901

Effective high-yield recycling of waste paper to well-defined future platform chemicals and carbon nanospheres was demonstrated. The developed process utilized the exceptional combined effect of microwave irradiation and dilute acid catalyst to hydrothermally degrade cellulose in waste paper. The process was evaluated for three different waste papers, brown and white paper tissues and white printing paper. Different pretreatment processes were investigated to further increase the cellulose liquefaction efficiency. By utilizing soda pretreatment, liquefaction efficiencies as high as 8896 were achieved. The obtained liquefaction products were fingerprinted by NMR and LDI-MS, while the solid residues were analyzed by XRD, SEM, TGA, and FTIR As industrial-scale microwave reactors are currently under development, the developed method displays significant potential for recycling waste paper to green platform chemicals at the industrial scale., QC 20150209

QC 20200310Non-duplicate with DOI: 10.1039/c7nh00104e ISI: 000418196800002 ScopusID: 2-s2.0-85038940009 PMID: 32254107

QC 20181218

QC 20170104

The highly flammable character of cellulose-rich fibers from wood limits their use in some advanced materials. To suppress the flammability and introduce flame-retardant properties to individual pulp fibers, we deposited nanometer thin films consisting of cationic chitosan (CH) and anionic poly(vinylphosphonic acid) (PVPA) on fibers using the layer-by-layer (LbL) technique. The buildup of the rnultilayer film was investigated in the presence and absence of salt (NaCl) using model cellulose surfaces and a quartz crystal microbalance technique. Fibers were then treated with the same strategy, and the treated fibers were used to prepare paper sheets. A horizontal flame test (HFT) and cone calorimetry were conducted to evaluate the combustion behavior of paper sheets as a function of the number of bilayers deposited on fibers. In HFT, paper made of fibers coated with 20 CH/PVPA bilayers (BL), self-extinguished the flame, while uncoated fibers were completely consumed. Scanning electron microscopy of charred paper after HFT revealed that a thin shell of the charred polymeric multilayer remained after the cellulose fibers had been completely oxidized. Cone calorimetry demonstrated that the phosphorus-containing thin films (20 BL is similar to 25 nm) reduced the peak heat release rate by 49%. This study identifies a unique and highly effective way to impart flame-retardant characteristic to pulp fibers and the papers made from these fibers., QC 20151203

Cellulose partially converted to dialcohol cellulose has been identified as a potential breakthrough material for the production of bio-based, complex, double-curved surfaces due to its extensive strain-at-break characteristics (reaching as great as 80% in tensile loading). Tensile testing of handsheets made from modified cellulose fibers was conducted from 50 to 90% relative humidity (RH) and from 23 to 150 °C. Strain-at-break of the handsheets ranged from 35 to 80% over this humidity and temperature range, which is significantly greater than typical cellulose-based materials. The combined effect of moisture and temperature was further investigated by dynamic mechanical thermal analysis, which was utilized to determine the glass-transition temperature of the handsheets as a function of relative humidity. Based on the tensile test results and verified by the three-dimensional (3-D) forming and simulation, a forming limit diagram (strain-based failure surface which describes and illustrates the formability of the material) for the handsheets was generated. This forming limit illustrates significant extent to which this bio-based material can be 3-D formed into advanced structures. Furthermore, temperature was identified as the best, quickest, and most controllable method of improving extensibility of this material during 3-D forming., QC 20170621

Biobased graphene oxide quantum dots (GOQD) were derived from cellulose via carbon nanospheres (CN) as intermediate products. Solid CN were synthesized from cellulose through microwave-assisted hydrothermal degradation of alpha-cellulose with H2SO4 as a catalyst at 160 degrees C. The obtained CN were further utilized for the synthesis of GOQD by a two-step reaction including 30 minutes of sonication followed by heating at 90 degrees C under O-rich acidic conditions (HNO3). This process broke down the 3D CN to 2D GOQD. The size of the synthesized GOQD was controlled by the heating time, reaching a dot diameter of 3.3 nm and 1.2 nm after 30 and 60 minutes of heating, respectively. The synthesis process and products were characterized by multiple analytical techniques including FTIR, TGA, SEM, TEM, XPS, XRD, BET, DLS and AFM. Interesting optical properties in aqueous solutions were demonstrated by UV/Vis and fluorescence spectroscopy. Finally we demonstrated that corresponding GOQD can be synthesized from waste paper. This production route thus uses renewable and cheap starting materials and relatively mild synthesis procedures leads to instant nanometric production of 2D dots. In addition it enables recycling of low quality waste to value-added products., QC 20150504

