ZnO nanoparticles in the size range 2.5–7 nm have been synthesised by a wet chemical method where ZnO particles were grown in basic zinc acetate solution. The optical band gap increases when the size of the particles decreases. An empirical relation between the optical band gap given from absorption measurements, and particle size given from XRD measurements has been developed and compared to other similar relations found in the literature.    Time resolved UV-Vis spectroscopy has been used to follow the growth of particles in situ in solution. The data show that the growth mechanism not can be described by a simple Oswald ripening approach and nor by an exclusive agglomeration of smaller clusters into larger particles. The growth mechanism is more likely a combination of the proposed reaction themes. The data also reveal that particle formation do not demand a heating step for formation of the commonly assumed initial cluster Zn4O(CH3COO)6.    Steady state fluorescence has been studied as a function of particle size during growth in solution. These measurements confirm what is found in the literature in that the visible fluorescence is shifted to longer wavelengths and loses in intensity as the particles grow. Some picosecond spectroscopy has also been done where the UV fluorescence has been investigated. From these measurements it is apparent that the lifetime of the fluorescence increases with particle size.     The phonon spectrum of ZnO has been studied with Raman spectroscopy for a number of different particle sizes. From these measurements it is clear that there is a strong quenching of the phonons due to confinement for the small particles, and the only clearly observed vibration is one at 436 cm-1 which intensity strongly increases with particle size.

III-Nitride semiconductors are very promising in both electronics and optical devices. The ability of the III-Nitride semiconductors as light emitters to span the electromagnetic spectrum from deep ultraviolet light, through the entire visible region, and into the infrared part of the spectrum, is a very important feature, making this material very important in the field of light emitting devices. In fact, the blue emission from Indium Gallium Nitride (InGaN), which was awarded the 2014 Nobel Prize in Physics, is the basis of the common and important white light emitting diode (LED). Quantum dots (QDs) have properties that make them very interesting for light emitting devices for a range of different applications, such as the possibility of increasing device efficiency. The spectrally well-defined emission from QDs also allows accurate color reproduction and high-performance communication devices. The small size of QDs, combined with selective area growth allows for an improved display resolution. By control of the polarization direction of QDs, they can be used in more efficient displays as well as in traditional communication devices. The possibility of sending out entangled photon pairs is another QD property of importance for quantum key distribution used for secure communication. QDs can hold different exciton complexes, such as the neutral single exciton, consisting of one electron and one hole, and the biexciton, consisting of two excitons. The integrated PL intensity of the biexciton exhibits a quadratic dependence with respect to the excitation power, as compared to the linear power dependence of the neutral single exciton. The lifetime of the neutral exciton is 880 ps, whereas the biexciton, consisting of twice the number of charge carriers and lacks a dark state, has a considerably shorter lifetime of only 500 ps. The ratio of the lifetimes is an indication that the size of the QD is in the order of the exciton Bohr radius of the InGaN crystal making up these QDs in the InGaN QW. A large part of the studies of this thesis has been focused on InGaN QDs on top of hexagonal Gallium Nitride (GaN) pyramids, selectively grown by Metal Organic Chemical Vapor Deposition (MOCVD). On top of the GaN pyramids, an InGaN layer and a GaN capping layer were grown. From structural and optical investigations, InGaN QDs have been characterized as growing on (0001) facets on truncated GaN pyramids. These QDs exhibit both narrow photoluminescence linewidths and are linearly polarized in directions following the symmetry of the pyramids. In this work, the neutral single exciton, and the more rare negatively charged exciton, have been investigated. At low excitation power, the integrated intensity of the PL peak of the neutral exciton increases linearly with the excitation power. The negatively charged exciton, on the other hand, exhibits a quadratic power dependence, just like that of the biexciton. Upon increasing the temperature, the power dependence of the negatively charged exciton changes to linear, just like the neutral exciton. This change in power dependence is explained in terms of electrons in potential traps close to the QD escaping by thermal excitation, leading to a surplus of electrons in the vicinity of the QD. Consequently, only a single exciton needs to be created by photoexcitation in order to form a negatively charged exciton, while the extra electron is supplied to the QD by thermal