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

After cooking, kraft pulps always contain not only residual lignin but also significant amounts of hexenuronic acid and other non-lignin structures oxidizable by permanganate under the standard kappa number determination conditions. These here referred to as false lignin. Like ordinary lignin, the false lignin also consumes bleaching chemicals, thus increasing both the production costs and the environmental impact of bleach plant effluents. The false lignin also has an effect on pulp properties such as brightness stability. This necessitates the development of efficient experimental routines for the determination of false lignin in different types of unbleached and bleached kraft pulps, together with studies of its formation, chemical behaviour, and ultimate fate. The main aim of this work has been to establish a method for the quantification of various types of oxidizable structures in bleached kraft pulps and to study their impact on pulp quality, particularly, on the brightness stability of pulps bleached in elemental-chlorine-free (ECF) and a totally-chlorine-free (TCF) processes. Part of this research deals with the relationship between the kappa number and the lignin content in the case of partly oxidized lignins. Spruce and birch kraft pulps processed according to the ODEQP and OQ(OP)Q(PO) bleaching sequences, respectively, have been analyzed. It has been found that the oxidation equivalent of the residual lignin decreases with increasing degree of oxidation along each bleaching sequence. This finding has been further supported by experiments with a number of model compounds. The Ox-Dem kappa number method has been shown to be an accurate means of determining the residual lignin content and of monitoring the efficiency of lignin removal along different bleaching sequences. It has been demonstrated that the kappa number can always be fractioned into partial contributions, the first of which comes from the residual lignin and is measured by the Ox-Dem kappa number, and the second from the false lignin and is given by the difference between the standard kappa number and the Ox-Dem kappa number. The effect of false lignin on the pulp kappa number is most pronounced in unbleached and oxygen-delignified kraft pulps. The extractability of residual and false lignin in different solvents has been investigated. The changes that occurred in the kappa number following different extraction steps have been compared with corresponding changes in the chemical composition and the conclusion has been drawn that the hemicellulose component of a kraft pulp is a major sourse of non-lignin structures contributing to the kappa number. The influence on the brightness stability of various oxidizable structures, viz.: residual lignin, hexenuronic acid and other non-lignin structures, in spruce, birch and eucalyptus kraft pulps bleached in ECF and TCF type processes was studied. It was demonstrated that the selective removal of all false lignin structures significantly improves the brightness stability. The degree of yellowing was found to be proportional to the content of HexA groups in pulps. It has been shown that 2-furancarboxylic acid, 5-formyl-2furancarboxylic acid and reductic acid are formed during the course of thermal yellowing. The influence of two bleaching sequences, D0(EP)D1 (ECF-type) and Q1(OP)Q2(PO) (TCF)-type, on the content of different oxidizable structures in eucalyptus kraft pulp was studied in relation to the brightness stability of the pulp. It was shown by kappa number fractionation that pulp bleached to full brightness with ECF- and TCF-type sequences contains different amounts of HexA. The most significant discoloration was observed in the case of TCF-bleached pulp having an especially high content of HexA. The mechanism of the moist (8 % moisture) thermal yellowing of fully bleached kraft pulps was further studied using dissolving pulp impregnated with a set of model compounds representing the most likely HexA degradation products, viz. as 2-furancarboxylic acid (FA), 5-formyl-2-furancarboxylic acid (FFA) and reductic acid (RA), either alone or in combination with Fe(II) or Fe(III) ions. It was found that the latter two acids take part in reactions leading to colour formation whereas 2-furancarboxylic acid does not. The effect of iron ions on the colour formation appears to vary with their oxidation state. The brightness loss caused by either FFA or RA, present in an amounts similar to the content of HexA in industrial pulps, was of the same order of magnitude as that observed in industrial pulps aged under the same conditions. Based on these findings, it is suggested that the overall mechanism of moist thermal yellowing involves several stages, including the degradation of hexenuronic acid and the formation of reactive precursors, such as 5-formyl-2-furancarboxylic acid and reductic acid. The presence of ferrous ions further enhances the discoloration. / QC 20101005

