För att skapa ett hållbart samhälle måste material av fossilt ursprung ersättas med förnyelsebara och miljövänliga alternativ. Ett sådant alternativ är cellulosa från vedfibrer, som har stor potential att kunna ersätta många fossila material i framtiden. För att kunna uppnå detta behöver cellulosans egenskaper först modifieras för att passa olika ändamål och helt kunna ersätta fossila alternativ. I detta kandidatexamensprojekt modifierades blekt sulfatmassa, oblekt sulfatmassa, dissolvingmassa och kemitermomekanisk massa (CTMP) genom att introducera kvartära aminer med hjälp av två olika reagens, 2,3-epoxypropyltrimetylammoniumklorid (EPTMAC) och 3-kloro-2-hydroxypropyltrimetylammoniumklorid (CHPTAC). Under projektet undersöktes reagensens reaktionseffektivitet för de olika massorna genom att mäta substitutionsgraden (DS), hur förbehandling i form av torkning och malning påverkar modifieringsreaktionen och den modifierade massans egenskaper, utgångsmassornas svällningsegenskaper, samt mekaniska egenskaper som e-modul, brottstyrka och brottöjning hos pappersark tillverkade av modifierad massa. Resultaten från studien visar att det reaktionseffektivaste reagenset var CHPTAC som gav upphov till en genomgående högre effektivitet än samtliga modifieringar med EPTMAC, men att effektiviteten för respektive reagens är mindre beroende av pappersmassans komposition. Modifiering resulterade i att alla massor fick högre styrka i form av e-modul, brottstyrka och brottöjning. De mekaniska egenskaperna följde inte samma trend som substitutionsgraderna, vilket var oväntat. För att kunna dra mer pålitliga slutsatser skulle ytterligare studier behöva genomföras, inklusive upprepade modifieringar med varierande mängd reagens, mekaniska tester samt analys av ytterligare egenskaper som fibrernas ytor, kristallstruktur och längden på cellulosafibrerna.

Cellulose nanofibrils (CNF) is a renewable material with unique strength properties. A difficulty in CNF production is that CNF suspensions contain large amounts of water. If CNF suspension volume can be decreased by dewatering facilitated by centrifugation, then transportation costs and storage costs can be reduced. The aim of this thesis is to investigate the impact various parameters have on CNF centrifugation dewatering and identify optimal conditions for maximal water removal. A laboratory study was conducted using four materials; 2.0 w% enzymatically treated CNF (CNF1), 1.9 w% carboxymethylated CNF (CNF2) and two commercial samples (1.9 w% CNFA and 1.8 w% CNFB). The main method was analytical centrifugation up to 2330 g. Parameters tested were initial concentration before centrifugation, temperature, NaCl addition, pH, and applied solid compressive pressure (g-force and surface weight). In addition to centrifugation experiments the four materials were characterized with laser diffraction, UV-vis absorption, Dynamic light scattering, and dry weight measurements. Analysis of the experimental data collected show that increase in initial concentration give a higher final concentration, but less water is removed. Furthermore, temperature changes have no effect on separation of CNF and water. At an applied solid compressive pressure of 3 kPa and initial concentration at 1.5 w% the concentrations 5.5 w%, 1.5 w%, 4.0 w%, and 4.3 w% can be reach for CNF1, CNF2, CNFA, and CNFB respectively. After extrapolation of polynomial functions fitted to experimental data an applied solid compressive pressure of 22 kPa and initial concentration at 1:5 w%, the concentrations 9.1 w%, 1.5 w%, 6.9 w%, and 7.9 w% are predicted for CNF1, CNF2, CNFA, and CNFB respectively. The thickening of CNF suspensions achieved and predicted in this thesis implies possibilities for large amounts of water removal, e.g. the water content in a CNF1 suspension is reduced from 65.7 litres/kg CNF to 10.0 litres/kg CNF at the solid compressive pressure 22 kPa. The concentrations at 22 kPa are determined by extrapolation from experimental data <3 kPa solid compressive pressure. The carboxymethylated CNF2 can not be dewatered unless it is diluted or if salt or pH is adjusted. This is directly correlated to the electrostatic forces in the suspension and the Debye length. Addition of salt or lowered pH also eliminate any concentration gradients in diluted and centrifuged CNF2 suspensions. / Cellulosa nanofibriller (CNF) är ett förnybart material med unika styrkeegenskaper. En svårighet med produktion av CNF är att CNF suspensioner innehåller stora mängder vatten. Om volymerna av CNF suspensioner kan minskas med avvattning genom centrifugering, då kan transport- och lagerkostnader sänkas. Målet med det här examensarbetet är att undersöka vilken inverkan olika parametrar