excitation. Upon a close inspection of the PL of the neutral exciton, a splitting of the peak of just below 0.4 meV is revealed. There is an observed competition in the integrated intensity between these two peaks, similar to that between an exciton and a biexciton. The high energy peak of this split exciton emission is explained in terms of a remotely charged exciton. This exciton state consists of a neutral single exciton in the QD with an extra electron or hole in close vicinity of the QD, which screens the built-in field in the QD. The InGaN QDs are very small; estimated to be on the order of the exciton Bohr radius of the InGaN crystal, or even smaller. The lifetimes of the neutral exciton and the negatively charged exciton are approximately 320 ps and 130 ps, respectively. The ratio of the lifetimes supports the claim of the QD size being on the order of the exciton Bohr radius or smaller, as is further supported by power dependence results. Under the assumption of a spherical QD, theoretical calculations predict an emission energy shift of 0.7 meV, for a peak at 3.09 eV, due to the built-in field for a QD with a diameter of 1.3 nm, in agreement with the experimental observations. Studying the InGaN QD PL from neutral and charged excitons at elevated temperatures (4 K to 166 K) has revealed that the QDs are surrounded by potential fluctuations that trap charge carriers with an energy of around 20 meV, to be compared with the exciton trapping energy in the QDs of approximately 50 meV. The confinement of electrons close to the QD is predicted to be smaller than for holes, which accounts for the negative charge of the charged exciton, and for the higher probability of capturing free electrons. We have estimated the lifetimes of free electrons and holes in the GaN barrier to be 45 ps and 60 ps, in consistence with excitons forming quickly in the barrier upon photoexcitation and that free electrons and holes get trapped quickly in local potential traps close to the QDs. This analysis also indicates that there is a probability of 35 % to have an electron in the QD between the photoexcitation pulses, in agreement with a lower than quadratic power dependence of the negatively charged exciton. InN is an attractive material due to its infrared emission, for applications such as light emitters for communication purposes, but it is more difficult to grow with high quality and low doping concentration as compared to GaN. QDs with a higher In-composition or even pure InN is an interesting prospect as being a route towards increased quantum confinement and room temperature device operation. For all optical devices, p-type doping is needed. Even nominally undoped InN samples tend to be heavily n-type doped, causing problems to make pn-junctions as needed for LEDs. In our work, we present Mg-doped p-type InN films, which when further increasing the Mg-concentration revert to n-type conductivity. We have focused on the effect of the Mg-doping on the light emission properties of these films. The low Mg doped InN film is inhomogeneous and is observed to contain areas with n-type conductivity, so called n-type pockets in the otherwise p-type InN film. A higher concentration of Mg results in a higher crystalline quality and the disappearance of the n-type pockets. The high crystalline quality has enabled us to determine the binding energy of the Mg dopants to 64 meV. Upon further increase of the Mg concentration, the film reverts to ntype conductivity. The highly Mg doped sample also exhibits a red-shifted emission with features that are interpreted as originating from Zinc-Blende inclusions in the Wurtzite InN crystal, acting as quantum wells. The Mg doping is an important factor in controlling the conductivity of InN, as well as its light emission properties, and ultimately construct InN-based devices. In summary, in this thesis, both pyramidal InGaN QDs and InGaN QDs in a QW have been investigated. Novel discoveries of exciton complexes in these QD systems have been reported. Knowledge has also been gained about the challenging material InN, including a study of the effect of the Mg-doping concentration on the semiconductor crystalline quality and its light emission properties. The outcome of this thesis enriches the knowledge of the III-Nitride semiconductor community, with the long-term objective to improve the device performance of III-Nitride based light emitting devices.

The thesis focuses on exploring the sub-grain structure in stainless steel 316L prepared by additive manufacturing (AM). Two powder-bed based AM methods are involved: selective laser melting (SLM) and electron beam melting (EBM). It is already known that AM 316L has heterogeneous property and hierarchy structure: micro-sized melt pools, micro-sized grains, nano-sized sub-grain structure and nano-sized inclusions. Yet, the relation among these structures and their influence on mechanical properties have not been clearly revealed so far. Melt pool boundaries having lower amount of sub-grain segregated network structures (Cellular structure) are weaker compared to the base material. Compared with cell boundaries, grain boundaries have less influence on strength but are still important for