In the first part of this work a novel type of low-density, sponge-like material for the separation of mixtures of oil and water has been prepared by vapour deposition of hydrophobic silanes on ultra-porous nanocellulose aerogels. To achieve this, a highly porous (&gt; 99 %) nanocellulose aerogel with high structural flexibility and robustness is first formed by freeze-drying an aqueous dispersion of the nanocellulose. The density, pore size distribution and wetting properties of the aerogel can be tuned by selecting the concentration of the nanocellulose dispersion before freeze-drying. The hydrophobic light-weight aerogels are almost instantly filled with the oil phase when they selectively absorb oil from water, with a capacity to absorb up to 45 times their own weight. The oil can also be drained from the aerogel and the aerogel can then be subjected to a second absorption cycle.In the second part of the work a novel, lightweight and strong porous cellulose material has been prepared by drying aqueous foams stabilized with surface-modified NanoFibrillated Cellulose (NFC). Confocal microscopy and high-speed video imaging show that the long-term stability of the wet foams can be attributed to the octylamine-coated, rod-shaped NFC nanoparticles residing at the air-liquid interface which prevent the air bubbles from collapsing or coalescing. Careful removal of the water yields a porous cellulose-based material with a porosity of 98 % and a density of 30 mg cm-3. These porous cellulose materials have a higher Young’s modulus than other cellulose materials made by freeze drying and a compressive energy absorption of 56 kJ m-3 at 80 % strain. Measurements with an autoporosimeter reveal that most pores are in the range of 300 to 500 μm. / <p>QC 20121107</p>

Lignocellulosic biomasses are an important source of chemical components such as cellulose, lignin and hemicelluloses, and can be used for a variety of purposes in both the pulp and paper and chemical conversion industries. Xylan, the main hemicellulose found in hardwood and grass plants, plays an important role during the pulping/pretreatment process reactions, including those used in 2nd generation bioethanol production. It may also play an important role in the production of certain novel materials. This thesis evaluates the composition of eucalyptus (Eucalyptus urophylla x Eucalyptus grandis), sugarcane bagasse and sugarcane straw, with a specific focus on the structure and properties of xylan. The chemical characterization of biomasses showed that sugarcane bagasse and straw contain larger amounts of extractives, ash and silica than eucalyptus. The large amount of silica leads to an overestimation of the Klason lignin content, if not corrected. By using a complete mass balance approach, sugarcane bagasse and straw were shown to contain smaller amounts of lignin (18.0% and 13.9%, respectively) than previously reported for these raw materials, and certainly a much smaller amount of lignin than was found in eucalyptus (27.4%). The hemicellulose content in sugarcane bagasse (28.7%) and straw (29.8%) was much higher than that in eucalyptus (20.3%). In order to investigate the structure of the xylan in greater detail, it was extracted with dimethyl sulfoxide from holocellulose, obtained by either peracetic acid or sodium chlorite delignification. The structure of the isolated xylans was confirmed by FTIR and 1H NMR analysis. In eucalyptus, the O-acetyl-(4-O-methylglucurono)xylan (MGX) was identified. This had a molar ratio of xylose units to branches of 4-O-methylglucuronic acid of 10:1.1 and a degree of acetylation of 0.39. All 4-O- methylglucuronic acid groups were attached to position O-2 of the xylose units, which had an acetyl group in position O-3. The acetyl groups were distributed in positions O-3 (64%), O-2 (26%) and O-2,3 (10%). The MGX had a molecular weight (Mw) of about 42 kDa. In bagasse and straw, arabinoxylan (AX) was identified. This had a molar ratio of xylose units to arabinosyl substitutions of 10:0.5 for bagasse and 10:0.6 for straw. A degree of acetylation was 0.29 and 0.08 for bagasse and straw, respectively. The arabinose units were attached preferentially to position O-3 in AX. In the xylan from bagasse, the acetyl groups were found in positions O-3 (60%), O-2 (13%) and O-2,3 (27%), while in the xylan from straw, the acetyl groups were distributed between positions O-3 (67%) and O-2 (33%). The AX had a molecular weight (Mw) of about 38 kDa and 30 kDa for bagasse and straw, respectively. The differences in the structure of xylan present in the various biomasses played an important role during hydrothermal pretreatment, which is often used as the first step in 2nd generation ethanol production. The varying amounts of uronic acid and acetyl groups resulted in different starting pH levels of liquor and, thus, affected the chemical transformation in the biomasses in different ways. The hydrothermal pretreatment resulted mostly in the removal and/or transformation of hemicelluloses, but also in the formation of a significant number of pseudo-lignin structures. In addition, in eucalyptus, pseudo-extractives structures were generated. The sugarcane straw showed the highest mass loss during the investigated pretreatment. / <p>QC 20151023</p>