har på CNF-avvattning genom centrifugering och identifiera optimala förhållanden för maximalt avlägsnande av vatten. En laboratoriestudie utfördes på fyra olika material. De fyra materialen är 2 w% enzymatiskt behandlad CNF (CNF1), 1.9 w% karboxymetylerad CNF (CNF2) och två kommersiella prover (1.9 w% CNFA och 1.8 w% CNFB). Den huvudsakliga metoden var analytisk centrifugering upp till maximalt 2330 g. De testade parametrarna var initial koncentration innan centrifugering, temperatur, NaCl tillsats, pH, och applicerat fast kompressionstryck (g-kraft och ytvikt). Förutom centrifugeringsexperimenten så karaktäriserades the fyra mmaterialen med laser diffraktion, UV-vis absorption, dynamisk ljusspridning och vägningar av torrhalt. Analys av den experimentella data som insamlats visar att en ökad initial koncentration ger en högre slutkoncnentration, men mindre vatten kan bortföras. Temperaturförändringar har ingen effekt på separation av CNF och vatten. Vid ett applicerat fast kompressibelt tryck på 3 kPa och en initial koncentration 1.5 w% kan koncentrationerna 5.5 w%, 1.5 w%, 4.0 w%, och 4.3 w% nås för CNF1, CNF2, CNFA, och CNFB. Efter extrapolering av polynoma funktioner passad till experimentell data förutspås att koncentrationerna 9.1 w%, 1.5 w%, 6.9 w%, och 7.9 w% kan nås för CNF1, CNF2, CNFA, and CNFB vid 22 kPa och en initial koncentration på 1.5 w%. Förtjockningen av CNF suspensioner som kan, eller förutspås kunna nås genom centrifugering i det här examensarbetet innebär att det är möjligt att avlägsna stora mängder vatten, till exempel kan vatteninnehållet i CNF1 minskas från 65.7 liter/kg CNF till 10.0 liter/kg CNF vid 22 kPa fast kompressionstryck. Koncentrationerna vid 22 kPa fast kompressionstryck är extrapolerade från exprimentell data <3 kPa fast kompressionstryck. Den karboy- metylerade CNF2 kan inte avvattnas om den inte späds ut eller om salt eller pH justeras. Detta är direkt kopplat till de elektrostatiska krafterna i suspensionen och Debye längden. Tillsats av salt eller sänkt pH eliminerar också de koncentrationsgradienter som kan förekomma i utspädda centrifugerade CNF2 suspensioner.

Transparenta papper tillverkade av cellulosa nanofibriller (CNF), visar stor potential att kunna ersätta petroleumbaserade plaster inom många användningsområden, till exempel för mat- och varuförpackningar. CNF, även känt som nanocellulosa, kombinerar viktiga cellulosaegenskaper, med unika egenskaper hos nanomaterial. Denna kombination av egenskaper möjliggör tillverkning av ett pappers-liknande material som uppvisar både utmärkta mekaniska egenskaper och hög transparens. Användningen av nanocellulosa är dock förknippad med diverse utmaningar, för att materialet ska kunna bli kommersiellt slagkraftigt. En av de främsta utmaningarna är nanocellulosas höga affinitet för vatten och dess höga specifika yta som försvårar hanteringen av materialet. Avvattningen av nanocellulosadispersioner, för att tillverka transparenta papper, kan ta upp till flera timmar. För att övervinna detta hinder, har avdelningen för Fiberteknologi vid KTH tillsammans med BillerudKorsnäs AB, nyligen utvecklat en metodik för att skapa så kallade själv-fibrillerande fibrer (SFFer). Dessa fibrer möjliggör en snabbavvattnad papperstillverkningsprocess med makroskopiska vedbaserade fibrer, som efter tillverkning av pappret omvandlas till ett nanocellulosapapper, det vill säga ett nanopapper. För att erhålla SFFer krävs det att höga koncentrationer av karboxyl- och aldehydgrupper introduceras i cellulosafibrerna. Införandet av dessa funktionella grupper, möjliggör självfibrilleringen då SFFerna utsätts för moderata alkali-koncentrationer. I den ursprungliga studien som utfördes av Gorur m.fl., introducerades de funktionella grupperna med hjälp av sekventiell TEMPO- och periodatoxidation. I detta examensarbete, har alternativa kemiska metoder för att introducera samma kemiska funktionalitet som TEMPO-periodatsystemet undersökts. Huvudsyftet med arbetet är att besvara frågan: Hur påverkar olika kemiska behandlingar vid SFF tillverkningen, de kemiska och fysikaliska egenskaperna hos de modifierade fibrerna, samt de slutgiltiga pappersegenskaperna? För att besvara frågan, preparerades fibrer med liknande karboxyl- och aldehydinnehåll med hjälp av följande tre kemiska metoder: 1) TEMPO- följd av periodatoxidation (detta kommer att användas som referenssystem); 2) periodat- följd av kloritoxidation; 3) karboxymetylering följd av periodatoxidation. Egenskaperna hos fibrerna undersöktes med avseende på aldehyd- och karboxylinnehåll, avvattningspotential och förmåga att självfibrillera. Papper tillverkades med hjälp av en vakuumfiltreringsuppställning och följande egenskaper undersöktes hos