ductility. Cell boundaries strengthen the material without losing ductility as revealed by mechanical tests. Cellular structure can be continuous across the melt pool boundaries, low angle sub-grain boundaries, but not grain boundaries. Based on the above understanding, AM process parameters were adjusted to achieve customized mechanical properties. Comprehensive characterization were carried out to investigate the density, composition, microstructure, phase, magnetic permeability, tensile property, Charpy impact property, and fatigue property of both SLM and EBM SS316L at room temperature and at elevated temperatures (250°C and 400°C). In general, SLM SS316L has better strength while EBM SS316L has better ductility due to the different process conditions. Improved cell connection between melt pools were achieved by rotating 45° scanning direction between each layer compared to rotating 90°. Superior mechanical properties (yield strength 552 MPa and elongation 83%) were achieved in SLM SS316L fabricated with 20 µm layer thickness and tested in the building direction. Y2O3 added oxide dispersed strengthening steel (ODSS) were also prepared by SLM to further improve its performance at elevated temperatures. Slightly improved strength and ductility (yield strength 574 MPa and elongation 90%) were obtained on 0.3%Y2O3-ODSS with evenly dispersed nanoparticles (20 nm). The strength drops slightly  but ductility drops dramatically at elevated temperatures. Fractographic analysis results revealed that the coalescence of nano-voids is hindered at room temperature but not at elevated temperatures. The achieved promising properties in large AM specimens assure its potential application in nuclear fusion. For the first time, ITER first wall panel parts with complex inner pipe structure were successfully fabricated by both SLM and EBM which gives great confidence to application of AM in nuclear industry. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Manuscript. Paper 5: Manuscript.</p>

There are multiple applications for polymers: our bodies are built of them, plastic bags and boxes used for storage are composed of them, as are the shells for electronics, TVs, computers, clothes etc. Many polymers are cheap, and easy to manufacture and process which make them suitable for disposable systems. The choice of polymer to construct an object will therefore highly influence the properties of the object itself. The focus of this thesis is the application of commonly used polymers to solve some challenges regarding integration of electrodes in electrokinetic devices and 3D printing. The first part of this thesis regards electrokinetic systems and the electrodes’ impact on the system. Electrokinetic systems require Faradaic (electrochemical) reactions at the electrodes to maintain an electric field in an electrolyte. The electrochemical reactions at the electrodes allow electron-to-ion transduction at the electrode-electrolyte interface, necessary to drive a current at the applied potential through the system, which thereby either cause flow (electroosmosis) or separation (electrophoresis). These electrochemical reactions at the electrodes, such as water electrolysis, are usually problematic in analytical systems and systems applied in biology. One solution to reduce the impact of water electrolysis is by replacing metal electrodes with electrochemically active polymers, e.g. poly(3,4-ethylenedioxythiophene) (PEDOT). Paper 1 demonstrates that PEDOT electrodes can replace platinum electrodes in a gel electrophoretic setup. Paper 2 reports an all-plastic, planar, flexible electroosmotic pump which continuously transports water from one side to the other using potentials as low as 0.3 V. This electroosmotic pump was further developed in paper 3, where it was made into a compact and modular setup, compatible with commercial microfluidic devices. We demonstrated that the pump could maintain an alternating flow for at least 96 h, with a sufficient flow of cell medium to keep cells alive for the same period of time. The second part of the thesis describes the use of 3D printers for manufacturing prototypes and the material requirements for 3D printing. Protruding and over-hanging structures are more challenging to print using a 3D printer and usually require supporting material during the printing process. In paper 4, we showed that polyethylene glycol (PEG), in combination with a carbonate-based plasticizer, functions well as a 3D printable sacrificial template material. PEG2000 with between 20 and 30 wt% dimethyl carbonate or propylene carbonate have good shear-thinning rheology, mechanical and chemical stability, and water solubility, which are advantageous for a supporting material used in 3D printing. The advances presented in this thesis have solved some of the challenges regarding electrokinetic systems and prototype manufacturing. Hopefully this will contribute to the development of robust, disposable, low-cost, and autonomous electrokinetic devices. / Polymera material finns överallt omkring oss; våra kroppar är uppbyggda av dem,plastpåsarna och burkarna vi förvarar vår mat av består av dem, våra kläder och andra tingsom finns i vår vardag är uppbyggda av olika typer av