I närvaro av fukt och lokaliserade fältförbättringar kan vattenträd utvecklas inom polymerisoleringen av HV subsea kraftkablar. Vattenträd tenderar att växa obemärligt och försämra isolationsegenskaperna med tiden. Fuktigheten i isoleringen kan effektivt reduceras genom applicering av halvledande svällningsband. Halvledande svullnadstejp ger en unik kombination av elektrisk ledningsförmåga och stor vattenhållande kapacitet. Detta hänför sig till förekomsten av ledande kolsvart (CB) respektive superabsorberande polymer (SAP) partiklar. För att förstå massatransportegenskaperna hos vattenånga inom ett svällande tejp bestämdes transportkoefficienterna. Sorptionen av vattenånga avslöjade koncentrationsberoende transportkoefficienter och en allmän ökning i diffusion och löslighet med ökande vattenaktivitet. Detta tillskrives SAP-komponenternas hygroskopiska och polyelektrolytegenskaper och resulterade i en ökning i diffusiviteten med en faktor 100, vid ökning av relativ fuktighet (RH) från 7 till 65%. Vid högre vattenaktivitet antogs att bildandet av immobila vattenklyftor minskade diffusionen av vattenånga. Flera sorptionslägen föreslogs för sorptionsbeteendet hos tejpen mellan 10 och 80% RH. Införandet av konduktivitet inom bandet minskar potentiella skillnader genom flera kabelskikt och efterföljande fältförbättringar. Konduktivitets- och vattensorptionsegenskaperna hos det halvledande svällningsbandet kan emellertid ändras genom mekaniska kompressioner, som utövas av omgivande kabelkomponenter. Den elektriska resistiviteten hos ett fuktigt svällande tejp under belastning bestämdes därför. På grund av bandets anisotropi utfördes elektriska resistivitetsmätningar över (radiell riktning) och tillsammans med (axiell riktning) tejpen. Bandens radiella och axiella riktningar dominerades av närvaron av SAP och CB. En signifikant minskning av bandets radiella resistivitet observerades när fuktigheten ökades från 40% till 60% RH. Resistiviteten minskade med en faktor 100. Ingen signifikant effekt av kompression observerades, men tejpen visade en minskande trend i resistivitet med ökande kompression. Vid 60% RH-radiell resistivitet närmade sig axiell resistivitet, och påverkan av SAP sänks. Den axiella resistiviteten var omkring 18 Ωcm. Tejpens axiella resistivitet påverkades mindre av fuktighet och kompression än den radiella resistiviteten. Åldrande avslöjar försämring av svullnadshöjd, men hade ingen inverkan på bandresistivitet. / In presence of moisture and localized field enhancements water trees might develop within the polymeric insulation of HV subsea power cables. Water trees tend to grow unnoticeable and deteriorate the insulation properties with time. The humidity within the insulation can efficiently be reduced through the application of semiconducting swelling tapes. Semi conducting swelling tapes provide a unique combination of electrical conductivity and a large water retention capacity. This is attributed to the presence of conductive carbon black (CB) and superabsorbent polymer (SAP) particles, respectively. To understand the mass transport properties of water vapor within a swelling tape, transport coefficients were determined. The sorption of water vapor revealed concentration dependent transport coefficients and a general increase in diffusion and solubility with increasing water activity. This was attributed to the hygroscopic and polyelectrolyte properties of the SAP components and resulted in an increase in diffusivity by a factor of 100, when increasing the relative humidity (RH) from 7 to 65 %. At higher water activity, it was assumed that the formation of immobile water clusters reduced the diffusion of water vapor. Several sorption modes were suggested for the sorption behaviour of the tape between 10 to 80 % RH. The introduction of conductivity within the tape reduces potential differences throughout several cable layers and subsequent field enhancements. However, conductivity and water sorption properties of the semi-conductive swelling tape can be altered by mechanical compressions, exerted by surrounding cable components. The electrical resistivity of a humid swelling tape under load was therefore determined. Due to the anisotropy of the tape, electrical resistivity measurements were performed across (radial direction) and along with (axial direction) the tape. The radial and axial directions of the tape were dominated by the presence of SAPs and CBs, respectively. A significant reduction in radial resistivity of the tape was observed when increasing the humidity from 40 % to 60 % RH. The resistivity decreased by a factor of 100. No significant effect of compression was observed, but the tape showed a decreasing trend in resistivity with increasing compression. At 60 % RH radial resistivity approached axial resistivity, and the influence of SAPs is reduced. The axial resistivity was around 18 Ωcm. The axial resistivity of the tape was less affected by humidity and compression than the radial resistivity. Ageing reveal deterioration of swelling height, but had no influence on tape resistivity.