Variable data will play a decisive role in the future of packaging and product promotion. Variable data printing (VDP) is a technique whereby certain information can be altered in an otherwise static layout with the help of a digital printing system, and in the packaging industry a wide range of applications is possible. Inkjet printing, due to its non-impact printing (NIP) principle, is the most suitable technology to use when applying variable data on packaging and to offer customized and even personalized prints for the industry and the end-consumer (van Daele, 2005). The aim of the work described in this thesis was to evaluate the practicability of attaining high quality variable data print (VDP) at high speed. The thesis is divided into three major parts. Part one focussed on the surface topography of corrugated board and applicable analytical methods to describe the printability of the substrate. In the second part the performance of inkjet on corrugated board liners printed at high speed was investigated and how to achieve maximum printing resolution. The final part of the thesis is devoted to a market survey of variable data printing on the North American and European markets. Part 1 concentrated on corrugated board as substrate and its pre-conditions regarding surface topography before the printing operation. Most critical for the quality are print defects such as mottling, gloss and stripiness, all of which occur in the printing of corrugated board. Stripiness is especially critical because it is one of the most disturbing print defects on corrugated board since it is periodical and more easily perceived than random print defects (Netz, 1996). Part 1 revealed that there is a difference in surface micro-roughness between the regions on the peak line of the fluting and the regions in the valley between two peaks of the corrugation which leads to glossy lines on the peak areas. The aim of the second part was to assess the practicability of attaining high quality VDP at high speed on a variety of liners for corrugated board production. The trial was conducted on a Kodak Versamark DP5240 press in Örnsköldsvik, Sweden, in cooperation with the Mid-Sweden University - Digital Printing Centre (DPC). Nine different substrates were printed at speeds between 0.5 and 5 m/s. The results revealed that the paper type rather than the printing speed has the greatest influence on the print quality. Speed, however, is the most important technical factor for inline implementation of inkjet. To obtain a picture of the industries’ view of variable data print on fibre-based packaging, a market survey was initiated and was addressed to people in the development, marketing and decision-making sectors of the packaging and printing industry, including manufacturers of machinery, producers of packaging and prints, and print buyers. The goal was to draw an overview map covering the people’s view of their market, trends in their fields and how they envision the future of VDP on fibre-based packaging. The conclusion was that inkjet technology has to prove itself first and to increase its technical capability, and the printing industry will then start investing more in this technology and in applications such as VDP. / QC 20101206

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. 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. 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. 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. / 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. 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. 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. 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.

Wood consists not only of cellulose, lignin and hemicellulose but also of so called extractives which includes fats and acids and these components are separated in the mill from the black liquor. These extractives are in the mill denoted as tall oil soap. Tall oil has a large field of applications like chemicals and fuel and as it is produced to the atmosphere if it can replace oil and thus reduce the oil consumption. Tall oil soap is separated from the black liquor in a skimmer and the focus of this thesis was to examine the effect of air injection and the soap layer thickness on the soap separation efficiency in a skimmer. The work was focused on in analyzing the soap content of the inlet and outlet black liquor flow of the skimmer and to detect if an enhancement has been achieved with the two mentioned methods. The reason for the pulp mill to improve the soap separation efficiency was to decrease the risk of foaming and fouling in the evaporator but also to be able to increase the production of tall oil. The air injection gave a 41% improvement of the soap separation efficiency and further improvements are probably possible to achieve. The air injection flow was about 7 l air /m3 liquor in the black liquor feed. The airflow lowers the density of soap, creating a greater difference in density between soap and black liquor and this improves the separation efficiency. A thicker soap layer could increase the likelihood for soap drops to raise and reach the soap-liquor interface, because the soap drops have the tendency to bind with each other and will be separated from the liquor instead of following with the skimmed liquor outlet (fig. i.2). However, this study shows no indication of improvement with thicknesses that exceeds 0,75- 3,5 m which also endanger the skimmer due to overflow from the skimmer or create a short circuit between the in- and the outlet black liquor flow.