polymerer. En polymer är uppbyggd aven repetitiv sekvens av identiska grupper, de kan liknas vid en mönsterrapport vilken är denminsta del som man behöver repetera för att få mönstret. Beroende på hur rapporten ser ut såförändras utseendet av mönstret. Hos en polymer påverkar sammansättningen av denrepetitiva gruppen (rapporten) egenskaperna av materialet och polymerer kan vara allt frånhårda och robusta, till flexibla och elektriskt ledande. Arbetet som presenteras i den häravhandlingen berör hur funktionen av olika system påverkas av att man använder sig avpolymerer istället för konventionella material. Första delen av avhandlingen handlar om integrering av elektronik i system som innehållervätska. När vätskor, laddade partiklar, molekyler och joner rör på sig på grund av ett yttreelektriskt fält, så kallas detta för elektrokinetik. Detta kan användas för att pumpa vätska ikanaler som är mindre än 0.2 mm, genom så kallad elektroosmos, samtidigt kommermolekyler med olika laddning att börja separera, så kallad elektrofores. Elektroosmos användsinom t.ex. analytisk kemi för injektion och transport av vätskor. Elektrofores används inombl.a. rättsvetenskap och molekylärbiologi för att separera makromolekyler, så som DNA ochproteiner, med avseende på deras storlek och laddning. I dessa system använder man sig oftastav metallelektroder. När en spänning läggs till ett par metallelektroder som är i kontakt med vatten kommer denhuvudsakliga reaktionen att vara spjälkning av vatten, så kallad vattenelektrolys. Spjälkningav vatten innebär att det bildas vät-och syrgas samt att pH börjar ändras. Gaserna som bildaskan bryta kopplingen mellan elektroderna och därmed stoppar strömmen, så som sker när mandrar ut sladden för t.ex. en elvisp. Förändringar i pH kan t.ex. påverka biologiska provernegativt, så som proteiners funktion och kan leda till celldöd, men kan också minska flödenaen elektroosmotisk pump kan generera. Det finns flera olika sätt hur man kan hanteravattenelektrolys i system med metallelektroder, så som användning av en pH-buffer. Arbetet iden här avhandlingen visar vad som händer om man ersätter metallelektroder med elektrisktledande plastelektroder. I detta fall har metallelektroderna ersatts av den elektriskt ledandepolymeren PEDOT vilket resulterar i att , där man istället för generera gas och pHviförändringar, så förflyttar man joner mellan elektroden och omgivande lösning. Ledandepolymerer är billiga och enkla att tillverka vilket gör dem lämpliga för engångssystem. förändringar, så förflyttar man joner mellan elektroden och omgivande lösning. Ledandepolymerer är billiga och enkla att tillverka vilket gör dem lämpliga för engångssystem.I den här avhandlingen visas följande exempel där metallelektroder ersatts av ledandeplastelektroder: Gelelektrofores (separation av proteiner i en gel), (se papper 1), tyg som kanpumpa vatten (plan elektroosmotisk pump, se papper 2) och en kompakt pump som inte ärstörre än ett kaffemått, som enkelt kan kopplas till befintliga sprutkopplingar och som kananvändas för att kontrollera flödet över t.ex. celler (se papper 3). Andra delen av avhandlingen handlar om 3D skrivare och hur materialval påverkarutskriften och designen. 3D skrivare är ett bra alternativ för att snabbt och billigt kunnaproducera prototyper och funktionella individanpassade objekt i varierande storlekar.3D skrivare kan beskrivas som en avancerad spritsmaskin där material läggs lager på lager föratt bygga upp det slutgiltiga objektet utifrån en datorgenererade 3D model. Detta förändrarhelt hur man designar objekt och vilka möjliga strukturer och material man kan använda sigav jämfört än då man till exempel använder sig av svarv eller fräs för tillverkning. Det finnsflera olika typer av 3D skrivare, t.ex. smältplastskrivare (den typ som man kan se i flertaletaffärer idag) och den variant som använts i den här avhandlingen, en sprutbaserad. Ensprutbaserad 3D skrivare kan hantera många olika typer av material så länge dessa kan fyllas ien spruta och tryckas ut genom en nål. Det färdiga resultat kan därmed bli mycket olikaberoende på vilka material som använts. Överhängande och utstickande strukturer kan vara komplicerade att skriva ut med en3D skrivare. Utskrift av dessa strukturer kan underlättas genom att man skriver ut en temporärstruktur i ett annat material, ett offermaterial. Offermaterialet fungerar som en mall eller stödtill det slutgiltiga objektet och tas bort (offras) när övriga delar av objektet är klara. I den häravhandlingen beskrivs hur ett offermaterial baserat på polyetylen glykol (PEG, vanligtförekommande i t.ex. schampo och läkemedel) och en mjukgörare kan anpassas för attfungera tillsammans med en sprutbaserad 3D skrivare (se papper 4) för att skriva ut strukturerfrån 0,2 mm och uppåt. Arbetet i den här avhandlingen visar användningen av den ledande polymeren PEDOT i ettelektroforessystem och en elektroosmotisk pump. Detta kan förhoppningsvis underlättautvecklingen av dessa system till att bli mindre, smidigare, snabbare och billigare. Den andradelen presenterar ett vattenlösligt, PEG-baserat material som kan användas som stöd till andramaterial i sprutbaserade 3D utskrifter för att underlätta tillverkningen av 3D utskrivna objekt.