The adsorption of polyelectrolytes, both as monolayers and as multilayers, was investigated as an easy and non-expensive way of producing lignocellulosic fibrous materials with enhanced mechanical properties. In the first part of the work described in this thesis, the adsorption of a polyelectrolyte monolayer onto the surface of unbleached and unbeaten kraft pulp fibres with different kappa numbers was investigated. Adsorption isotherms were obtained in order to determine the amounts of polymer that could be adsorbed by the different pulps. Handsheets were made from the treated fibres and the mechanical properties were studied. The results showed that the use of only 2 mg/g of a polymeric amine such as polyallylamine or polyvinylamine could under certain conditions increase the tensile strength index by up to 50 %. In a second investigation, the Layer-by-Layer deposition technique was used to build up polyelectrolyte multilayers on the surfaces of bleached kraft pulp fibres. Two systems were studied and the presence of added salt in the systems was also investigated. The results showed that the system composed of polyallylamine hydrochloride and hyaluronic acid provided a dramatic increase in both strength (from 20 Nm/g to 70 Nm/g) and strain at break (from 2.0 % to 6.5 %) with only five deposited bilayers. Such a stretchability could make this material very suitable for 3D-forming of packaging materials. The behaviour of this polyallylamine/hyaluronic acid system was then studied from a more fundamental point of view in a third study in order to determine the mechanisms on the nano-scale behind the large improvements observed on the macroscopic paper scale. A quartz crystal microbalance equipment was used to study the adsorption onto model surfaces and show the superlinear trend of the build-up. Atomic force microscopy was also used to study the structural changes occurring upon adsorption of each polymeric layer as well as the adhesive properties of the system. / <p>QC 20121204</p>

The viscoelastic behavior of a delignified birch and poly(methyl methacrylate) (PMMA) composite was investigated, in an effort to learn more about the mechanical properties of transparent wood-polymer biocomposites. Tensile creep tests with constant load were performed for native wood, non-delignified, and delignified wood-polymer composites. Both longitudinal (fibre direction) and transverse (perpendicular to fibre direction) loading directions were tested. Full-field strain analysis was performed using a digital image correlation (DIC) technique. The time-dependence of transverse strain, longitudinal strain, elastic modulus, and Poisson ratio was reported. The creep strain in the transverse fibre direction increased more than two times the longitudinal creep strain. The polymer phase in the wood-polymer biocomposites reduces the relative creep strain compared to native wood. A Kelvin model was used to determine the creep properties of the nominal strain data. Model parameters were obtained for the materials and the model shows a good fit for most materials. However, the Kelvin model parameters were not validated against other tests and are only used here for material comparison. / Det viskoelastiska beteendet hos en delignifierad björk och poly(metylmetakrylat) (PMMA) komposit undersöktes i ett försök att lära sig mer om de mekaniska egenskaperna hos transparenta träpolymerkompositer. Dragkryptester med konstant belastning utfördes för rent trä, icke-delignifierat och delignifierat träpolymerkompositer. Belastning längsgående och tvärgående fiberriktning testades. Töjningsfältsanalyser utfördes med användning av en digital bildkorrelationsteknik (DIC). Tidsberoendet av transversell töjning, longitudinell töjning, elasticitetsmodul och tvärkontraktion rapporterades. Kryptöjningen i den tvärgående fiberriktningen ökade mer än två gånger den längsgående kryptöjningen. Polymerfasen i träpolymerbiokompositerna minskar den relativa kryptöjningen jämfört med rent trä. En Kelvin-modell användes för att bestämma krypegenskaperna för nominell töjningsdata. Modellparametrar erhölls för materialen och modellen visar en god anpassning till de flesta material. Kelvin-modellens parametrar validerades dock inte mot andra tester och används endast här för materialjämförelse.