pappret: mekaniska egenskaper (dragstyrka, brottsyrka och Young’s modul); optiska (transparens och ytreflektion); samt syrgaspermeabilitet. De erhållna fibrerna från samtliga tre kemiska modifieringar visade på självfibrillerande egenskaper i alkaliska lösningar. Detta beteende styrker hypotesen att ett strategiskt införande av ett högt karboxyl- och aldehydinnehåll leder till självfibrillerande fibrer. Transparenta papper tillverkade av fibrer som utsatts för TEMPO-periodatoxidation samt klorit-periodatoxidation, visade på utmärkta mekaniska egenskaper, hög transparens och bra barriäregenskaper - jämförbara med vad som vanligen kan noteras hos papper tillverkat av nanocellulosa. Samtliga egenskaper förbättrades ytterligare efter fibrillering av fibrerna i papperen. De karboxymetylerade-periodatoxiderade materialet, å andra sidan, uppvisade andra egenskaper jämfört med de två, tidigare nämnda, metoderna. TEMPO-periodat- och periodat-klorit-pappersmassan var halvgenomskinlig och geléliknande, medan den karboxymetylerade-periodatoxiderade massan var mer lik det omodifierade materialet. Detsamma gällde det tillverkade pappret som liknade ett konventionellt papper. Det var inte heller möjligt att åstadkomma en fibrillering av det karboxymetylerade-periodatoxiderade-pappret som utsattes för behandling med alkaliska lösningar. Avvattningstiden vid papperstillverkningen varierad mellan 4 och 60 sekunder, och karboxymetylering-periodat oxidation visade på snabbast avvattningstid. Den förlängda avvattningstiden i jämförelse med studien utförd av Gorur m.fl., tros främst bero på att ett filtreringsmembran med mindre porer användes på vakuumfiltreringsuppställningen, istället för en avvattningsvira som tidigare använts. Sammanfattningsvis så har det visat sig möjligt att tillverka självfibrillerande fibrer med hjälp av samtliga tre undersökta kemiska modifieringar. SFFer möjliggör tillverkning av snabbavvattnade transparenta nanocellulosapapper och visar på så vis på hög potential att kunna ersätta olje-baserade plaster till många förpackningsapplikationer. / Transparent papers made from cellulose nanofibrils (CNF), derived from e.g. wood, show great potential to replace petroleum-based plastics in many application areas, such as packaging for foods and goods. CNF, also known as nanocellulose, combine important cellulose properties with the unique features of nanoscale materials, gaining paper-like materials with outstanding mechanical properties and high transparency. However, nanocellulose faces various challenges in order to make the products commercially competitive. One of the main challenges is accompanied with nanocelluloses’ high affinity for water, which makes processing difficult. Dewatering of a nanocellulose dispersion in order to produce transparent paper may take up to several hours. To overcome this obstacle, the Fibre technology division at KTH Royal Institute of technology and BillerudKorsnäs AB have recently developed a new concept of self-fibrillating fibres (SFFs). This material enables fast-dewatering papermaking using fibres of native dimensions and conversion into nanocellulose after the paper has been prepared. In order to obtain SFFs, proper amounts of charged groups and aldehyde groups need to be introduced into the cellulose backbone. When SFFs are exposed to high alkali concentration, i.e. > pH=10, the fibres self-fibrillates into CNFs. In the original study, the functional groups were introduced through sequential TEMPO oxidation and periodate oxidation. In this work, alternative chemical routes have been examined to prepare SFFs with the same functional groups as introduced with the TEMPO-periodate system. The aim of the thesis has been to answer: how does different chemical routes to prepare transparent nanopaper made from SFFs affect the chemical and physical properties of the modified fibres, as well as the final physical properties of the transparent papers? To answer the question, fibres with similar carboxyl and aldehyde contents were prepared using three chemical routes: 1) TEMPO oxidation followed by periodate oxidation (which was used as reference system); 2) periodate oxidation followed by chlorite oxidation; 3) carboxymethylation followed by periodate oxidation. The properties of the fibres were examined regarding aldehyde and carboxyl content, dewatering potential and self-fibrillating ability. Papers were produced using a vacuum filtration set-up and the properties investigated were the mechanical; tensile strength, strain at failure and Young’s modulus, the optical properties; transparency and haze, as well as the oxygen permeability. In order to investigate the impact of the fibrillation of the papers, the properties