Emulsioner bildas då två vätskor som normalt sätt inte blandas med kraft vispas samman för att distribuera den ena vätskan i den andra. För att dessa vätskor inte efter avslutad vispning ska gå isär kan emulgeringsmedel tillsättas, till exempel polysackarider som hör till hydrokolloiderna. Hydrokolloider används inom livsmedelsindustrin för sin förmåga att påverka ett livsmedels reologiska egenskaper, så som viskositet och textur. Exempel på hydrokolloider som används inom den växtbaserade livsmedelsbranschen är derivat av cellulosa så som metylcellulosa. Metylcellulosan har egenskaper som löslighet i vatten samt termoreversibel gelatinering. Med detta menas att en lösning med metylcellulosa efter uppvärmning kommer att bilda en gel, men så fort temperaturen sjunker kommer viskositeten minska, och försvinna helt. Den huvudsakliga anledningen som ligger bakom intresset att utvärdera stabiliteten hos hydrokolloider är dagens allt större efterfrågan på växtbaserade proteinalternativ som efterliknar egenskaper hos de animaliska alternativen. Just stabiliteten av hydrokolloiderna är något som är svårt att utvärdera, men då kunskapen om konsistensgivare så som hydrokolloider blir allt större, ökar även möjligheten till bättre och fler modifierade proteinalternativ. Något som kan locka en större grupp konsumenter. Försöken som genomfördes gjordes med syftet att utvärdera egenskaperna hos metylcellulosa som konsistensgivare i en köttersättningsmix. En avgörande faktor vid beredningen är att kontrollera temperaturen. I försöken var den initiala temperaturer vid beredningen av emulsionerna innehållandes vatten, olja samt metylcellulosa antingen under 4°C eller över 4°C (10-15°C). Utöver detta  genomfördes även försök vid pH 5 samt pH 5,5. Metoder för att utvärdera stabiliteten hos emulsionerna utvecklades också. Data som erhölls bearbetades statistiskt och det visade sig att emulsioner tillverkade under 4°C hade en högre stabilitet än de som tillverkats vid temperaturer över 4°C. Skillnaden i stabilitet vid olika pH (pH 5,0 och pH 5,5) var däremot inte signifikant, men då försöken endast genomfördes med emulsioner med olja, vatten och metylcellulosa går det inte att med säkerhet säga att pH inte har någon signifikant effekt i en slutprodukt som även innehåller proteiner, stärkelse och kryddor. / Emulsions are formed when two liquids that does not combine naturally are mixed with force to distribute one liquid in the other. To prevent these liquids from separating when the mixing ends emulsifiers can be added, for example polysaccharides such as hydrocolloids. Hydrocolloids are used in the food industry for their ability to influence the rheological properties of a food, such as viscosity and texture. Examples of hydrocolloids used in the plant based food industry are cellulose derivates, such as methylcellulose. Methylcellulose has properties such as solubility in water and thermoreversible gelatinization. This means that the solution containing methylcellulose after heating will form a gel, but as soon as the temperature drops, the viscosity will decrease and vanish completely. The main reason to why a study of the stability in hydrocolloids is of interest is today's increasing demand for plant-based protein alternatives that largely have similar properties to the animal alternatives. The stability of hydrocolloids has previously been difficult to evaluate, but as knowledge about sensory enhancers such as hydrocolloids grows, so does the possibility of producing better and more reconstructed protein alternatives. Thus attracting a larger consumer group. The experiments that was carried out aimed at the evaluation of properties of methylcellulose as a sensory enhancer in a meat substitute mix. A critical point in the preparation is to control the temperature. The initial temperature during preparation of the emulsions containing water, oil and methylcellulose was either below 4°C or above 4°C (10-15°C). In addition, experiments were also performed at pH 5 and pH 5.5. Methods to measure the stability of the emulsions were also developed. The data obtained were processed statistically and the results indicated that emulsions prepared below 4°C had a higher stability than those prepared at temperatures above 4°C. Difference in stability due to pH, on the other hand, was not significant, but since the experiments were carried out with emulsions only containing oil, water and methylcellulose it is not possible to say with certainty that pH has no significant effect in a product containing more components such as protein, starch and spices.