During this master thesis project, various polymer materials have been studied in relation to additive manufacturing. Additive manufacturing is a 3D printing process that has facilitated the productivity of the company, Volvo Cars. The printing process is based on a design conceived from CAD software. The final design is sent in digital form to the printer from which the prototype is built, layer by layer, until the finished product is finished. This thesis project analyzed which polymers would work the best in Volvo’s car industry as to durability and sustainability. A limited number of polymers were chosen for investigation, some also with various additives to change the microstructure and properties. The tensile strength of the polymers was tested, yielding their Young´s modulus. Tests were also performed to measure the wear resistance of the samples. The design of the samples was decided to be a circular disk. The reason behind was that the samples should not be too thin or have a too complicated shape, the inner structure being solid. The primary data were the possible changes in thickness. These samples were afterwards examined under a stereo microscope in order to obtain a 2D image of how the surface had changed. From all the polymers investigated, the tensile tests showed that PA12 CF(polyamide 12 carbon fiber) had the best strength as it contains carbon fibres which stabilizes the material. However, as for wear resistance the polymers PC (polycarbonate) and TPU( thermoplastic polyurethane) could handle more punches before they fractured. PC has the advantages of being very strong, due to very strong bonds between the atoms within the polymers chains, and at the same time constituting a very flexible material. TPU is also a very strong and flexible material, and it has the extra advantage of being suitable for large components. Considering these aspects, these three materials are selected as efficient and suitable for making mechanical components. As a result from this very investigation, they are recommended for making prototypes or components that have good strength and wear resistance.

Cellulose-based materials draw their good mechanical properties from the cellu-lose crystal. Improved understanding of crystal properties could lead to a wider range of applications for cellulose-based materials, Cellulose crystals show high axial Youngs modulus. Cellulose can attain several allomorphic forms which show unique structural arrangements in terms of both intra-molecular and inter-molecular bonding, as well as unit cell parameters and chain packing. Although several studies have confirmed that mechanical tensile properties of cellulose differ between different allomorphic forms, few reports have investigated the deformation mechanisms explaining the differences.In the first part of this thesis, the tensile elastic Youngs modulus of cellulose allo-morphs Iβ, II and III I were calculated under uniform conditions using Molecular Dynamics simulation techniques. As expected, a difference in modulus valuesc ould be observed, and the cooperative nature of energy contributions to crys-tal modulus is apparent. The allomorphs also show large differences in terms of how contributions to elastic energy are distributed between covalent bonds,angles, dihedrals, electrostatic forces, dispersion and steric forces.In the second part of this thesis, the cellulose Iβ and II allomorphs were sub-jected to a more detailed structural study. The purpose was to clarify how the deformation of the central glucosidic linkage between the monomer units depends on the hydrogen-bonding structures. This was carried out by studying simulated vibrational spectra and local deformations in the crystals.The results presented in this thesis confirm the differences in the tensile elastic properties of these cellulose allomorphs. These differences can in part be explained by the different intra-molecular hydrogen bonding patterns between allomorphs. Deformation mechanisms are discussed. The results are in supportof the so called ”leverage effect” proposed in the literature. The present analysis shows significant differences in details of deformation mechanisms compared with previous simpler analyses. / <p>QC 20150518</p>

Microspheres are spherically shaped particles within the size range of 1-1000 μm in diameter. Due to the their small size and round shape, microspheres show many advantages in various applications such as pharmaceuticals, composites and coatings. The microspheres can be customized to fit a specific application and are manufactured in various forms such as solid, hollow and encapsulating. Encapsulating cellulose microspheres have been produced in this project by the emulsionsolvent evaporation technique. The purpose of this study was to further investigate the possibility of producing encapsulating microspheres with a size range of 10-50 μm that will have a high encapsulation. A second purpose of this study was optimizing the emulsifier system for the preparation of these spheres. This has been accomplished by varying several process parameters such as type of emulsifiers and solvents to study the effect on morphology and encapsulation efficiency. The analyses of the spheres were performed with optical microscopy, thermal gravimetric analyzer (TGA) and scanning electron microscopy (SEM). The emulsifier type and concentration affected the encapsulation and size distribution but had no direct effect on the internal and external structure, which was multi-cellular and porous, respectively. The highest encapsulation in relation to average size was obtained with 0.1 v/v- % of the emulsifier mixture Emulsifier 1 (E1)/Emulsifier 2 (E2) (70/30 %). The solvent used to dissolve the polymer had a direct effect on encapsulation, a combination of Solvent 2 (S2) and Solvent 1 (S1) proved best for the three tested cellulose derivatives with low, medium and high number average molecular weight. The solvent also had an effect on the internal structure of the microspheres, becoming more core-shell when using the S1/S2 combination.