were measured for both unfibrillated and fibrillated samples. Furthermore, the gravimetric yield after each chemical modification procedure was examined, as well as the dewatering time during sheet making. Fibres obtained from all three chemistries demonstrated self-fibrillating properties in alkaline solutions. This strengthens the hypothesis that the strategical introduction of aldehydes and carboxyl groups is the main feature responsible for the self-fibrillating ability of the fibres. Transparent papers made from fibres treated through TEMPO-periodate oxidation and periodate-chlorite oxidation showed excellent mechanical, optical and barrier properties, comparable to those seen in nanocellulose papers. The properties were further increased after fibrillation. The carboxymethylated-periodate oxidized fibres, on the other hand, behaved differently from the others. While the TEMPO-periodate and periodate-chlorite pulp was semi-translucent and gel-like, the carboxymethylated-periodate oxidized fibres resembled more the unmodified material. Likewise, the properties of those papers resembled conventional paper and no fibrillationwas experienced after immersing the papers in alkaline solution, according to the same protocol developed for the other two chemistries. The dewatering time during sheet making ranged from 4–60 seconds (carboxymethylation-periodate oxidation showing the fastest dewatering rates). The increased dewatering time compared to earlier studies is believed to mainly be due to the use of a filtration membrane on the vacuum filtration set-up, instead of a metallic wire with larger pores. Overall, SFFs was successfully produced using three different chemical routes. SFFs enables production of fast-dewatering transparent nanocellulose papers that shows the potential to replace oil-based plastics in many packaging applications.

<p>Paper that is subjected to moisture undergoes dimensional changes. It expands during moistening and shrinks during drying. When the paper is under tension between rollers, the effects are complex since shrinkage and expansion are restricted in the width direction. Waves can then appear on the paper web. This can be a problem in heatset web offset printing. The problem is known as waviness or fluting. The printed papers exhibit a wavy shape, which is visually disturbing due to light reflections which create glossy streaks. The aim of the work described in this thesis was to develop a method suitable for studying the moisture- and tension-induced waviness. Experiments were carried out on a laboratory scale to study how such waves develop during moistening and drying. The experimental setup was based on a modified tensile tester. A CCD camera and image analysis based on the STFI-OptiTopo technique was used to characterise the waviness. Moistening and drying were achieved by changing the surrounding air humidity. The method was used to study the effect of moisture uptake by the paper, and to evaluate the effect of tension on the waviness. It was found that increasing moisture resulted in a higher waviness amplitude, but that the web tension controlled the wavelength of the waviness. A high tension gave rise to a shorter wavelength. The measured wavelength was compared with a previously suggested model and the predicted wavelength was about twice as high as the measured wavelength.</p> / <p>When paper becomes damp it can develop waves which can be a problem with heatset web offset printing. Paper with waves may have glossy streaks after printing. Laboratory experiments studied the effect of moisture uptake by the paper. Readings were taken at a range of air humidities. The effect of tension on the waviness was also measured. The waviness was characterised using a charge coupled device (CCD) camera and the STFI-Packforsk OptiTopo technique to analyse the images. When the humidity was increased the amplitude of the waves increased. A high tension resulted in shorter wavelengths. Results from a previous model were used as a comparison.</p>