QC 20190225

QC 20190221

Not duplicate with DiVA 876264QC 20230202

Att minska plastavfall och uppmuntra återvinning har fått hög prioritet i många affärsverksamheter och olika typer av regleringar implementeras för att minska den negativa påverkan av plastanvändningen. Papper och kartong består i huvudsak av cellulosa som har många egenskaper som är essentiella för en hållbar ekonomi (t.ex. förnyelsebar, återvinningsbar och bionedbrytbar) och pappersprodukter kan ersätta plast i många applikationer. Återvinningsgraden för pappersförpackningar är i vissa områden redan hög men det finns fortfarande begränsningar i att använda återvunna fibrer i vissa applikationer. Återvunna fibrer kan innehålla mineraloljor som kan migrera och ansamlas i mat som lagras i förpackningarna. Utvecklingen av barriärer för papper och kartong är nödvändig för att öka graden av användningsområden för förpackningar. Laminering är en traditionell teknik som används för bestrykningar, dock kan metoden leda till lägre återvinningsgrad. Dispersionsbarriärer är en typ av barriär där en emulsionspolymer stelnar till en icke porös film på pappersytan. Dispersionsbarriärer är enkla att separera från pappret under återvinningsprocesser och bra barriäregenskaper kan uppnås redan för låga ytvikter. I denna masteruppsats testas tre olika pigment (kaolin, talk och kalciumkarbonat) i olika koncentrationer i styrenakrylat latex och effekten på barriäregenskaper utvärderas. Dispersionerna beströks på papper med hjälp av bänkbestrykning. Viskositeten mättes med en reometer och pigmenten tenderade att sänka viskositeten under lägre skjuvhastigheter. Mineraloljebarriäregenskaper testades genom att mäta migrationen av ett flyktigt kolväte (n-heptan) genom barriären. Oljeresistens testades med palmkärnoljemetoden och ingen oljemigration observerades efter 24 timmar. Vikt oljeresistens testades också för alla prover. Kaolin tenderade att ge sämre fettbarriär efter viktning, jämfört med talk. Detta förklarades genom att kaolin har en högre modul än talk vilket kan skapa sprickbi, Reducing plastic littering and encouraging recycling have become top priorities for many businesses, and regulatory actions are taken around the world to target the adverse effects of plastic materials. Paper and paperboards mainly consist of cellulose which has many properties that are essential for a sustainable economy (e.g., renewable, recyclable and biodegradable), and paper products can be an alternative for plastics in many applications. Although the recycling rate for paper and cardboard in some areas is already relatively high, there are still some concerns about using recirculated fibres in some applications. Recycled cardboard can contain mineral oil hydrocarbons which could migrate and accumulate in food during storage. Developing coatings for paperboards is necessary to increase the range of usage for paper products in packaging applications. A traditional way of coating paper is by lamination, but this technique tends to lead to lower recycling rates. Dispersion coating is a type of barrier where an emulsion polymer is applied and solidified to a non-porous protective film on the paper surface. Dispersion coatings are readily removed from the paper during recycling, and proper barrier functions can be achieved already at low coat weights. In this thesis, three different types of pigments (kaolin, talc, and calcium carbonate) were tested in different concentrations in a styrene acrylate copolymer latex, and the effect on barrier properties was evaluated. The dispersions were coated onto papers by rod coating. Viscosity tests were done by using a rheometer. The pigments tended to decrease viscosity at low shear rates. Mineral oil barrier properties were tested by measuring the migration of a volatile hydrocarbon (n-heptane) through the barrier. Grease resistance was tested with the palm kernel oil test, and no oil migration was observed in any of the samples after 24h. The effect of folding on barrier properties depending on the pigment type and conce