In this project, different MUF resins were synthesized with varying melamine content, F/NH2 molar ratio, number of addition steps and with varying addition order of the reactants during synthesis. Further, it was investigated how these synthesis parameters influenced resin properties including storage stability and free formaldehyde content. Additionally, NMR spectroscopy was used in order to study the resulting chemical structure of the resins and their molecular size and molecular size distribution were examined by SEC and MALDI-TOF-MS. The curing kinetics of the resins were studied by Raman spectroscopy. From the resins, cured glue joints were prepared and the mechanical properties and water resistance of these were tested through tensile shear testing after different pretreatments of the glue joints. It was confirmed that synthesis under both alkaline and acidic conditions resulted in a higher amount of ether bridges in the resin in comparison to synthesis under acidic conditions. Furthermore, a high melamine content and fewer urea additions resulted in resins with a higher amount of methylol groups and less substituted functional groups. Comparatively, when the F/NH2 molar ratio was increased or when formalin was added in two steps, a resin with higher amount of substituted groups and structures of higher degree of condensation was obtained. From the synthesis procedure it was concluded that a long condensation time at alkaline conditions was the most efficient way to achieve a low free formaldehyde content, while a high F/NH2 molar ratio resulted in the highest amount of free formaldehyde. Furthermore, a high amount of flexible ether bridges, low amount of methylol groups, low melamine content, high F/NH2 molar ratio and a high degree of branched chains seem to be important structural parameters for achieving resins with a long shelf life. Additionally, from the SEC-analysis it was found that the resins had an average molecular weight (Mn) between 1000-1600 g/mol and a broad molecular weight distribution, which were further verified by MALDI-TOF-MS. The resins with a high melamine content had shorter chains, and the molecular weight distribution was most significantly increased when the number of addition steps were changed. Through analysis of the curing process it was found that a higher hardener-to-resin mixing ratio resulted in a faster curing process and a higher final degree of cross-linking. Additionally, it appeared as the reaction of methylol groups was less pH-dependent than the reactions of ether bridges and methylene bridges, which both were favored at lower pH. From the kinetic profiles it was observed that the resin with a higher amount of ether bridges and lower amount of methylol groups had a more prolonged curing process. Furthermore, the mechanical testing of the resulting cured glue joints showed no significant difference in tensile strength between the resins when tested in the dry state. However, a reduced tensile strength were observed for the resin with higher melamine content when tested in the wet state, hence indicating that the increased melamine content used in this project is not enough in order to significantly improve the mechanical properties or water resistance of the cured glue joint observable with the used method. / I detta arbete har MUF-hartser syntetiserats med varierande melaminhalt, F/NH2 molkvot och satsningsförfarande av reaktanter under syntes. Vidare undersöktes det hur dessa syntesparametrar påverkar hartsernas egenskaper så som lagringsstabilitet och fri formaldehyd innehåll. Dessutom tillämpades NMR spektroskopi för att studera hartsernas kemiska struktur medan SEC och MALDITOF-MS analyser utfördes för att få en uppfattning om hartsernas molekylvikt samt molekylviktsfördelning. Vidare analyserades hartsernas härdningskinetik med Raman spektroskopi. Från de syntetiserade hartserna förbereddes härdade limfogar vars mekaniska egenskaper och vattenbeständighet studerades genom dragprovstestning efter olika förbehandlingar av fogarna. Från hartsernas kemiska struktur kunde det bekräftas att då syntes utfördes under både basiska och sura betingelser erhölls en högre