The state-of-the-art tools for machining metals are primarily based on a metal-ceramic composite(WC-Co) coated with different combinations of carbide, nitride and oxide coatings. Combinations of these coating materials are optimized to withstand specific wear conditions. Oxide coatings are especially desired because of their possible high hot hardness, chemical inertness with respect to the workpiece, and their low friction. This thesis deals with process and coating characterization of new oxide coatings deposited by physical vapor deposition (PVD) techniques, focusing on the Cr-Zr-O and Al-Cr-Si-O systems. The thermal stability of α-Cr0.28Zr0.10O0.61 deposited by reactive radio frequency (RF)-magnetron sputtering at 500 °C was investigated after annealing up to 870 °C. The annealed samples showed transformation of α-(Cr,Zr)2O3 and amorphous ZrOx-rich areas into tetragonal ZrO2 and bcc Cr. The instability of the α-(Cr,Zr)2O3 is surprising and possibly related to the annealing being done under vacuum, facilitating the loss of oxygen. The stabilization of the room temperature metastable tetragonal ZrO2 phase, due to surface energy effects, may prove to be useful for metal cutting applications. The observed phase segregation of α-(Cr,Zr)2O3 and formation of tetragonal ZrO2 with corresponding increase in hardness for this pseudo-binary oxide system also opens up design routes for pseudo-binary oxides with tunable microstructural and mechanical properties. The inherent difficulties of depositing insulating oxide films with PVD, demanding a closed circuit, makes the investigation of process stability an important part of this research. In this context, we investigated the influence of adding small amount of Si in Al-Cr cathode on plasma characteristics ,process parameters, and coating properties. Si was chosen here due to a previous study showing improved erosion behavior of Al-Cr-Si over pure Al-Cr cathode without Si incorporation in the coating. This work shows small improvements in cathode erosion and process stability (lower pressure and cathode voltage) when introducing 5 at % Si in the Al70Cr30-cathode. This also led to fewer droplets at low cathode current and intermediate O2 flow. A larger positive effect on cathode erosion was observed with respect to cleaning the cathode from oxide contamination by increasing cathode current with 50%. However, higher cathode current also resulted in increased amount of droplets in the coating which is undesirable. Through plasma analysis the presence of volatile SiO species could be confirmed but the loss of Si through volatile SiO species was negligible, since the coating composition matched the cathode composition. The positive effect of added Si on the process stability at the cathode surface should be weighed against Si incorporation in the coating. This incorporation may or may not be beneficial for the final application since literature states that Si promotes the metastable γ-phase over the thermodynamically stable α-phase of pure Al2O3, contrary to the effect of Cr, which stabilizes the α-phase.

Executive summary Today, packaging has gained a significant role in the food industry as well as other industries. Paper substrates that have been coated in some ways are typically used to make packaging. The amount and type of pigment used in the formulation determine whether this coating is a pigment coating or a barrier coating. Critical pigment volume concentration (CPVC) is the optimum spot when the pigments are packed as densely as possible, and the binder fills the air gaps. When the amount of pigment in a coating is less than CPVC, a barrier coating is formed, although when the amount of pigment in the coating is greater than CPVC, a pigment coating is formed. Pigment coating adds optical properties to a package, such as improved printability. And chemical protection is primarily provided for water, water vapour, fats, and gases in the case of the barrier coating. Chemical protection against these substances means, for food packaging, that the shelf life of the product will be extended, among other things. The role of packaging in society is expected to grow as barrier coatings on packaging continue to improve. The use of nanoclay in barrier coatings is investigated in this laboratory study. Two latexes are tested with nanoclay, with latex chosen based on its glass transition temperature (Tg). The hypothesis was that a latex with a higher Tg would have more properties like brittleness and orderly structure in its amorphous structure than the other latex. Latex with a lower Tg, on the other hand, would have more elasticity, be more ductile, and have a lower degree of ordered structure in its amorphous structure. Latex with a higher Tg was referred to as Hard latex and was composed of Styrene-butadiene, while latex with a lower Tg was referred to as Soft latex and was composed of Polyolefin dispersion, although it is unorthodox to call it latex. Previous research has found that the addition of Bentonite nanoclay can improve the mechanical and barrier properties of barrier coatings. Bentonite was therefore chosen as the nanoclay for this study due to having a higher aspect ratio, is flaky and can improve desired properties. The coating was applied as a dispersion coating using a lab-scale rod coater. The substrate for this study was BillerudKorsnäs FibreForm with a grammage of 150 g/m2.In order to find the optimum rod for the coating, three different rods were tested during screening test 1. The rods tested were based on the desired coating weight and thickness, a red rod with a wet film thickness of 12 μm was chosen. The nanoclay content