På pappersmaskin 11 i Hallsta pappersbruk tillverkas högglansigt papper som bleks med väteperoxid. Om väteperoxiden som finns kvar efter blekningen, kallat restperoxid, kommer ut på pappersmaskinen sliter detta på termovalsarna, vilket påverkar slutprodukten. Det finns en bakteriekultur på bruket, bestående av släktet Tepidiphilus som bryter ner väteperoxiden med hjälp av katalas och hindrar den från att komma ut på maskinen. Om bakterierna slås ut, av exempelvis ogynnsamma förhållanden, märks detta genom att restperoxiden ökar. Målet med detta arbete är att försöka identifiera vilka faktorer som påverkar bakterierna och lägga fram ett förslag för hur man kan förhindra uppkomsten av restperoxid. För att utföra detta användes i första hand principalkomponentanalys, samt så studerades hur olika faktorer förändrades i förhållanden till uppkomsten av restperoxid. Ett antal parametrar kunde identifieras baserat på tillgängliga data. Dock kan inga absoluta slutsatser dras då det inte går att bekräfta några teorier med labbförsök eller genom att manipulera processen. De parametrar som tros ha störst påverkan är mek. renat färg, rest-aluminium, grumlighet, manganhalten i vatten, pH för kar K0203, returmälden samt inloppslådan och klorhalterna som uppmätts för mek. renat total klor, RVV1 fri klor, varmvatten total klor och mek. renat fri klor. Dessa parametrar bör därför övervakas framåt, och kan i det fall att restperoxid återigen uppkommer antingen bekräftas eller dementeras deras faktiska påverkan och samspel för bakteriernas välmående., Paper machine 11 in Hallsta paper mill produces high-gloss paper that is bleached with hydrogen peroxide. If the hydrogen peroxide that remains after the bleaching, called residual peroxide, gets out on the paper machine, this wears down the thermal rollers, which affects the final product. There is a bacterial culture at the mill, consisting of the genus Tepidiphilus, which breaks down the hydrogen peroxide with the help of catalase and prevents it from getting out to the machine. If the bacteria are killed, for example by unfavourable conditions, this is noticeable by an increase in residual peroxide. The goal of this project is to try to identify which factors affect the bacteria and put forward a proposal for how to prevent the occurrence of residual peroxide. To carry this out, principal component analysis was primarily used, and how different factors changed in relation to the appearance of residual peroxide was studied. Several parameters could be identified based on the available data. However, no conclusive conclusions could be drawn as it is not possible to confirm any theories with lab tests or by manipulating the process. The parameters believed to have the greatest influence are coloration of mechanically cleaned water (mech. water), residual aluminium, turbidity, manganese content of the water, pH for tank K0203, the returning pulp suspension as well as the headbox and the chlorine levels for mech. water total chlorine, RVV1 free chlorine, hot water total chlorine and mech. water free chlorine. These parameters should therefore be monitored going forward, and if residual peroxide occurs again, their possible interactions and actual impact on the well-being of the bacteria can either be confirmed or denied

På pappersmaskin 11 i Hallsta pappersbruk tillverkas högglansigt papper som bleks med väteperoxid. Om väteperoxiden som finns kvar efter blekningen, kallat restperoxid, kommer ut på pappersmaskinen sliter detta på termovalsarna, vilket påverkar slutprodukten. Det finns en bakteriekultur på bruket, bestående av släktet Tepidiphilus som bryter ner väteperoxiden med hjälp av katalas och hindrar den från att komma ut på maskinen. Om bakterierna slås ut, av exempelvis ogynnsamma förhållanden, märks detta genom att restperoxiden ökar. Målet med detta arbete är att försöka identifiera vilka faktorer som påverkar bakterierna och lägga fram ett förslag för hur man kan förhindra uppkomsten av restperoxid. För att utföra detta användes i första hand principalkomponentanalys, samt så studerades hur olika faktorer förändrades i förhållanden till uppkomsten av restperoxid. Ett antal parametrar kunde identifieras baserat på tillgängliga data. Dock kan inga absoluta slutsatser dras då det inte går att bekräfta några teorier med labbförsök eller genom att manipulera processen. De parametrar som tros ha störst påverkan är mek. renat färg, rest-aluminium, grumlighet, manganhalten i vatten, pH för kar K0203, returmälden samt inloppslådan och klorhalterna som uppmätts för mek. renat total klor, RVV1 fri klor, varmvatten total klor och mek. renat fri klor. Dessa parametrar bör därför övervakas framåt, och kan i det fall att restperoxid återigen uppkommer antingen bekräftas eller dementeras deras faktiska påverkan och samspel för bakteriernas välmående., Paper machine 11 in Hallsta paper mill produces high-gloss paper that is bleached with hydrogen peroxide. If the hydrogen peroxide that remains after the bleaching, called residual peroxide, gets out on the paper machine, this wears down the thermal rollers, which affects the final product. There is a bacterial culture at the mill, consisting of the genus Tepidiphilus, which breaks down the hydrogen peroxide with the help of catalase and prevents it from getting out to the machine. If the bacteria are killed, for example by unfavourable conditions, this is noticeable by an increase in residual peroxide. The goal of this project is to try to identify which factors affect the bacteria and put forward a proposal for how to prevent the occurrence of residual peroxide. To carry this out, principal component analysis was primarily used, and how different factors changed in relation to the appearance of residual peroxide was studied. Several parameters could be identified based on the available data. However, no conclusive conclusions could be drawn as it is not possible to confirm any theories with lab tests or by manipulating the process. The parameters believed to have the greatest influence are coloration of mechanically cleaned water (mech. water), residual aluminium, turbidity, manganese content of the water, pH for tank K0203, the returning pulp suspension as well as the headbox and the chlorine levels for mech. water total chlorine, RVV1 free chlorine, hot water total chlorine and mech. water free chlorine. These parameters should therefore be monitored going forward, and if residual peroxide occurs again, their possible interactions and actual impact on the well-being of the bacteria can either be confirmed or denied