Under de senaste åren, på grund av överanvändningen av icke förnybara resurser har den ekologiska miljön på jorden påverkats allvarligt. I takt med detta ökade oron bland människor om att resurserna skulle ta slut. Därför är det nödvändigt att utveckla och använda mer miljövänliga förnybara resurser. Ett av dessa alternativ är cellulosabaserat material, vilket är ett utmärkt val. Vanligtvis består cellulosabaserat material av ett förstärkande material (cellulosafiber) och en matris (polymer eller metall). Dock bör kompatibiliteten mellan cellulosamaterialet och polymermatrisen ses över, eftersom generellt är kompatibiliteten mellan de låg. I detta projekt studerades olika metoder för att förbättra kompatibiliteten mellan cellulosamaterialet och polymermatrisen. Två cellulosamaterial (mikrokristallin cellulosa (MCC) och cellulosaoxalat (COX)) behandlades med olika modifieringsmetoder för att förbättra kompatibiliteten och gränssnittsinteraktionen mellan materialen. För att modifiera MCC och COX användes bland annat kulmalning, vatten som dispergeringsmedel, förestring av cellulosafibrerna med oljesyra under olika reaktionstider (6, 18, respektive 48 timmar), samt att tillsätta ett kompatibiliseringsmedel, maleinsyraanhydrid-ympad polypropylen (MAPP), i olika halter (1% respektive 2%). För att framställa kompositproverna användes extrudering och formsprutning. Dragprovning genomfördes för att testa de mekaniska egenskaperna hos proverna. Ytterligare karakteriseringsanalyser som utfördes på de olika cellulosapulvren var kontaktvinkeln (CA), svepelektronmikroskopi (SEM), infrarödspektroskopi (FTIR), och röntgendiffraktion (XRD). Resultatet från dragprovningen visade att COX-proverna med 1% MAPP som kompatibilisator gav den högsta draghållfastheten och Youngs modul av alla kompositproverna som producerades i detta exjobb. Användningen av MAPP som kompatibiliseringsmedel visade ett bättre resultat än de andra undersökta metoderna för att förbättra kompatibiliteten mellan den hydrofila ytan på MCC/COX och den hydrofoba ytan på polymermatrisen. Att använda MAPP som kompatibilisator bör prioriteras vid tillverkningen av kompositmaterial. / In recent years, with the excessive use of non-renewable resources on the earth, the ecological environment has been seriously affected. At the same time, humans began to worry about running out of resources. Therefore, it is necessary to develop environmentally friendly renewable resources. Cellulose-based material is an excellent choice. Commonly, cellulose-based material consists of reinforcement (cellulose fiber) and matrix (polymer or metal). However, the compatibility between cellulosic material and polymer matrix should be considered. In general, the compatibility between them is poor. In this project, several methods to improve the compatibility between the cellulose material and polymer matrix were studied. Two cellulosic materials (microcrystalline cellulose (MCC) and cellulose oxalate (COX)) were treated with different modification methods to improve the compatibility and interfacial interaction between the cellulosic material and polymer matrix. Ball milling, using water as a dispersing agent, using oleic acid to esterify cellulose fiber for different reaction times (6 h, 18 h, and 48 h), and using different concentrations (1% and 2%) of maleic anhydride grafted polypropylene (MAPP) as compatibilizers were applied to improve the compatibility between cellulose fiber and polymer matrix.  To produce the composite specimens, extrusion and injection molding were utilized. Tensile testing was done to test the mechanical properties of the specimens. Contact angle (CA), scanning electron microscope (SEM), Fourier Infrared Spectrometer (FTIR), X-ray diffraction (XRD) were also performed on the various cellulose powders as characterization methods. According to the result of tensile testing, COX samples with 1% MAPP as compatibilizer, showed the highest tensile strength and Young’s modulus of all the composite samples produced in this master thesis. Using MAPP as a compatibilizer shows a better result than using other methods to improve the compatibility between hydrophilic MCC/COX surface and hydrophobic PP matrix. The use of MAPP as a compatibilizer should be prioritized when producing composite materials.