Nordic Paper Åmotfors tillverkar elektrotekniskt papper som används till att isolera lindningarna i transformatorer. Det är viktigt att bibehålla papprets egenskaper under en mycket lång tid då en transformators livlängd är lång. Syftet med detta examensarbete var att undersöka huruvida tillsats av en kemikalie bestående av dicyandiamid kan fördröja åldrandet av de papper som Nordic Paper tillverkar. Förhoppningen var att deras papper därefter skulle klara de krav-parametrar som finns för papper som åldrats i olja. Kemikalien som användes var Cartafix® WE liquid. Försök utfördes där olika kemikaliedoseringar tillsattes i mälden. Pappersark tillverkades och kvävehalten mättes därefter för att verifiera att kemikalien fastnat i de färdiga papprena. Pappers-arken åldrades sedan endera i olja eller i luft, och den kvarvarande polymerisationsgraden (DP) mättes. Sprängstyrke- och konduktivitetstester utfördes också. Papper som Nordic Paper tillverkat beströks med olika kemikaliedoseringar och samma tester utfördes även på dessa. Resultaten visade att retentionen av kemikalien var låg. Kvävehalten blev inte högre än 1 % och detta skedde vid 10-20 % kemikalietillsats. Efter åldring i olja minskade DP relativt mycket, vilket medförde att papprena inte uppnådde de uppsatta kraven (maximalt 50 % minskning). Tillsats av kemikalien förbättrade dock papprets åldringsegenskaper med nästan 45 % om icke-modifierat papper jämförs med det modifierade pappret som hade högst DP (10 % kemikalietillsats, vilket motsvarade 1 % kvävehalt). Papper som modifierats med kemikalietillsats i mälden gav lägre DP då åldringen skett i luft jämfört med icke-modifierat papper. DP minskade avsevärt efter åldring för papper som bestrukits med kemikalien. Kemikalietillsats försämrade både sprängstyrkan och konduktivteten. / Nordic Paper Åmotfors manufactures electro technical paper that is used to isolate the windings in transformers. It is important to maintain the properties of the paper during a long period of time because the life of a transformer is extensive. The purpose of this thesis was to investigate whether or not addition by a chemical consisting of dicyandiamide could delay the ageing of the papers that Nordic Paper manufactures. The aspiration was that their paper would then fulfil the requirements that are applicable to papers that have been aged in oil. The chemical that was utilised is called Cartafix® WE liquid. Experiments were conducted where different dosages of the chemical were added to the stock. Sheets of paper were manufactured and the nitrogen level was then measured in order to verify that the chemical had been fused in the finished paper. The paper sheets were then aged in either oil or air and the remaining degree of polymerisation was measured. Bursting strength and conductivity were also evaluated. Papers that Nordic Paper had manufactured were coated with different dosages of the chemical and then investigated in the same manner. The results showed that the retention of the chemical was relatively low. The nitrogen level did not exceed 1 %, which occurred at 10-20 % addition of the chemical. After ageing in oil, the degree of polymerisation was significantly reduced, which meant that the papers did not fulfil the requirement of a maximum of 50 % reduction. The addition of the chemical did however improve the ageing resistance with nearly 45 % if the unmodified paper is compared to the modified paper with the highest degree of polymerisation (10 % addition, equivalent to 1 % nitrogen). Papers that had been modified by addition of chemicals in the stock and had been aged in air exhibited lower degree of polymerisation than unmodified paper. The degree of polymerisation was significantly reduced for papers that had been coated and aged in air. Addition of chemicals resulted in both lower bursting strength and lower conductivity.