Att minska plastavfall och uppmuntra återvinning har fått hög prioritet i många affärsverksamheter och olika typer av regleringar implementeras för att minska den negativa påverkan av plastanvändningen. Papper och kartong består i huvudsak av cellulosa som har många egenskaper som är essentiella för en hållbar ekonomi (t.ex. förnyelsebar, återvinningsbar och bionedbrytbar) och pappersprodukter kan ersätta plast i många applikationer. Återvinningsgraden för pappersförpackningar är i vissa områden redan hög men det finns fortfarande begränsningar i att använda återvunna fibrer i vissa applikationer. Återvunna fibrer kan innehålla mineraloljor som kan migrera och ansamlas i mat som lagras i förpackningarna. Utvecklingen av barriärer för papper och kartong är nödvändig för att öka graden av användningsområden för förpackningar. Laminering är en traditionell teknik som används för bestrykningar, dock kan metoden leda till lägre återvinningsgrad. Dispersionsbarriärer är en typ av barriär där en emulsionspolymer stelnar till en icke porös film på pappersytan. Dispersionsbarriärer är enkla att separera från pappret under återvinningsprocesser och bra barriäregenskaper kan uppnås redan för låga ytvikter. I denna masteruppsats testas tre olika pigment (kaolin, talk och kalciumkarbonat) i olika koncentrationer i styrenakrylat latex och effekten på barriäregenskaper utvärderas. Dispersionerna beströks på papper med hjälp av bänkbestrykning. Viskositeten mättes med en reometer och pigmenten tenderade att sänka viskositeten under lägre skjuvhastigheter. Mineraloljebarriäregenskaper testades genom att mäta migrationen av ett flyktigt kolväte (n-heptan) genom barriären. Oljeresistens testades med palmkärnoljemetoden och ingen oljemigration observerades efter 24 timmar. Vikt oljeresistens testades också för alla prover. Kaolin tenderade att ge sämre fettbarriär efter viktning, jämfört med talk. Detta förklarades genom att kaolin har en högre modul än talk vilket kan skapa sprickbi, Reducing plastic littering and encouraging recycling have become top priorities for many businesses, and regulatory actions are taken around the world to target the adverse effects of plastic materials. Paper and paperboards mainly consist of cellulose which has many properties that are essential for a sustainable economy (e.g., renewable, recyclable and biodegradable), and paper products can be an alternative for plastics in many applications. Although the recycling rate for paper and cardboard in some areas is already relatively high, there are still some concerns about using recirculated fibres in some applications. Recycled cardboard can contain mineral oil hydrocarbons which could migrate and accumulate in food during storage. Developing coatings for paperboards is necessary to increase the range of usage for paper products in packaging applications. A traditional way of coating paper is by lamination, but this technique tends to lead to lower recycling rates. Dispersion coating is a type of barrier where an emulsion polymer is applied and solidified to a non-porous protective film on the paper surface. Dispersion coatings are readily removed from the paper during recycling, and proper barrier functions can be achieved already at low coat weights. In this thesis, three different types of pigments (kaolin, talc, and calcium carbonate) were tested in different concentrations in a styrene acrylate copolymer latex, and the effect on barrier properties was evaluated. The dispersions were coated onto papers by rod coating. Viscosity tests were done by using a rheometer. The pigments tended to decrease viscosity at low shear rates. Mineral oil barrier properties were tested by measuring the migration of a volatile hydrocarbon (n-heptane) through the barrier. Grease resistance was tested with the palm kernel oil test, and no oil migration was observed in any of the samples after 24h. The effect of folding on barrier properties depending on the pigment type and conce