Biomass is the only renewable carbon source that can compete with fossil energy sources in terms of production of materials, chemicals and fuels. Biomass can be transformed into charcoal, liquid and gas through pyrolysis, i.e. pure thermal decomposition. By changing the pyrolysis conditions either solid, liquid or gaseous fractions can become the main product and pyrolysis is thus a very versatile process. Pyrolysis is also the first step in combustion and gasification, two important thermal processes in our society. The importance of biomass pyrolysis has led to extensive research in this area but due to the complexity of the process there is still no general understanding of how to describe biomass pyrolysis, which is essential in order to optimize thermal processes. The research presented in this thesis thus aims at finding a simple yet accurate way to model the decomposition rate of biomass during pyrolysis. Thermogravimetric analysis, a well known method that is simple to use, was chosen to collect the experimental data used for kinetic evaluation. The reaction kinetics were derived using two different model-free, isoconversional methods, i.e. the non-linear form of the Friedman method and the incremental, integral method ofVyazovkin. By using these two methods and experimental data, complete reactionrate expressions could be derived for commercial cellulose, Norway spruce and seven different samples originating from kraft cooking, the most common process to produce pulp for the paper industry. The derivation of model-free rate expressions have never been performed before for these materials and since the rate expressions are model-free, no assumptions or knowledge about the pyrolysis reactions were required. This is a great advantage compared to the commonly used model-fitting methods that rely on information about these aspects. All therate expressions were successful in predicting mass-loss rates at extrapolated pyrolysis conditions. This is a clear indication of the soundness of the methodologypresented in this thesis. / Biomassa är den enda förnybara kolkällan som kan konkurrera med fossila energikällor när det gäller produktion av material, kemikalier och bränslen. Biomassakan omvandlas till biokol, bioolja och gas med hjälp av pyrolys, dvs termisk nedbrytning. Genom att variera de processförhållanden som råder under pyrolysen kan man få antingen fast, flytande eller gasfasiga ämnen som huvudprodukt, något som gör pyrolys väldigt flexibelt. Utöver detta är pyrolys även betydelsefull vid förbränning och förgasning, två viktiga processer i dagens samhälle. Vikten av biomassapyrolys har resulterat i omfattande forskning inom området men pga biomassas komplexa natur råder det ännu ingen enighet gällande hur biomassapyrolys bör modelleras. Detta försvårar utveckling och optimering av termiska processer matade med biomassa. Forskningen som presenteras i denna avhandling fokuserar således på att finna en enkel men noggrann metod för att beskriva hastigheten med vilken biomassa bryts ned under pyrolys. Termogravimetrisk analys, en vanligt förekommande metod som är enkel att använda, valdes för att samla in experimentell data som kan användas för att undersöka hastigheten för termisk nedbrytning, dvs kinetiken. Två olika metoder som på engelska går under benämningen “model-free” och “isoconversional” har använts, nämligen den icke-linjära formen av Friedmans metod och den stegvisa, integrala metoden som utvecklats av Vyazovkin. Genom att använda dessa två metoder och experimentell data kunde kompletta reaktionshastighetsuttryck tas fram för kommersiell cellulosa, gran och sju olika material framställda genom sulfatprocessen, den idag vanligast förekommande pappersmassaprocessen. Pyrolyskinetiken för dessa material har aldrig tidigare analyserats med dessa två metoder och fördelarna med metoderna gjorde det möjligt att bestämma hastighetsuttryck utan någon kunskap om de pågående reaktionerna. Detta är en viktig fördel jämfört med andra metoder som är beroende av sådan information. Alla framtagna reaktionshatighetsuttryck kunde användas för att framgångsrikt förutsäga minskningen av massa vid extrapolerade pyrolysförhållanden. Detta är en tydlig indikation på att metoden använd i denna avhandling fungerar väl. / <p>QC 20160524</p>

The composition of lignin in the outer cell-wall layers of spruce and poplar has been studied and the data obtained have been compared with those of the mature reference wood in which the secondary cell wall predominates. Materials with exclusively or predominantly outer cell-wall layers were examined. Accurate data relating to the lignin monomer composition and the number of β-O-4´ bonds were obtained from pure middle lamella/primary cell wall lignin. Firstly, a 10 000 year old white spruce material, with most of the secondary cell wall missing, was studied. The aged lignin was composed of guaiacyl units only, and was slightly more condensed but otherwise similar to the reference lignin. Secondly, the developing xylem of a Norway spruce clone was analyzed during a growth season. In spring and early summer, growth is very rapid and the intention was to sample tissues in which the secondary cell-wall layers had not yet lignified, but where the outer layers at least had started to lignify. Microscopy, Klason lignin and carbohydrate analyses showed that the lignin in the developing xylem of samples from mid-June was located exclusively in the middle lamella. The lignin was more condensed, was composed of guaiacyl units only and contained more end-groups than the reference Norway spruce wood. Thirdly, the cambial tissues of a Balsam poplar clone were surveyed during a growth season. Both the phloem side and the xylem side of the cambial region were examined. The Klason lignin content and carbohydrate monomer distribution showed that in June and August the tissues on the phloem side contained material with mainly middle lamella/primary walls. In June, the xylem side in the cambial region contained mainly middle lamella/primary walls, and in August the secondary cell wall carbohydrates were being deposited. Both tissues contained lignin that was more condensed and had more end-groups than the reference lignin. In mid-June, the developing xylem had a ratio of syringyl to guaiacyl units of 0.6, whereas the ratio for the reference wood was 1.3. In the final study, lignin from the primary cell walls from a hybrid aspen cell suspension culture was investigated. The lignin contained only guaiacyl units which were more condensed than those observed in the reference poplar wood. / <p>QC 20100920</p>