of the latex formulation was investigated to determine the optimal level for improved barrier properties. In screening test 2, the concentrations examined were 2/4/8 w/w% nanoclay in each latex, and 0 w/w% to compare the difference with Hard/Soft latex to see if there are any benefits of nanoclay. For both latexes, the addition of 2/4 w/w% nanoclay resulted in more pinholes as well as a poor water vapour transmission rate and permeability. The results of screening test 2 showed that adding 8 w/w% nanoclay to both latexes improved the water vapour transmission rate, water vapour permeability, and pinholes test when compared to the other concentrations of nanoclay. In the water vapour transmission rate and pinholes test, however, 0 percent nanoclay performed similarly 8 w/w% for each latex formulation. The selected formulation for further study was 8 w/w% nanoclay with Hard/Soft latex.  Water vapour was the most important barrier property to investigate since barrier coatings were intended for food packaging. For the intended food packaging, it was sought that the barrier could be stretched with 3.8/6.7/10.4%-stretch and then characterized by water vapour transmission rate to be able to see the differences before and after stretching. Stretching with tensile tester were performed on a barrier coated FibreForm, first in the machine direction (MD), then in cross-direction (CD). Hydroforming with shaped bubbles was used for the second method of stretching with various bubbles. Stretching in MD + CD, and hydroforming bubbles were done according to the desired %-stretching. Characterization of the coating was done by water vapour transmission rate (WVTR) for all coatings, pinholes test for hydroformed coatings, water vapour permeability (WVP) and scanning electron microscopy (SEM) on tensile-stretched coatings. The performance of Soft latex with an 8 w/w% formulation stretched in MD then CD and characterized by water vapour transmission rate was significantly unchanged despite stretching up to 10.4%. This is thought to be because nanoclay, as the literature suggests, has created a better barrier against water vapour. The mean WVTR of 10.4%-stretching in MD then CD was 5.5 g/m2/day, compared to 5.5 g/m2/day for the unstretched barrier.  SEM images of both stretched and non-stretched coatings show that the dispersion of nanoclay is poor, as there are islands of polymer and nanoclay bulk. The poor dispersion of nanoclay in the matrix was due to the lack of polar groups in the backbone of Soft latex (Polyolefin) and also being hydrophobic, as opposed to Bentonite, which is hydrophilic. Despite poor nanoclay dispersion and a stretch of 10.4% in MD + CD, resulting in reduced barrier thickness, WVP improved from 289 g* /m2/day (pre-stress) to 191 g* /m2/day (10.4%-stretch), giving the impression of some reorientation of nanoclay in the polymer matrix. A crack was also visible in SEM images, near the boundary layer between the barrier and the substrate, on an unstretched coating, which is thought to be caused by the difference in the boundary layer and adhesive forces, that has occurred during drying. Cracks are not visible on the stretched barriers, even though it was expected. With increased stretching of hydroforming substrates coated with Soft latex formulation, the performance of water vapour transmission rate was significantly worse. The reason for this is thought to be that the barrier was damaged during hydroforming due to friction during pressing and shaping, as the hydroforming was done on the barrier side. The pinhole test revealed clearly degraded performance with a large number of pinholes. This could indicate that the barrier has been stretched beyond its capacity or has been damaged. There was no correlation found between stretching in tensile tester and hydroforming.  Hard latex with an 8 w/w% formulation stretched in MD then CD and characterized by water vapour transmission rate could be stated to have significantly improved performance despite stretching up to 10.4%. The mean-WVTR of 10.4%-stretching in MD then CD was 11.3 g/m2/day, compared to 16.4 g/m2/day for the unstretched barrier. According to SEM images, the reason for this is that nanoclay was very well dispersed in the matrix and that there has seemingly been a slight reorientation of nanoclay with increased stretch. Furthermore, SEM images show that the thickness was reduced, yet despite this, mean-WVP improved from 1094 g* /m2/day (pre-stress) to 419 g* /m2/day (10.4%-stretch), indicating reorientation of nanoclay and thus improved stretchability.These SEM images show cracks at the boundary layer between the barrier and the substrate for both unstretched and 10.4%-stretched barriers in the Hard latex formulation. The cracks are seemingly stopped by nanoclay in the matrix, according to the stress concentration effect, where the crack moves around nanoclay and not through nanoclay. Hydroforming of barrier coated Hard latex formulation showed a deterioration of water vapour transmission rate with increased stretching. The mean WVTR of hydroforming with 10.4%-stretching was 30.6 g/m2/day. It is not thought that pressing during hydroforming damaged the Hard latex barrier as much, which can be confirmed by the pinholes test. Pinholes test demonstrated good performance and comparable to an unstretched barrier. Because comparisons between the different polymers were impractical, it was not possible to state if the glass transition temperature was important for the improvement seen by stretching in the tensile tester. But it can be argued that Hard latex has a more structured and rigid structure, allowing for a greater degree of