<p>The appearance and design of a package are key properties to attract and to focus the attention of a customer. Print quality contributes to a great degree to achieve these requirements. Most critical perceived in terms of quality are print defects like mottling, gloss and stripiness, which all appear in the printing of corrugated board. Stripiness is especially critical because it is a defect directly caused by the corrugated board construction. A further cause can be generated by the production process of corrugated board. Pre-studies by Odeberg Glasenapp (2004) revealed a difference in surface micro-roughness between the regions on the peak line of the liner and the regions in the valley between two peaks of the corrugation. This knowledge was the basis for the work described in this thesis.</p><p>In a first stage, laboratory trials were conducted with sets of coated and uncoated samples of various grammages. The trial was set-up in order to simulate the conditions in the corrugator as closely as possible. In the evaluations, it was found out that the settings were too high. For that reason, the coated samples were influenced to a too high degree and needed to be excluded from further evaluations. With the uncoated samples, on the other hand, a change in micro surface roughness was detectable. The roughness is decreased on the peaks and the gloss appearance was the conclusion. The analysis of the printed samples focused on shifts in colour and print density. It is unclear if both are affected only surface roughness changes and/or by the typical corrugated board effect of washboarding.</p><p>A full-scale test was performed in order to confirm the results of the laboratory test. A test series was chosen with coated and uncoated outer liners. Contrary to the lab-test results, the uncoated grades showed no surface roughness changes. Instead, the coated samples were affected to a great extent. The changes in surface roughness and gloss appearance were similar to the lab-test. This confirms that the lab-test samples were exposed to heat, pressure and shear to a too high degree. The print analysis of the full-scale test did not agree with the laboratory test. Gloss lines were visually detectable, but they were difficult to measure. A reason could be that the ink is capable on forming an ink film layer on top of the surface of the paper. This would cover the micro roughness of the matt parts thereby creating an almost homogeneous glossy appearance.</p>

Modern chemical technology is an efficient tool for solving problems, particularly within the complex environment of the pulp and paper industry, and the combination of experimental studies, mill data and mass balance calculations are of fundamental importance to the development of the industry. In this study various examples are presented, whereby chemical technology is of fundamental importance. It is well documented that under normal conditions the molten salt mixture from the kraft recovery boiler flows down into the dissolving tank without problems. However, in the case of  alternatives to the kraft recovery boiler, knowledge of more precise data of the molten salts is required for the design calculations. In this study the viscosity for the case of sodium carbonate and 30 mole% sulphide has been measured and is of the magnitude 2 – 3 cP at temperatures relevant for a recovery boiler, i.e. similar to water at room temperature. The presence of non-process elements (NPE) in a typical pulp mill has been investigated. The main input is with regards to the wood, and anticipated problems include; deposits in evaporators, high dead-load in liquor streams, plugging of the upper part of the recovery boiler and decreasing efficiency in the causticization department. Efficient green liquor clarification is of the greatest importance as an efficient kidney for many NPE. Mill data and calculations show that the magnesium added in the oxygen delignification does not form a closed loop. Integration of a prehydrolysis kraft pulp mill producing dissolving pulp with a plant producing viscose textile fiber could be highly beneficial. The prehydrolysis liquor will contain both sugars and acetic acid. It is however not possible to fully replace the sulphuric acid of the viscose spinning bath with acetic acid of own production. The sulphuric chemicals from the viscose plant can be partly taken care of in the kraft recovery area as well as the viscose plant which can be supplied with alkali and sulphuric acid. Zinc-containing effluents from the viscose plant can be treated with green liquor to precipitate zinc sulphide. / Modern chemical technology is an extremely efficient tool for solving problems particularly in a complicated environment such as the pulp and paper industry. Here, examples are studied during which chemical technology is of fundamental importance. At normal conditions the molten salt mixture from the kraft recovery boiler flows down into the dissolving tank without hindrance. However, for certain kraft recovery boiler alternatives, knowledge of more precise data of the molten salts is required. The viscosity for the case of sodium carbonate and 30 mole% sulphide has been measured and is of the magnitude 2 – 3 cP at relevant temperatures. The main input of non-process elements (NPE) is down to the wood, and known problems include deposits in evaporators and decreasing efficiency in the causticization department. Green liquor clarification is an efficient kidney for many NPE. Magnesium added in the oxygen delignification does not form a closed loop. Integration of a prehydrolysis kraft pulp mill producing dissolving pulp with a plant producing viscose textile fiber could be of significant interest, as the handling of both alkali and sulphuric compounds can be integrated. Problems will however arise as the capacity of the pulping line and the chemical recovery has to be adjusted.