In the early 1990’s, a lot of work was focused on extending the kraft cook to a low lignin content (low kappa number). The driving force was the need to further reduce the environmental impact of the bleaching, as less delignification work would be needed there. However, the delignification during the residual phase of a kraft cook is very slow and, due to its poor selectivity, it is a limiting factor for the lignin removal. If the amount of lignin reacting according to the residual phase could be reduced, it would be possible to improve the selectivity of the kraft cook. In the work described in this thesis, special attention has been given to the activation energy of the slowly reacting residual phase of a kraft cook on softwood raw material and to the influence of different cooking parameters on the amount of the residual phase lignin. The activation energy of the residual phase delignification of the kraft cook was shown to be higher than that of the bulk phase delignification. In order to decrease the amount of residual phase lignin, it was essential to have a high concentration of hydrogen sulphide ions when cooking with a low hydroxide concentration. It was also important to avoid a high sodium ion concentration when cooking with low hydroxide and low hydrogen sulphide ion concentrations. Furthermore, it was demonstrated that dissolved wood components had a positive effect on the delignification rate in the bulk phase of a kraft cook. The influence of different cooking parameters in the extended softwood kraft process on the bleachability (i.e. the ease with which the pulps can be bleached to a target brightness) of the manufactured pulp was also investigated. If variations in bleachability were seen, an attempt would also be made to find chemical reasons to explain the differences. It was difficult to establish clear relationships between the chemical structures of the residual lignin and the bleachability of the pulp. However, it was seen that the higher the content of β-aryl ether structures in the residual lignin after cooking, the better was the QPQP*-bleachability. In the middle/end of the 1990’s, the focus moved from extended cooking to efficient utilisation of the wood raw material, e.g. by interrupting the kraft cook at higher kappa number levels and choosing appropriate cooking conditions to maximise the cooking yield. A high cooking yield often leads to a somewhat higher hexenuronic acid (HexA) content of the pulp at a given kappa number. Therefore additional attention was devoted to how the HexA content and carbohydrate composition were affected, e.g. by a set of cooking parameters. Performing these studies it was also important to investigate the effects of a low HexA (after cooking) strategy on such vital factors as the cooking yield, the bleachability and the yellowing characteristics of the pulp obtained. It proved to be difficult to significantly reduce the HexA content in a kraft pulp by altering the cooking conditions for both softwood and the hardwood Eucalyptus Globulus. A reduction in HexA content can be achieved by extending the cook to lower kappa numbers, or by using a high hydroxide concentration, a low hydrogen sulphide concentration or a high sodium ion concentration. However, neither of these strategies is attractive for industrial implementation since they would result in an extensive loss of yield, viscosity and strength. / <p>QC 20100825</p>

Bomullsfibern har många fördelaktiga egenskaper som gör den allmänt omtyckt bland både konsumenter och producenter. Den vanligaste framställningen av fibern är konventionellt odlad bomull, men dessvärre har denna typ av framställningsprocess en negativ inverkan på miljön i form av hög kemikalieförbrukning och hög vattenanvändning. I samband med att bomullens negativa miljöpåverkan uppmärksammas, bidrar det till en ökad efterfrågan på miljövänliga fibrer med skonsammare processer. Denna studie har utifrån detta perspektiv undersökt, jämfört och testat förutsättningarna för att helt eller delvis ersätta bomull i trikåmaterial. De fibrer som har undersökts är de regenererade cellulosafibrerna Tencel, lyocell och modal. Dels har två hundraprocentiga material testats: Tencel A100 och lyocell, dels två fiberblandningar: bomull/modal och GOTS-bomull/Tencel LF. Samtliga material har bestått av rågarn med garntjocklek Ne 30/1 och stickats fram i en rundstickningsmaskin. Testerna som har utförts rör dimensionsstabilitet, spiralvridning, noppbildning, nötningshärdighet och slutligen draghållfasthet. För att säkerställa trovärdiga resultat har testerna genomförts upprepade gånger och därefter har ett medelvärde för varje material beräknats. De material som uppvisat bäst resultat avseende egenskaper och miljöpåverkan var Tencel A100 och lyocell, samt fiberblandningen GOTS-bomull/Tencel LF. / The cotton fiber has many advantageous properties which make it widely popular among both consumers and producers. The most common production of the fiber is conventionally grown cotton. This type of manufacturing process has unfortunately a negative impact on the environment because of its high chemical consumption and high water use. Since the negative environmental impact regarding cotton has got more attention, it has contributed to an increased demand for more environmentally friendly fibers with more eco-friendly processes. From this perspective, this study has examined, compared and tested the conditions for completely or partially replacing cotton in knitted materials. The fibers that have been examined are the regenerated cellulose fibers Tencel, lyocell and modal. Tencel A100 and lyocell have been tested independently and two fiber blends consisting of cotton/modal and GOTS-certified cotton/Tencel LF have been knitted and tested in this study. All materials have consisted of raw yarn with yarn thickness of Ne 30/1 and has been knitted in a circular knitting machine. The tests that have been carried out is dimensional stability, twisting, pilling resistance, abrasion resistance and finally tensile strength. To ensure reliable results, the tests have been done repeatedly and then an average value for each material has been calculated. The materials that showed the best results in terms of properties and environmental impact were Tencel A100, lyocell and the fiber mixture GOTS-certified cotton/Tencel LF.