Varje år producerar H&amp;M ungefär 45 miljoner kg svart tyg. Den svarta färgningen görs med reaktivfärg, som är en färgtyp för cellulosafiber. Affiniteten mellan cellulosafiber och reaktivfärg är relativt låg, vilket innebär att processen kräver hjälpkemikalier som ökar attraktionskraften mellan dessa två. Den hjälpkemikalie som krävs för ökad affinitet är salt, NaCl. Den reaktiva infärgningsprocessen vid uppdragsfärgning kräver stora mängder salt i processvattnet. Detta vatten sprids senare i naturen vilket har en negativ inverkan på miljö och djurliv. Inom textilindustrin utgörs föroreningar till en stor del av just färgning, och det är därför av betydelse att utveckla så hållbara färgningsprocesser som möjligt. Undersökning har gjorts om möjligheten att reducera salt i ett befintligt recept för reaktivfärg, samt av saltets betydelse för slutligt färgresultat. Ett experiment har utförts där fyra olika färgbad har tillblandats och tjugofyra olika saltkoncentrationer har beprövats. Provbitarna utvärderades enligt resultat erhållna vid tvätthärdighetstest och gnidhärdighetstest enligt ISO- standarder. Slutligen gjordes en datoriserad färgmätning på samtliga provbitar vilket gav en mer rättvisande bild huruvida saltet har påverkat färgens svarta nyans. Utifrån erhållna värden gällande försäljning av produkter i H&amp;M-svart, gjordes beräkningen att företagets leverantörer har en årlig saltförbrukning på 45 000 ton. Samma beräkning gjordes med ett saltreducerat recept som har visat på goda färgresultat. Detta nya recept visade på en årlig förbrukning av 27 000 000 kg salt. Om H&amp;M skulle implementera detta i infärgningen av all H&amp;M-svart hos sina leverantörer, skulle en årlig saltbesparing vara 18 000 000 kg. Utifrån erhållna testresultat drogs slutsatsen att saltet endast påverkar affiniteten mellan färg och fiber utan att ha märkvärdig betydelse för färghärdighet (tvätthärdighet samt gnidhärdighet). Dock drogs även slutsatsen att eftersom saltmängden påverkar affiniteten har det även betydelse för grad av intensitet för den svarta nyansen. Ett problem idag är att inköpare och designers är mycket kräsna när det gäller krav på svarta nyanser hos textila produkter. Utbildning och uppmuntrande är av stor vikt för att kunna förändra inställningen hos beslutstagare. Vidare forskning skulle kunna göras kring möjligheter för att använda saltvatten vilket 97 % av jordens vatten består av. På så sätt skulle sötvatten, som idag används vid färgning samt är en bristvara för delar av världens befolkning, besparas från en stor mängd föroreningar. / Program: Textilingenjörsutbildningen

<p>In conventional viscose manufacturing, a large amount of carbondisulfide is consumed. This amount has to be decreased to keep the production cost down and to reduce the environmental impact. The purpose with this work was to show if an enzyme treatment of a dissolving pulp could increase the degree of substitution in the viscose so that the amount of carbon disulfide consumed in the process could be decreased. Previous investigations by Kvarnlöf (2007), Engström et.al. (2006) and Henriksson et.al. (2005) has shown that the reactivity of a dissolving pulp (the cellulose raw material) increased when it was pre-treated with endoglucanase (enzyme). Kvarnlöf (2007) also showed that the amount of carbon disulfide that is needed to produce an ordinary viscose (in this work a more viscous viscose has been investigated) could be reduced with one third because of the enzyme treatment.</p><p> </p><p>In this thesis, viscose has been manufactured in a laboratory where the process has been adapted to look like the industrial as far as possible. Analyses were done on the viscose viscosity and degree of substitution. A reference curve was made with the percentage carbon disulfide load versus the viscose gamma number (degree of substitution). Then it was investigated how an enzyme treatment of the dissolving pulp affected the viscose. After the enzyme treatment, the manufacturing process for viscose was done in the exact same way as when the reference tests were done. The enzyme used in this thesis was Carezyme which contents endoglucanase. Then the results from the analyses of the viscose manufactured from enzyme treated dissolving pulp and the reference curve was compared. A positive result would have been that viscose manufactured with enzyme treatment gets a higher gamma number than viscose, with the same load of carbon disulfide, manufactured in the regular way.</p><p> </p><p>The results showed that the degree of substitution had no effect at all; the viscose that has been manufactured from enzyme treated dissolving pulp resulted in gamma numbers on or very close to the reference curve. The only effect that could be shown was a decrease in viscosity, which unfortunately was an unwanted effect. The enzyme treatment has also hampered the process, where shorter fibres among other things have given poorer dewatering properties. Analyses on the viscose manufactured in the laboratory showed that it didn't have the same characteristics as viscose manufactured in a plant.