reorientation. Soft latex, on the other hand, has less stiffness and thus less reorientation. The result of this study is that when stretching is done in both tensile testing and hydroforming, 8 w/w% nanoclay (bentonite) with Hard latex (styrene-butadiene) can be used advantageously in FibreForm packaging if stretchability is desired while maintaining barrier properties against water vapor. / Sammanfattning Idag har förpackningar fått en betydande roll i matindustrin såväl som andra industrier. Vid bestrykning på förpackningar och papperssubstrat så är det vanligt med pigment- eller barriärbestrykning. Vid pigmentbestrykning så tillförs optiska egenskaper till förpackningen, såsom exempelvis förbättrad tryckbarhet. Vid barriärbestrykning tillförs huvudsakligen kemisk skydd mot exempelvis vatten, vattenånga, fetter eller gaser, och innebär för matförpackningar bland annat att hållbarheten blir längre för livsmedlet. Genom fortsatt utveckling av barriärbestrykningar på förpackningar så förväntas även förpackningens roll i samhället att bli större. I denna laborativa studie undersöks möjligheterna kring töjbara barriärer på papperssubstrat, med fokus på vattenångaresistans.  De formuleringar som togs fram bestod av en latex med låg glasövergångstemperatur (Tg), kallad Soft latex med implementerad nanolera samt en latex med en Tg kallad Hard latex med implementerad nanolera. Soft latex var en Polyolefin dispersion med Tg -30°C, och Hard latex var en Styren-butadien latex med Tg = 0°C. 8 w/w% nanolera var den halt som bedömdes ge förbättringar i de mekaniska samt barriäregenskaper som eftersöktes för de båda latex. För denna studie valdes Bentonit som nanolera, på grund av dess plana samt dess fjälliga (flaky) struktur.  Töjbarheten hos de framtagna barriärformuleringarna testades med töjning i dragprov först i maskin-riktning (MD) och sedan tvär-riktning (CD) samt töjning med hydroforming, med töjning på 3,8/6,7/10,4% för respektive metod. Efter töjning av respektive metod bestämdes överföringshastigheten av vattenångpermabilitet (WVTR) genom barriären. En jämförelse gjordes mellan töjning i dragprov och hydroforming för att få en ökad förståelse kring WVTR-prestationen beroende på metod av töjning.  Soft latex visade en oförändrad vattenångaresistans efter 10,4%-töjning i dragprovaren. Detta tros bero på att nanoleran försvårar vattenångan att genomträngas trots töjning. Vid elektronmikroskop (SEM) kunde det ses att dispersionen av nanolera med Soft latex inte var bra, och därför var inte förbättringarna lika tydliga. Den sämre dispersionen av nanolera i matrisen beror på att Polyolefin saknar polära grupper i dess ryggrad (backbone) samt är väldigt hydrofobt, till skillnad från Bentonit som är hydrofilt. Trots sämre dispersion av nanolera och en töjning på 10,4% i MD + CD, så förbättrades vattenånga permeabiliteten (WVP).För hydroforming var prestationen av Soft latexformuleringen gällande WVTR dåliga, och vid Pinholes test fanns det uppenbara pinholes.  Hard latex visade en tydlig förbättring av WVTR efter 10,4%-töjning i dragprovaren, som tros bero på en omorientering av nanoleran i polymer matrisen vid töjning, vilket kan bekräftas av elektronmikroskop (SEM) där viss omorientering är synlig. Dessutom sågs en tydlig förbättring i WVP trots en lägre barriärtjocklek.För hydroforming var WVTR-värdena liknande till endast Hard latex och 0% nanolera.  Vid töjning var jämförelser beroende på de olika glasövergångstemperaturerna hos polymererna inte möjlig, och därför inte heller möjligt att konstatera ifall glasövergångstemperaturen var viktig för den förbättring som setts trots töjning i dragprovare. Men det kan hävdas att Hard latex har en mer strukturerad och stel struktur, vilket möjliggör en större grad av omorientering. Soft latex däremot, är mindre styvt och mindre ordnat, därav åstadkoms en mindre omorientering.  Resultaten av denna studie är att när stretching görs i både dragprovning och hydroformning, kan 8 w/w% nanoclay (bentonit) med Hard latex (styren-butadien) vara fördelaktig i FibreForm-förpackning om töjbarhet önskas samtidigt som barriäregenskaperna mot vattenånga bibehålls.

This paper reviews the effects of accelerated aging with increased humidity and temperature on cellulose-based composites. The composites consist of a matrix of plastic reinforced with cellulose fibers. The company Biofiber Tech Sweden AB provided four different composites and a conventional polyolefin as reference. The aim was to examine changes in mechanical properties, chemical composition and appearance after aging, as well as variations between materials. Two different climate conditions were tested, 85% RH and &lt;10% RH, both in 90℃. A climate chamber and an oven were used to create the extreme environmental conditions. To analyze the results, tensile testing and FTIR were performed, and color intensity and density were measured. All samples decreased in color intensity throughout aging, and dark irregularities appeared on some of the samples exposed to high humidity, which may be due to fungal formation. The tensile testing showed a general difference between high and low RH and the toughness showed a tendency to decline with aging in high humidity for many samples. The FTIR measurements also did not show any general trend. To improve the study, it would be desirable to age the material for a longer time and at a higher temperature. Overall, more samples and measurements within each characterisation technique would be needed to achieve more reliable results. Nevertheless, this study hopes to be a starting point for further research on the long-term durability of Biofiber Tech’s composites.