<p>Detta examensarbete genomfördes från begäran av två företag, Pöyry Sweden AB, Karlstad och Kiram AB. Arbetet var uppdelat i två delar, en litteraturstudie samt en experimentell del. I litteraturstudien kartlades olika processer för framställning av dissolvingmassa och olika processer för beredning av viskosfiber. Utöver det sammanställdes även några av de ledande aktörerna av joniska vätskor samt applikationer för cellulosabaserade produkter. Fokus genom hela arbetet har legat på svavelfria processer som t.ex. användandet av joniska vätskor för upplösning av cellulosa. I den experimentella delen undersöktes det om man via en förhydrolys följt av ett soda-AQ kok, en svavelfri process, kunde producera dissolvingmassa. Utöver produktion av dissolvingmassa undersöktes också filtratet som drogs av efter förhydrolysen.</p><p>Under den experimentella delen varierades olika parametrar för att se hur det påverkade kvaliteten av massan. De parametrar som varierades vid förhydrolysförsöken var tid och antrakinon (AQ), för soda-AQ koket varierades tid, AQ och effektiv alkali (EA) halt. För ett förhydrolysförsök varierades även vätske/vedförhållandet. Vilka betingelser som skulle användas samt de mål som skulle uppnås fick man fram under litteraturstudien.</p><p>För att nå målet med ett utbyte på ca 85 % efter förhydrolysen krävdes en temperatur på 160°C och tid på 1 timme för en förhydrolys med enbart vatten. Hypotesen om att en AQ tillsats redan vid förhydrolysen skulle sänka utbytet visades inte stämma, man fick då istället ett ökat utbyte. Målet för massorna efter soda-AQ koket var ett utbyte på ca 40 %, ett kappatal runt 30 och en viskositet > 1000 ml/g. Utförde man en förhydrolys som beskrivits ovan följt av ett soda-AQ kok med dessa betingelser: temperatur 160°C, tid ≥ 2 h, EA sats > 21 % och en AQ halt ≥ 1 kg/ton, fick man en dissolvingmassa som uppfyllde kraven.</p><p>Kolhydratanalysen på filtratet visade att mestadels glukomannan brutits ner och lösts ut under förhydrolysen. Däremot skedde det ingen nedbrytning av cellulosa. Utförde man förhydrolysen på ett sådant sätt som beskrivits ovan bröt man ner en hemicellulosa mängd på ca 72 kg/ton flis. Det får ses som en ganska rejäl mängd eftersom man enbart använder vatten under förhydrolysen.</p> / <p>This project was carried out on a request from two companies, Pöyry Sweden AB, Karlstad and Kiram AB. The work was divided in two parts, one literature study and one experimental part. In the literature study different processes for production of dissolving pulp and different processes for viscose preparation were identified. Besides that, some of the lending companies of ionic liquids and some applications of cellulose based products were compiled. The main focus throughout this work has been on processes without sulfur, for an example the use of ionic liquids for dissolving cellulose. In the experimental part, dissolving pulp production by a prehydrolysis followed by a soda-AQ cooking was investigated. The filtrate gained from the prehydrolysis was also examined.</p><p>In the dissolving pulp production different parameters for the prehydrolysis and cooking stage were alternated. For the prehydrolysis the following parameters were varied: time and concentration of anthraquinone and for the cooking stage the parameters time, EA and concentration of anthraquinone. In one experiment the liquid to wood ratio was varied. The conditions that would be used and the target of the experimental work were received from the literature study.</p><p>To reach the target yield of approximately 85 % after an prehydrolysis, with water, the following conditions were required, a temperature of 160°C and a time of 1 hour. The hypothesis that an AQ additive, already in the prehydrolysis, should lowered the yield proved to be wrong. The target for the dissolving pulps after a soda-AQ cooking were a yield of ~ 40 %, a kappa number around 30 and finally a viscosity > 1000 ml/g. A soda-AQ cooking with these conditions: temperature 160°C, time ≥ 2 h, EA > 21 % and an AQ conc. ≥ 1 kg/ton, after a prehydrolysis, mentioned above, resulted in a pulp which achieved the targets.</p><p>The carbohydrate analysis on the filtrate showed that mostly glucomannan was settled out during the prehydrolysis. It also showed that no cellulose was settled out. A result after a prehydrolysis like the one mentioned above was that the amount of hemicellulose was reduced with ~ 72 kg/ton wood.</p>