Holocellulose fibers produced by mild delignification form strong fiber networks, without beating or dry-strength agents. Recently, sequential batch delignification using peracetic acid (PAA) on finely cut wood sticks resulted in high-quality holocellulose fibers. Here, single step PAA delignification is developed for wood chips, which is simpler and can be used for larger fiber batches (400 g) with similar, high yield (60%). Such fibers have 1.4% lignin, 25% hemicelluloses content and well-preserved cellulose and hemicellulose molar mass. The corresponding paper sheet materials with a porosity of ~ 50%, have a Young’s modulus of 9 GPa and a strength of 90 MPa. Holocellulose fibers can now be readily investigated for use in larger scale paper, molded fiber and polymer biocomposite materials applications, or for cellulose nanofibril preparation., QC 20210415

Oxygen delignification is widely used in the pulp and paper industry as a part of delignification process between the kraft cook and bleaching. However, its potential has not been fully utilized. Rather than an intermediate process between cooking and bleaching, oxygen delignification is a strong oxidizing agent with powerful effects on the pulp properties. In this work, the hypothesis that oxygen delignification has the potential to improve the pulp mechanical properties was investigated. Several pulps were produced by either kraft cooking or kraft cooking combined with a subsequent oxygen delignification stage to a similar kappa number and their properties were analyzed and compared. This methodology assessed the real oxidative potential of oxygen on the final fiber properties. Total fiber charge, pulp mechanical properties, fiber morphology, swellability and fiber nanostructure, were studied. The major part of this research investigated the relationship between the carboxylic acid groups, seen as total fiber charge, and the mechanical strength of the paper. The total fiber charge was evaluated by conductometric titration and correlated with the pulp swellability and mechanical properties. It was demonstrated that oxygen delignification could significantly increase the charge content and the swelling of the pulp when an extended oxygen delignification (i.e, higher delignification degree) was used. In addition, the tensile index of the sheets increased when the fiber charge after oxygen delignification was sufficiently high. The swelling of the different pulps was investigated by Schopper-Riegler degree (SR°), water retention value (WRV) and fiber saturation point (FSP). It was determined that the higher the fiber charge, the higher the swelling ability, regardless of the lignin content. High alkali impregnation was utilized in this study due to its potential to increase cooking yield. The yield was compared to kraft pulp cooked with standard and high alkali imp, Syrgasdelignifiering används i stor utsträckning inom massa- och pappersindustrin som en del av delignifieringsprocessen mellan sulfatkokningen och blekningen. Dess potential har dock inte utnyttjats fullt ut. Snarare än att bara se det som en enhetsprocess mellan kokning och blekning, så bör man utnyttja syrgasens starkt oxiderande förmåga som kraftfullt kan påverka massans egenskaper. I detta arbete undersöktes hypotesen att syrgasdelignifiering har potential att förbättra massans mekaniska egenskaper. Olika massor framställdes till ett liknande kappatalsintervall genom antingen sulfatkokning eller sulfatkokning kombinerat med ett efterföljande syrgassteg och deras egenskaper analyserades och jämfördes. Denna metod bedömde den verkliga oxidativa potentialen hos syre på de slutliga fiberegenskaperna. Speciellt studerades total fiberladdning, fiberns svällbarhet, massans mekaniska egenskaper, fibermorfologi och fibernanostruktur. En avgörande komponent i forskningen är sambandet mellan karboxylsyragrupperna, sedda som total fiberladdning, och papperets mekaniska styrka. Den totala fiberladdningen utvärderades genom konduktometrisk titrering och korrelerades med massans svällningsförmåga och mekaniska egenskaper. Det visades sig att syrgasdelignifiering avsevärt kunde öka laddningshalten och massans svällning när en utökad syrgasdelignifiering (dvs. högre delignifieringsgrad) användes. Dessutom ökade arks dragindex när fiberladdningen efter syrgasdelignifiering var tillräckligt hög. De olika massornas svällningsförmåga undersöktes genom mätningar av Schopper-Riegler-grad (SR°), vattenretentionsvärde (WRV) och fibermättnadspunkt (FSP). Från dessa kunde slutsatsen dras att ju högre fiberladdningshalt desto högre svällningsförmåga oavsett ligninhalt. Högalkaliimpregnering användes i denna studie för dess potential att öka utbytet. Utbytet jämfördes för sulfatmassa kokad med standard- och högalkaliimpregnering, följt av syrgasdelignifiering och blekning. Det observerades, Main funder: STFI IntressentföreningOther funders:Södra ForskningsstiftelseÖnnesjöstiftelsenStiftelsen Nils och Dorthi Troëdssons forskningsfondQC 2022-11-14