Na-ion batteries (NIBs) are expected to revolutionise the battery sector by promising an affordable technology while capitalising on sustainable development. To compete with Li-ion batteries, however, electrode materials with higher capacities need to be developed. Transition metal nitroprussides (TM-NPs), NaxM[Fe(CN)5NO]1-y ·zH2O, is a material class derived from one of the most popular positive electrode materials for NIBs, Prussian blue analogues (PBAs), where one of the cyano ligands have been replaced by an electroactive nitrosyl (NO) ligand. Thus, in theory TM-NPs should be able to reach higher capacities than PBAs and therefore be attractive candidates for high-capacity electrodes. However, if the nitrosyl is redox active in NIBs and how the cycling behaviour may be affected by the M cation is unknown. The focus in this thesis is therefore to explore the charge-discharge behaviour of four different TM-NPs (M=Fe, Ni, Mn, and Cu) in Na-ion half-cell batteries to gain an initial understanding of their electrochemical behaviour and to set up research questions to be pursued in the future. Based on our observations and previous studies, we propose that the nitrosyl is electrochemically active in all four TM-NPs, and that it contributes with a considerable amount of capacity, although with a large voltage hysteresis. It is further concluded that all M cations apart from Ni were redox active, but to varying degrees on charging and discharging. We argue that both the redox and the voltage hysteresis is caused by anisotropic charge transfer within the materials, and that it needs to be understood before commercialisation of TM-NPs can be realised. Though there are challenges to overcome, the many interesting attributes of TM-NPs, including anionic redox, anisotropic charge transfer and structural diversity, makes them promising as a new type of cheap and sustainable electrode material for NIBs.

In this work, the use of a lunar regolith simulant as feedstock for the direct ink writing additive manufacturing process is explored, the purpose of which is to enable future lunar in-situ resource utilisation. The feasibility of this approach is demonstrated in a laboratory setting by manufacturing objects with different geometries using methyl cellulose or sodium alginate as binding agents and water as liquid phase together with the lunar regolith simulant EAC-1A to create a viscous, printable ‘ink’ that is used in combination with a custom three-axis gantry system to produce green bodies for subsequent sintering. The sintered objects are characterised using compressive strength measurements and scanning electron microscopy (SEM). It is proposed that the bioorganic compounds used in this work as additives could be produced at the site for a future lunar base through photosynthesis, utilising carbon dioxide exhaled by astronauts together with the available sunlight, meaning that all the components used for the dispersion – additive, water (in the form of ice) and regolith – are available in-situ. The compressive strength for sintered samples produced with this method was measured to be 2.4 MPa with a standard deviation of 0.2 MPa (n = 4). It is believed, based on the high sample porosity observed during SEM analysis, that the comparatively low mechanical strength of the manufactured samples is due to a non-optimal sintering procedure carried out at a too-low temperature, and that the mechanical strength could be increased by optimising the sintering process further.

This master’s thesis was conducted at the Department of Nanotechnology and Functional Materials at Ångström Laboratory as part of an on-going project to develop hybrid nanocomposites from Cladophora cellulose and a sub-type of metal-organic frameworks; zeolitic imidazolate frameworks (ZIFs). By utilizing a state-of-the-art interfacial synthesis approach, in-situ growth of ZIF particles on the cellulose could be achieved. TEMPO-mediated oxidation was diligently used to achieve cellulose nanofibers with carboxylate groups on their surfaces. These were ion-exchanged to promote growth of ZIF particles in a nanocellulose solution and lastly, metal ions and organic linkers which the ZIFs are composed of were added to the surface functionalized and ion-exchanged nanocellulose solution to promote ZIF growth. By vacuum filtration, mechanical pressing and furnace drying; freestanding nanopapers were obtained. A core-shell morphology between the nanocellulose and ZIF crystals was desired and by adjusting the metal ion concentration, a change in morphologies was expected. The nanocomposites were investigated with several relevant analytical tools to confirm presence, attachment and in-situ growth of ZIF crystal particles upon the surface of the fine nanocellulose fibers. Both the CNF@ZIF-67 and CNF@ZIF-8 nanocomposites were successfully prepared as nanopapers with superior surface areas and thermal properties compared to pure TEMPO-oxidized cellulose nanopapers. The CNF@ZIFs showcased hierarchical porosities, stemming from the micro- and mesoporous ZIFs and nanocellulose, respectively. Also, it was demonstrated that CNF@ZIF-8 selectively adsorbed CO2 over N2. Partial formation of core-shell structure could be obtained, although a relationship between increased metal ions and ZIF particle morphology could not wholly be observed.