This thesis is focused on the novel wood chip refining process called AdvancedThermomechanical Pulp (ATMP) refining. ATMP consists of mechanical pretreatmentof chips in Impressafiner and Fiberizer prior to first stage refining atincreased intensity. Process chemicals (this study was concentrated on hydrogenperoxide and magnesium hydroxide) are introduced into the first stage refiner.It is known that the use of chemicals in TMP process and first stage refining atelevated intensity can reduce the energy demands of refining. The downside is thatthey also alter the character of the produced pulp. Reductions in fibre length andtear index are usually the consequences of refining at elevated intensity. Additionof chemicals usually leads to reduction of the light scattering coefficient. Usingstatistical methods it was shown that it is possible to maintain the TMP character ofthe pulp using the ATMP process. This is explained by a separation of thedefibration and the fibre development phases in refining. This separation allowsdefibration of chips to fibres and fibre bundles without addition of chemicals orincrease in refining intensity. Chemicals are applied in the fibre developmentphase only (first stage refiner). The energy demand in refining to reach tensileindex of 25 Nm/g was reduced by up to 1.1 MWh/odt (42 %) using the ATMPprocess on Loblolly pine. The energy demand in refining of White spruce, requiredto reach tensile index of 30 Nm/g, was reduced by 0.65 MWh/odt (37%).Characterizations of individual fibre properties, properties of sheets made fromlong fibre fractions and model fibre sheets with different fines fractions werecarried out. It was established that both the process equipment configuration (i.e.the mechanical pre‐treatment and the elevated refining intensity) and the additionof process chemicals in the ATMP process influence fibre properties such as external and internal fibrillation as well as the amount of split fibres. Improvementof these properties translated into improved properties of sheets, made from thelong fibre fractions of the studied pulps. The quality of the fines fraction alsoimproved. However, the mechanisms of improvement in the fines quality seem tobe different for fines, generated using improved process configuration andaddition of process chemicals. The first type of fines contributed to better bondingof model long fibre sheets through the densification of the structure. Fines whichhave been influenced by the addition of the process chemicals seemed in additionto improve bonding between long fibres by enhancing the specific bond strength.The improved fibre and fines properties also translated into better airpermeability and surface roughness of paper sheets, properties which areespecially important for supercalendered (SC) printing paper. The magnitude offibre roughening after moistening was mainly influenced by the processequipment configuration while the addition of process chemicals yielded lowestfinal surface roughness due to the lowest initial surface roughness. There was nodifference in how fines fractions from the studied processes influenced the fibreroughening. However, fines with better bonding yielded model fibre sheets withhigher PPS, probably due to their consolidation around fibre joints. Hence, thedecrease in PPS can probably be attributed to the improvements in the long fibrefraction properties while the improvement of fines quality contributed to thereduction of air permeability.The process chemicals, utilized in the ATMP process (Mg(OH)2 and H2O2) alsoproved to be an effective bleaching system. Comparable increases in brightnesscould be reached using the ATMP process and conventional tower bleaching.Maximum brightness of the pulp was reached after approximately 10 minutes ofhigh‐consistency storage after refining or 40 minutes of conventional bleaching.This study was conducted using a pilot scale refiner system operated as a batchprocess. Most of the experiments were performed using White spruce (Piceaglauca). In Paper I, Loblolly pine (Pinus taeda) was used. It is believed that theresults presented in this thesis are valid for other softwood raw materials as well,but this limitation should be considered.