Denna kandidatuppsats undersöker framtagningen av ett bakteriellt cellulosamaterial (BC-material), samt undersöker om materialets vattenavvisande egenskaper kan förbättras för att kunna möjliggöra användning som textilt material. Arbetet grundar sig i det faktum att BC- materialet är av en hydrofil karaktär, något som den brittiska designern Suzanne Lee utryckt vara ett problem för dess användningsmöjligheter. Arbetet behandlar en litteraturstudie av BC, vilken ligger till grund för en experimentel del där odling, vattenavvisande beredningar och vattenavvisande tester utförts. Gällande BC-produktion och materialframtagning har faktorer som pH-värde, temperaturförhållanden, och recept visat sig påverka cellulosaproduktionen. Ett varmare temperaturförhållande på 30°C jämfört med rumstemperatur (20- 22°C) har uppvisat bättre cellulosatillväxt. Detsamma gäller även för användandet av äppelcidervinäger i odlingmediumet, vilket uppvisat positiva resultat. Testerna av det framtagna BC-membranet har för det första kunnat bekräfta dess påstådda hydrofilitet. Vidare har även de vattenavvisande behandlingarna visat positiva resultat, även om användarmöjligheterna för materialet fortfarande anses vara begränsade inom det textila området. En ökning av kontaktvinkeln från 40,76° till 96,98° uppvisades efter att en behandling med en syntetisk vaxpolymer applicerats. Denna ökning på drygt 100 % skapade en kontaktvinkel över 90°, vilket teoretiskt betyder att materialets karaktär gått från hydrofilt till hydrofobt. Ett likvärdigt resultat uppvisades även efter en behandling med en vaxdendrimer. Materialet uppvisade dock tydliga resultat på att absorbera vatten vid längre tid av blötläggning, oavsett om det behandlats eller ej. / This bachelor thesis is investigating the development of a material based on bacterial cellulose (BC), as well as examine and test the material's hydrophobic properties. This is made in order to improve its user possibilities as a textile material. The motive is based on the fact that BC- materials have a hydrophilic nature, something that the British designer Suzanne Lee expressed as a problem for its user possibilities. The thesis process a literature study of BC, which is used for an experimental study where cultivation, water repellent treatments and water repellent tests are performed. Regarding BC-production and material creation, factors as pH-levels, temperature conditions and the recipes has shown to affect the cellulose production. The cellulose levels occurred to increase during a warmer condition at 30 °C compared to room temperature (20-22°C), both conditions where used for the cultivation. The same positive results also occurred when apple cider vinegar was used in the cultivation bath. The tests on the developed BC-membrane, initially confirmed its alleged hydrophilic nature. Furthermore, positive results occurred for the water repellant-treated materials, even if the user possibilities still is considered to be limited in the textile field. The contact angle increased from 40.76 ° to 96.98 ° on the material treated with a synthetic wax polymer, which results in a 100% increase. The angle of 90°, theoretically means that the character of the material changed from hydrophilic to hydrophobic. Similar results also occurred after treatment with a wax dendrimer. The material, however, showed significant results in absorbing water when subjected for a longer time of soaking, whether it was treated or not.

Biomass has been used as a fuel since ancient times. In recent decades the use has increased and the technology has developed considerably in large parts of the world. In Sub Saharan Africa, traditionally used biomass, such as wood or charcoal, is still the main source of energy in households. Zambia consumes charcoal corresponding to 6 089 000 tonnes/year. The use of biomass is very ineffective and with increasing population and energy requirements, this is placing Zambia on the top ten list of highest deforestation rates in the world.  Emerging Cooking Solutions Zambia Ltd. [ECS], started in 2012 with a vision to establish a pellet production in Africa. They provide modern cooking stoves and fuel pellets to counteract the unsustainable use of biomass and the health risk with traditional fuels. ECS aims to expand their production and are now striving to find a biomass that can increase hardness of pellets. The purpose of this work is to increase knowledge of the ability of raw materials to be pelletized, to support ECS expansion in a sustainable manner.  