</p> / <p>I den konventionella tillverkningsprocessen för viskos förbrukas stora mängder koldisulfid. Denna mängd behöver minskas, både för att hålla nere produktionskostnaderna men också för att minska miljöpåverkan. Syftet med arbetet var att undersöka om en enzymbehandling av en dissolvingmassa kunde öka substitutionsgraden så att koldisulfid-förbrukningen skulle kunna minskas. Det har i flera tidigare undersökningar av Kvarnlöf (2007), Engström m.fl. (2006) och Henriksson m.fl. (2005) visats att reaktiviteten hos en dissolvingmassa (råvaran i viskosprocessen) ökar när den förbehandlats med endoglukanas (enzym). Kvarnlöf (2007) visade dessutom att mängden koldisulfid som behövdes för att tillverka spinnviskos (i detta examensarbete har en viskösare viskos undersökts) kunde minskas med en tredjedel tack vare enzymbehandlingen.</p><p> </p><p>I detta examensarbete har viskos tillverkats i laboratoriet där processen har anpassats så att den liknar den industriella så mycket som möjligt. Analyser gjordes på viskosens viskositet och substitutionsgrad. En referenskurva tillverkades där den procentuella koldisulfid-satsningen plottades mot viskosens gammatal (substitutionsgraden). Därefter undersöktes hur en enzymbehandling av dissolvingmassan påverkade den färdiga viskosen. Efter enzymbehandlingen av dissolvingmassan utfördes tillverkningsprocessen precis som vanligt för att man skulle kunna se effekterna av enzymet. Enzymet som användes i arbetet var enzympreparationen Carezyme som innehåller endoglukanas. Sedan jämfördes resultaten från analyserna av viskosen tillverkad från enzymbehandlad dissolvingmassa med referensvärdena. Ett positivt resultat hade varit att enzymbehandlad viskos hade ett högre gammatal än viskos tillverkad på vanligt sätt utan enzymförbehandling men med samma koldisulfidsats.</p><p> </p><p>Resultaten visar att substitutionsgraden inte har påverkats alls, dvs. den viskos som tillverkats från enzymbehandlad dissolvingmassa fick gammatal som låg på eller mycket nära referenskurvan. Den enda effekt av enzymet som kunde visas var en viskositetssänkning, vilket inte var något som eftersträvades. Processen har dessutom försvårats av enzymsteget, där kortare fibrer bl.a. gav sämre avvattningsegenskaper. Viskosanalyser har visat att viskosen som tillverkats på laboratoriet inte har samma egenskaper som viskos tillverkad på fabrik.</p>

<p>The thesis describes an investigation into the interaction between the conducting polymer and cellulosic materials, and the preparation of electroconductive paper. The adsorption behavior of the conducting polymer onto cellulosic materials was characterized. Poly(3,4-ethylenedioxythiophene) doped with poly(4-styrene sulfonate) (PEDOT:PSS) was used as conducting polymer because of its attractive properties in terms of conductivity, water solubility, and environmental stability. The model substrate used for adsorption was microcrystalline cellulose (MCC). Various pH levels and salt concentrations were explored to completely understand the adsorption behavior of PEDOT:PSS. The variation in surface charge characteristics when the pH and salt concentration were changed was monitored by polyelectrolyte titration and zeta potential measurement. The adsorption isotherm showed a broad molecular distribution of the conducting polymer and considerable interaction between the polymer and MCC. As the pH of the solution was increased, the adsorbed amount decreased. With varying salt concentrations, the adsorption passed through a maximum. The extent of deposition of PEDOT:PSS on the surface of cellulosic fibers was investigated using X-ray Photoelectron Spectroscopy (XPS) with a commercial base paper as substrate. XPS analysis of dip-coated paper samples showed PEDOT enrichment on the surface. The degree of washing the dip-coated paper with acidic water did not significantly affect the PEDOT enrichment on the surface.</p><p> </p><p>A base paper was coated with PEDOT:PSS blends to produce electroconductive papers. The bulk conductivities (σ_dc) of the coated papers were measured using a four-probe technique and impedance spectroscopy. One-side and two-side coating gave comparable conductivity levels. Various organic solvents added to the PEDOT:PSS dispersion at different concentrations showed various effects on the bulk conductivity of the coated paper. Blends containing sorbitol and isopropanol did not enhance the bulk conductivity of the coated paper, and at high concentrations these organic solvents lowered the conductivity. Paper samples coated with a PEDOT:PSS blend containing N-methylpyrrolidinone (NMP) and dimethyl sulfoxide (DMSO) exhibited a higher conductivity than when coated with pure PEDOT:PSS, due to conformational changes and their plasticizing effect. The effect of calendering was investigated and only the sample subjected to 174 kN/m line load after coating showed significant conductivity enhancement. The addition of TiO₂ pigment lowered the bulk conductivity of the paper. Contact angle measurements were made to monitor the effect of coating the paper with PEDOT:PSS blends on the hydrophilicity of the paper samples. The amount of PEDOT:PSS deposited in the fiber network was determined using total sulfur analysis. Thus, this study makes use of conventional paper surface treatment as method for achieving bulk conductivity of paper in the semi-conductor range without significantly decreasing the paper strength.</p> / Printed Polymer Electronics