mängd eterbryggor i hartserna i jämförelse med syntes under endast sura betingelser. Vidare konstaterades det att hartserna med högre melaminhalt samt hartset som tillverkades med färre ureasatsningar bestod av en högre mängd metylolgrupper och en mindre andel substituerade grupper på melamin och urea. Jämförelsevis resulterade en högre F/NH2 molkvot samt två formalinsatsningar under syntes i en större mängd substituerade grupper och i en högre andel större molekylstrukturer. Från den erhållna mängden fri formaldehyd i hartsen kunde det konstateras att en lång kondensationstid under basiska betingelser var det mest effektiva sättet att sänka detta värde. Jämförelsevis hade hartserna med hög F/NH2 molkvot det högsta innehållet av fri formaldehyd. Då hartsernas lagringstabilitet undersöktes visade det sig att en hög andel flexibla eterbryggor, en låg andel metylolgrupper, en låg melaminhalt, en hög F/NH2 molkvot och en hög andel grenade kedjor resulterade i förbättrad lagringsbeständighet. Från SEC-analysen erhölls hartsernas molekylvikter (Mn) i området 1000-1600 g/mol samt en bred molekylviktsfördelning. Resultaten var vidare bekräftade med MALDI-TOF-MS. Det observerades att hartserna med högre melaminhalt hade lägre molekylvikt samt att hartserna tillverkade med olika antal satsningar hade högst dispersitet. Då hartsernas härdningsförlopp studerades kunde det konstateras att ett högre bladningsförhållande av härdare/harts resulterade i en snabbare härdningsprocess samt i en större andel tvärbindningar i systemet. Dessutom visade det sig att reaktionen med metylolgrupper är mindre pH-beroende än omlagringen av eterbryggor och bildandet av metylenbryggor. De två sistnämda reaktionerna gynnas vid lägre pH. Då de kinetiska profilerna av hartserna jämfördes noterades det att hartset med en högre mängd eterbryggor och en lägre andel metylolgrupper hade en långsammare härdningsprocess. Från resultaten av de mekaniska analyserna på de härdade limfogarna kunde det konstateras att ingen signifikant skillnad i dragstyrka fanns mellan de olika fogarna då de testades i torrt tillstånd. Däremot observerades en minskad dragstyrka för hartset med högre melaminhalt då fogarna undersöktes i vått tillstånd. Detta visar på att den ökade melaminhalten som används i hartserna i detta projekt inte är tillräcklig för att resultera i en, med den använda metoden observerbar, förbättrad dragstyrka eller vattenbeständighet hos den motsvarande härdade limfogen.

Det här projektet har utförts på Scania och är en förstudie till en standardbeskrivning där olika bindemedel i ledningsnät studerats för att kunna användas i olika miljöer i lastbilen så som hytt chassi och drivlina. Olika krav som temperatur, kemikaliebeständighet och fuktresistans ställs för de olika miljöerna. Bindemedlet ska hålla kablarna på plast i en skyddsslang och samtidigt fungera som tätning. De limtyper som har studerats i den här rapporten är ett epoxilim, ett epoxy-cyanoacrylate hybrid lim, ett smältlim av polyamid och två siliconlim. De har limmats på några av de platser som används i lastbilen och sedan utsatts för dragtester, kemikalietester, åldring- och klimattest. Inget av de testade limmerna klarade alla testerna men den limgrupp som klarade testen bäst var de av silicon. / This project has been performed at Scania and it is a pre-study for a standard description of binders in cables harness in different environments in the truck. The different environmental zones are the cab, chassis and power train. Different zones in the truck have different requirements such as temperature, chemicals and moister resistance. The function of the binder is to glue cables into a protective hose of plastic and also act as a seal. The different types of adhesives that have been study in this report is epoxy adhesive, epoxy-hybrid cyanoacrylate adhesive, hot melt by polyamide and two types of silicon glue. They have been glued to some of the different plastics that the cables are made of in the truck and then they have been exposed to tensile tests, chemical tests, aging and climate tests. None of the tested adhesives passed all the tests, but silicon glue passed most of the tests.