A large part of the world paper manufacturing consists of production of corrugated board components, kraftliner and fluting, that are used in many different types of corrugated boxes. Because these boxes are stored and transported, they are often subjected to changes in relative humidity. These changes together with mechanical loads will increase the deformation of the boxes compared to the case where the same loads are applied in a static environment. This enlarged creep due to the changes in relative humidity is called mechano-sorptive or accelerated creep. Mechano-sorptive creep forces producers to use high safety factors when designing boxes, and therefore, this is one of the key properties of kraftliner boards.   Different strategies to decrease mechano-sorptive creep, and to simultaneously gain more knowledge about the causes for this phenomenon in paper, are the aim of this work. Derivatised and underivatised black liquor lignins, a by-product produced in pulp mills in large quantities, have been used together with biomimetic methods, to modify the properties of kraftliner pulp. Furthermore, the properties of kraftliner pulp have been compared to other pulps in order to evaluate the influence of fibre morphological factors, such as fibre width and shape factor, on the mechano-sorptive creep. In addition the influence of the chemical composition of the kraftliner pulp has been evaluated both by means of treating a kraftliner pulp with chlorite and xylanase and by producing pulps with different chemical composition.   By using lignin and biomimetic methods, to create radical coupling reactions, it has been shown that it is possible to increase the wet strength of kraftliner pulp sheets. This method of treating the pulp showed, however, no significant effects on the mechano-sorptive creep. The addition of an apolar suberin-like lignin derivative, which has been shown to be possible to produce from natural resources, did show a positive effect on mechano-sorptive creep properties, but at the expense of stiffness properties in constant climate. Different pulps were compared with a kraftliner pulp and it was observed that the ratio between tensile stiffness and hygroexpansion can be used to estimate the mechano-sorptive creep properties. The hardwood kraft pulps investigated had lower hygroexpansion, probably due to more slender and straighter fibres, and higher tensile stiffness, probably due to lower lignin content. As the lignin content was varied by different methods in kraft pulps, it was observed that increased lignin content gives an increased hygroexpansion and decreased tensile stiffness as well as an increased mechano-sorptive creep. There were also indications of increased mechano-sorptive creep due to higher xylan content. / En stor del av världens papperstillverkning utgörs av produktion av wellpappkomponenter, kraftliner och fluting, som används i en uppsjö av olika wellpapplådor. När dessa lådor lagras och transporteras utsätts de ofta för förändringar i relativa luftfuktigheten. Dessa förändringar tillsammans med mekanisk belastning ökar lådornas deformation jämfört med om samma belastning skulle ha applicerats vid ett statiskt klimat. Denna förhöjda krypning på grund av förändringarna i relativ luftfuktighet kallas mekanosorptiv- eller accelererad krypning. Mekanosorptiv krypning tvingar producenterna att ha höga säkerhetsmarginaler vid dimensioneringar av lådor och är därför en av nyckelegenskaperna för kraftliner.   Olika strategier för att minska denna effekt, och på samma gång erövra mer kunskap om orsakerna till detta fenomen, har varit syftet med arbetet. Derivatiserade och oderivatiserade svartlutslignin, en biprodukt möjlig att få ut i stora kvantiteter från massabruk, har används tillsammans med biomimetriska metoder, för att modifiera kraftlinermassas egenskaper. Dessutom har kraftlinermassans egenskaper jämförts med andra massors egenskaper för att utvärdera inverkan av fibermorfologiska faktorer, såsom fiberbredd och fibreform på det mekanosorptiva krypet. Också inverkan av den kemiska sammansättningen av kraftliner massan har undersökts både genom behandling med klorit och xylanas och genom att producera massor med olika kemiska sammansättningar.   Genom att använda lignin och biomimetriska metoder för att skapa radikal-kopplingsreaktioner har det visats på möjligheten att öka våtstyrkan i massa-ark. Det här sättet att behandla massa visade dessvärre inga signifikanta effekter på det mekanosorptiva krypet. Tillsatts av ett apolärt suberin-liknande ligninderivat, som visats möjligt att producera ur naturliga råmaterial, visade en positiv effekt på det mekanosorptiva krypegenskaperna även om det var på bekostnad av styvheten vid konstant klimat. Olika massor jämfördes med en kraftlinermassa och det observerades att relationen mellan dragstyvhet och hygroexpansion kan användas för att uppskatta de mekanosorptiva krypegenskaperna. Lövvedssulfatmassorna som undersöktes hade lägre hygroexpansion, antagligen beroende på smalare och rakare fibrer, och högre dragstyvhet, troligen beroende på en lägre ligninhalt. När ligninhalten varierades i sulfatmassor med olika metoder observerades att ökad ligninhalt ger en ökad hygroexpansion och minskad dragstyvhet liksom en ökad mekanosorptiv krypning. Dessutom fanns indikationer på en ökad mekanosorptiv krypning till följd av högre xylaninnehåll. / QC 20100629