The aim of this study has been to prepare and characterise oil resistant cellulosic materials, ranging from model surfaces to papers and aerogels. The cellulosic materials were made oil resistant by chemical and topographic modifications, based on surface energy, surface roughness and barrier approaches. Detailed wetting studies of the prepared cellulosic materials were made using contact angle measurements and standardised penetration tests with different alkanes and oil mixtures. A significant part of the activities were devoted to the development of model cellulosic surfaces with different degrees of crystalline ordering for the wetting studies. Crystalline cellulose I, II and amorphous cellulose surfaces were prepared by spin-coating of cellulose nanocrystal or microfibrillated cellulose (MFC) dispersions, with Langmuir-Schaefer (LS) films or by a layer-by-layer (LbL) deposition technique. The formation of multilayers consisting of polyethyleneimine (PEI)/anionic MFC or cationic MFC/anionic MFC was further studied and optimized in terms of total layer thickness and adsorbed amount by combining Dual Polarization Interferometry (DPI) or Stagnation Point Adsorption Reflectrometry (SPAR) with a Quartz Crystal Microbalance with Dissipation (QCM-D). The smooth cellulosic surfaces prepared had different molecular and mesostructure properties and different surface energies as shown by X-ray diffraction, Atomic Force Microscopy (AFM) imaging, ellipsometry measurements and contact angle measurements. The cellulose model surfaces were found to be ideal for detailed wetting studies, and after the surface has been coated or covalently modified with various amounts of fluorosurfactants, the fluorinated cellulose films were used to follow the spreading mechanisms of different oil mixtures. The viscosity and surface tension of the oil mixtures, as well as the dispersive surface energy of the cellulose surfaces, were found to be essential parameters governing the spreading kinetics. A strong correlation was found between the surface concentration of fluorine, the dispersive surface energy and the measured contact angle of the oil mixtures. Silicon surfaces possessing structural porous characteristics were fabricated by a plasma etching process. The structured silicon surfaces were coated with sulfate-stabilized cellulose I nanocrystals using the LbL technique. These artificial intrinsically oleophilic cellulose surfaces were made highly oleophobic when coated with a thin layer of fluorinated silanes. By comparison with flat cellulose surfaces, which are oleophilic, it is demonstrated that the surface energy and the surface texture are essential factors preventing oil from spreading on the surface and, thus, inducing the observed macroscopic oleophobic properties. The use of the MFC for surface coating on base papers demonstrated very promising characteristics as packaging materials. Environmental-Scanning Electron Microscopy (E-SEM) micrographs indicated that the MFC layer reduced the sheet porosity, i.e. the dense structure formed by the nanofibers resulted in superior oil barrier properties. Attempts were made to link the procedure for preparation of the MFC dispersions to the resulting microstructure of the coatings, and film porosity and the film moisture content to the resulting permeability properties. Finally, MFC aerogels were successfully prepared by freeze-drying. The surface texture of the porous aerogels was carefully controlled by adjusting the concentration of the MFC dispersion used for the freeze-drying. The different scales of roughness of the MFC aerogels were utilised, together with the very low surface energy created by fluorination of the aerogel, to induce highly oleophobic properties. / QC 20100623