In this report fourteen different biomasses was evaluated at three different moisture content, 5%, 7,5% and 10%. Peanut shell, Pigeon Pea, Pine and Sicklebush was assumed to be able to be used as a base material. Remaining biomasses as additive; Bamboo, Cassava peel, Cassava stem, Eucalyptus, Gliricidia, Peanut shell, Lantana, Miombo seed capsules, Olive tree and Tephrosia. Pellet production was performed in a single pellet press located at the department of environmental and energy system at Karlstad University, Karlstad. Compression energy, friction energy, hardness and moisture uptake was some of the operating characteriztics and properties that were evaluated. Additionally, four blends were pelletized with the aim to increased hardness.  Pigeon Pea resulted in hardest pellets of the base materials, it managed a radial pressure of 46.3 kg, Pine resulted in low hardness, 17.7 kg. For the additives, the following materials were hardest as pellets; Tephrosia, 70.0 kg, Gliricidia 58.7 kg, Cassava peel 48.6 kg och Miombo seed capsules, 48.3 kg. Pine was the material that required relatively more energy pelletizing, 183.0 J. Lowest energy, Cassava stem, 49,1 J.  All blends resulted in higher hardness of pellets. Most advantageous were Cassava peel and Tephrosia. Cassava peel in Pigeon Pea increased hardness even at 10% and reduced energy requirements. Pigeon Pea with 50% Tephrosia increased hardness with 21.1 kg to 67.4 kg, slightly increasing energy requirements. Though logistic chain for Cassava peel was evaluated higher than Tephrosia.  For ECS to expand their production they are recommended, accordingly to the results in this study, to use Pigeon Pea at about 6% moisture content, as a base material. In order to increase hardness of pellets, they should primarily use Tephrosia, about 7% and Cassava peel at approximately 8% moisture content as an additive. / Biomassa har använts som bränsle sedan urminnes tider. Användningen har ökat och olika tekniker för nyttjande har utvecklats avsevärt i stora delar av världen de senaste decennierna. I Afrika söder om Sahara utgör traditionellt använd biomassa, såsom ved eller träkol fortfarande den huvudsakliga källan till energi i hemmet. Zambia konsumerar träkol motsvarande 6 089 000 ton ved varje år. Användningen av biomassan är mycket ineffektiv och med en ökande befolkning och energibehov sätter detta Zambia på topp tio listan med högsta avskogningshastigheter i världen.  Emerging Cooking Solutions Zambia Ltd [ECS], startade 2012 med visionen att etablera en pelletsproduktion i Afrika. De tillhandahåller moderna pelletsbrännare och producerar bränslepellets för att motverka problemet med den ohållbara användningen av biomassa och hälsorisker i samband med detta. ECS har som mål att öka sin produktion och eftersträvar nu främst att hitta en spetsråvara som kan öka hårdheten på pellets. Syftet med denna rapport är att öka kunskapen om råvarors möjlighet att pelleteras för att bidra till att Emerging Cooking Solutions verksamhet ska kunna expandera på ett hållbart sätt.  I denna rapport utvärderades fjorton olika biomassor vid tre olika målfukthalter 5%, 7,5% och 10%. Jordnötsskal, Pigeon Pea, Pine och Sicklebush ansågs kunna användas som basdrift, resterande biomassor som spetsråvaror, Bambu, Cassavaskal, Cassavastam, Eucalyptus, Gliricidia, Lantana, Miombo, Olivträd och Tephrosia. Pelletsproduktion gjordes i en enpetare vid Karlstads universitet, avdelningen för miljö-, och energisystem. Kompressions- och friktionsenergi samt hårdhet och fuktupptag är några av de variabler som testades, dessutom pelleterades fyra blandningar av olika biomassor med syfte att öka hårdheten på pellets.  De basmaterial som resulterade i hårdast pellets var Pigeon Pea som klarade ett radiellt tryck på 46,3 kg, Pine medförde låg hårdhet, 17,7 kg. Av spetsråvarorna medförde följande högsta hårdhet på pellets, Tephrosia, 70 kg, Gliricidia 58,7 kg, Cassavaskal 48,6 kg och Miombo frökapslar, 48,3 kg. Vid kompressionsstudierna visade sig Pine kräva relativt hög energi vid komprimering, 183,0 J. Lägst Cassavastam 49,1 J.  Samtliga blandningar med Tephrosia, Cassavaskal eller Gliricidia som spetsråvaror medförde hårdare pellets. Mest fördelaktigt som spetsråvara var Tephrosia och Cassavaskal. Cassavaskal ökade hårdheten redan vid 10% inblandning i Pigeon Pea och minskade samtidigt energibehovet. Vid inblandning av 50% Tephrosia i Pigeon Pea ökade hårdheten mest av samtliga blandningar med 21,1 kg till 67,4kg. Logistikkedjan bedömdes dock bättre för Cassavaskal än för Tephrosia.  ECS skulle enligt resultaten i denna studie kunna använda sig av Pigeon Pea vid cirka 6% fukthalt för att bredda sin råvarubas. För att öka hårdheten på pellets bör de i första hand använda sig av Tephrosia cirka 7% och Cassavaskal cirka 8% fukthalt som spetsråvara.