The surface charges of cellulosic fibers contribute to several papermaking operations that influence the manufacture and final properties of paper. This thesis investigates the effect of the surface charges on wet-end chemistry, e.g. through the interaction of cationic polyelectrolytes with the fiber surface charges, and on the network strength of pulp suspensions. The polyelectrolyte titration method was used to investigate the interaction of the fiber charges with cationic polyelectrolytes. Techniques were developed to fluorescent label the adsorbing cationic polyelectrolyte in order to visualize the adsorption behavior. Fluorescent confocal laser scanning microscopy (CLSM) was used to determine the extent to which the cationic polyelectrolyte adsorbs into the porous fiber wall. It was shown that the polyelectrolyte charge density limits the adsorption to the surface under electrolyte-free conditions. Adsorption into the fiber wall only occurs for two conditions: 1) if the molecular mass is sufficiently low or 2) the electrolyte concentration is high enough to screen the charges along the polyelectrolyte backbone but not the interactions between the polyelectrolyte and the fiber charges. Aside from the polyelectrolyte properties, the fiber charge density contributes to the adsorption behavior of cationic polyelectrolytes. The fiber charge profile was altered by bulk and surface carboxymethylation. The electrolyte concentration at which a deviation from 1:1 stoichiometry occurs was shown to be dependent on the amount of surface charges, such that the deviation in stoichiometry occurs at a higher electrolyte concentration for pulps having a higher surface charge. A hypothesis was developed to test the conditions at which the deviation in adsorption stoichiometry occurs, which was defined as the critical electrolyte concentration (CEC). It was found that the CEC corresponded to the electrolyte concentration at which the distance between the fiber charges was on the order of the Debye length. Electron spectroscopy for chemical analysis (ESCA) was used as an independent calibration procedure to validate for which a 1:1 stoichiometry occurs. The analysis with ESCA agreed well with the polyelectrolyte titration method for measurement of fiber surface charges. When measured under appropriate conditions, i.e. electrolyte concentration and molecular properties, the fiber surface charge can accurately be measured by the polyelectrolyte titration method. The charge profiles of various pulp types and treatments were also examined. Having been established as a valid technique, the polyelectrolyte titration method was again used to measure the surface charge while conductometric titration was used to measure the total charge content. The amount of bulk and surface charges vary depending on the pulping method and type of wood, although the ratio between the bulk and surface charge (i.e. the charge ratio) is similar for chemical pulps. The mechanical pulp has a higher charge ratio because it contains more fines material than chemical pulp. Bleaching of the chemical pulp decreases the amount of bulk and surface charges, although the charge ratio remains essentially constant. However, methods such as beating or carboxymethyl cellulose (CMC) grafting are available to increase the charge ratio. The effect of the charge profile on fiber-fiber interactions was studied on both a microscopic and macroscopic level. Colloidal probe microscopy (CPM) was used to investigate the microscopic interactions between two cellulose surfaces. Cellulose surfaces, prepared by spin-coating a dissolving pulp onto silica, were used to model the fiber surface, which is too rough for surface force measurements. The charge density of the model surface was increased by CMC grafting. Results showed that increasing the surface charge density created large electrosteric repulsions, due to CMC the chains protruding out from the surface. These interactions on the microscopic scale affect the fiber network strength, which was measured with a parallel plate rheometer. When the repulsion is increased between the fibers, caused by the increase in the surface charge, fiber flocs break apart more easily due to a reduced friction between the fiber surfaces. The forces acting on the fiber network can also be mechanical in origin. The fiber length and flexibility were altered in order to study the influence of mechanical surface linking and elastic fiber bending on the fiber network strength. Using the storage modulus (G’0) as a measure of fiber network strength, longer fibers were found to create a stronger network due to an increased amount of fiber contacts. Flexible fibers have a lower network strength than stiff fibers because the fibers come to rest in a less strained position such that the the influence of elastic fiber bending on the fiber network strength is predominant. / QC 20100831