Paper that is subjected to moisture undergoes dimensional changes. It expands during moistening and shrinks during drying. When the paper is under tension between rollers, the effects are complex since shrinkage and expansion are restricted in the width direction. Waves can then appear on the paper web. This can be a problem in heatset web offset printing. The problem is known as waviness or fluting. The printed papers exhibit a wavy shape, which is visually disturbing due to light reflections which create glossy streaks. The aim of the work described in this thesis was to develop a method suitable for studying the moisture- and tension-induced waviness. Experiments were carried out on a laboratory scale to study how such waves develop during moistening and drying. The experimental setup was based on a modified tensile tester. A CCD camera and image analysis based on the STFI-OptiTopo technique was used to characterise the waviness. Moistening and drying were achieved by changing the surrounding air humidity. The method was used to study the effect of moisture uptake by the paper, and to evaluate the effect of tension on the waviness. It was found that increasing moisture resulted in a higher waviness amplitude, but that the web tension controlled the wavelength of the waviness. A high tension gave rise to a shorter wavelength. The measured wavelength was compared with a previously suggested model and the predicted wavelength was about twice as high as the measured wavelength. / When paper becomes damp it can develop waves which can be a problem with heatset web offset printing. Paper with waves may have glossy streaks after printing. Laboratory experiments studied the effect of moisture uptake by the paper. Readings were taken at a range of air humidities. The effect of tension on the waviness was also measured. The waviness was characterised using a charge coupled device (CCD) camera and the STFI-Packforsk OptiTopo technique to analyse the images. When the humidity was increased the amplitude of the waves increased. A high tension resulted in shorter wavelengths. Results from a previous model were used as a comparison.

The thesis describes an investigation into the interaction between the conducting polymer and cellulosic materials, and the preparation of electroconductive paper. The adsorption behavior of the conducting polymer onto cellulosic materials was characterized. Poly(3,4-ethylenedioxythiophene) doped with poly(4-styrene sulfonate) (PEDOT:PSS) was used as conducting polymer because of its attractive properties in terms of conductivity, water solubility, and environmental stability. The model substrate used for adsorption was microcrystalline cellulose (MCC). Various pH levels and salt concentrations were explored to completely understand the adsorption behavior of PEDOT:PSS. The variation in surface charge characteristics when the pH and salt concentration were changed was monitored by polyelectrolyte titration and zeta potential measurement. The adsorption isotherm showed a broad molecular distribution of the conducting polymer and considerable interaction between the polymer and MCC. As the pH of the solution was increased, the adsorbed amount decreased. With varying salt concentrations, the adsorption passed through a maximum. The extent of deposition of PEDOT:PSS on the surface of cellulosic fibers was investigated using X-ray Photoelectron Spectroscopy (XPS) with a commercial base paper as substrate. XPS analysis of dip-coated paper samples showed PEDOT enrichment on the surface. The degree of washing the dip-coated paper with acidic water did not significantly affect the PEDOT enrichment on the surface.   A base paper was coated with PEDOT:PSS blends to produce electroconductive papers. The bulk conductivities (σdc) of the coated papers were measured using a four-probe technique and impedance spectroscopy. One-side and two-side coating gave comparable conductivity levels. Various organic solvents added to the PEDOT:PSS dispersion at different concentrations showed various effects on the bulk conductivity of the coated paper. Blends containing sorbitol and isopropanol did not enhance the bulk conductivity of the coated paper, and at high concentrations these organic solvents lowered the conductivity. Paper samples coated with a PEDOT:PSS blend containing N-methylpyrrolidinone (NMP) and dimethyl sulfoxide (DMSO) exhibited a higher conductivity than when coated with pure PEDOT:PSS, due to conformational changes and their plasticizing effect. The effect of calendering was investigated and only the sample subjected to 174 kN/m line load after coating showed significant conductivity enhancement. The addition of TiO2 pigment lowered the bulk conductivity of the paper. Contact angle measurements were made to monitor the effect of coating the paper with PEDOT:PSS blends on the hydrophilicity of the paper samples. The amount of PEDOT:PSS deposited in the fiber network was determined using total sulfur analysis. Thus, this study makes use of conventional paper surface treatment as method for achieving bulk conductivity of paper in the semi-conductor range without significantly decreasing the paper strength. / Printed Polymer Electronics