The main scope of this work was to investigate whether it is possible to produce free standing 3D structures by the means of spraying and using MFC as raw material. This was carried out by diluting MFC into a consistency of 2% and spraying it onto a male mould. During the trials, several different devices and procedures were investigated in order to find a possible solution. The results from the laboratory trials showed that it is possible to create trays of MFC that could suitable as a detail for packaging. The important thing was to pre-heat the mould before spraying, build the tray in layers, where spraying should be carried out in a 45° angle, with single sweeps while rotating the mould in the beginning of the process, and to use a drying method, were the drying could be focused on the wet parts at the same time as it could avoid those who already had been dried, to dry the sample between each layer of MFC until the wet surface disappeared. Exactly how many sweeps per layer that should be sprayed after the first drying does not matter much, the important thing was that the layers do not become too thick. Because then, too much moisture was trapped inside the samples which made them burst during the drying.

The research presented herein aims to develop a bio-inspired swimming system for an autonomous underwater vehicle using Macro-Fiber Composite (MFC) actuators. The swimming system draws inspiration from the motion of carangiform fish, which limit their body motion while rapidly oscillating their caudal tail fin. The foundation for the bio-inspired swimming system is built upon a composite cantilever beam with MFC actuators in bimorph configuration. The MFC actuators excite the composite beam near its fundamental natural frequency to produce thrust as the vibration transfers momentum to the surrounding fluid. An analytical model that incorporates Euler-Bernoulli beam theory, linear piezoelectricity, and fluid mechanics is developed to predict the thrust generated by the beam vibration. Experimental testing is performed to verify aspects of, as well as recommend corrections to, the analytical model. A prototype carangiform swimmer is developed that employs a passive caudal tail fin to alter the vibratory motion of the system from a beam vibration mode to one more resembling carangiform swimming. This device is subjected to experimental testing to determine the swim speeds it is able to achieve. A maximum velocity of 90mm/s was observed when the system is excited at 900V. However, better performance may be achieved by increasing the excitation voltage. / Master of Science

No description available.

In this thesis, two MFC based films Carboxymethylated-Microfibrillated Cellulose (MFC) and Enzymatic-MFC were characterized and metalized in order to improve the barrier properties at high relative humidity. Several methods were used for the characterization process, which were Atomic Force Microscopy (AFM), Contact Angle (CA), Energy Dispersive Spectra (EDS), Light Microscopy (LM), Scanning Electron Microscopy (SEM), and Oxygen Transmission Rate (OTR). Physical Vapor Deposition (PVD) system was used for the metalization of film, a thin layer of aluminium with a thickness of 200 nm was deposited on the films. The results revealed that ENZ-MFC exhibit a higher roughness and lower OTR values, compared to CM-MFC. The contact angle values proved that both non-metalized MFC films exhibited a hydrophilic surface with values around 50 degrees. SEM and EDS images showed that both films exhibited surface defects with dimensions in the order of a micrometer. The best barrier improvement by metalization was achieved for the metalized CM-MFC, where the OTR values were decreased by one order of magnitude after metalization. However, for ENZ-MFC metalization did not improve OTR at high RH. The protective layer was successfully protecting the MFC film as long as the surface roughness of the film was not too high. The limit is between 40 and 140nm (in root mean square roughness values). / I denna avhandling karakteriserades två MFC-baserade filmer Carboxymethylated-MFC och   Enzymatic-MFC som metalliserades för att förbättra barriäregenskaperna vid hög relativ fuktighet. Flera metoder har används för karaktäriseringsprocessen, vilka var Atomic Force Microscopy (AFM), Contact Angle (CA), Energy Dispersive Spectra (EDS), Light Microscopy (LM), Scanning Electron Microscopy (SEM), och Oxygen Transmission Rate (OTR). Physical Vapor Deposition (PVD) systemet användes för metalliseringen av filmerna, där ett tunt skikt aluminium med en tjocklek av 200 nm deponerades. Resultaten visade att ENZ-MFC har högreråhet och lägre OTR-värden jämfört med CM-MFC. Kontaktvinkelvärdena påvisade att bådaicke-metalliserade MFC-filmer har en hydrofil yta med värden omkring 50 grader. SEM- och EDS-bilder visade att båda filmerna har ytdefekter i storleksordningen en mikrometer. Den bästa barriärförbättringen genom metallisering uppnåddes för den metalliserade CM-MFC, där OTR-värdena minskade med en storleksordning efter metallisering. För ENZ-MFCförbättrade dock metallisering inte OTR vid hög RH. Det skyddande skiktet skyddar effektivt MFC-filmen så länge som filmens ytråhet inte var för hög. Gränsen är intervallet mellan 40 och140 nm (Kvadratiskt medelvärde för ytråhet).

No description available.

Piezoceramic fiber composite (PFC) actuators and sensors offer many advantages over conventional monolithic piezoceramic devices. Conformable, durable and, when equipped with interdigitated electrodes (IDEs), more responsive than regular monolithic devices, PFCs promise to revolutionize the application of piezoelectric materials. Developed by the NASA-Langley Research Center, the Macro-Fiber Composite (MFC) actuator and sensor is the most sophisticated PFC device yet invented. With superior qualities among PFCs in performance, behavior repeatability and manufacturability, the MFC has spawned great interest in the commercial and academic community as a tool in multitudinous engineering applications. While the MFC's characteristics render it a singularly useful device, limited characterization and modeling research on the MFC exists. Empirically designed and assembled, the MFC is poorly understood, especially in terms of its underlying operating principles, its dependence on design parameters and its electrical properties. The majority of published MFC studies focus on experimental quantification of MFC mechanical and actuation properties, and the research that attempts to model the MFC relies totally on finite element analysis. Published works widely assume that analytical models of the MFC are totally impossible. Rectifying gaps in the current body of MFC research, this study presents the first accurate analytical model of the static electrical field properties of the MFC. Implementing the techniques of conformal mapping, a branch of complex analysis, the following chapters derive a closed-form, exact analytical solution describing the electrical potential field and electrical field of the MFC's dual-IDE structure. Based on the conformal mapping solution for the MFC's electrical field, the electrical field of the commercially available MFC is examined and analyzed, introducing an intuitive knowledge of the MFC's operation. Demonstrating the utility of this solution in modeling the MFC, this work also predicts the capacitance and induced strain properties of a continuum of potential MFC designs and offers final suggestions on improving the current commercial MFC design. After establishing the theoretical underpinnings of the analytical MFC model, this report derives the conformal mapping solutions for the MFC, discusses the computational application of the resulting equations and then presents the results of numerical analyses executed using the new analytical model. / Master of Science

In this thesis, Atomic Force Microscopy (AFM) is used to characterize Micro Fibrillated Cellulose (MFC) produced by two different methods according to their size and shape. For one of these MFC-types, their interaction with the humidity in the atmosphere is investigated and their swelling is calculated. MFC is a relatively new material based on cellulose fibres extracted from wood. This study is performed in co-operation with Stora Enso research centre. Stora Enso is a renewable material company which uses mostly wood based raw materials in their production. The measured swelling is ~ 5 % and depends on the number of elementary fibrils included in the fibre. / Atomkraftsmikroskopi (AFM) har använts för att karakterisera Mikro Fibrillerad Cellulosa (MFC), som är producerad med två olika produktionsmetoder, med avseende på deras storlek och form. För en av dessa MFC-typer så är deras påverkan av en varierande fuktig atmosfär undersökt och deras svällning är uträknad. MFC är ett relativt nytt material baserat på cellulosafibrer från trä. Detta examensarbete är utfört i samarbete med Stora Enso forskningscentrum. Stora Enso är ett företag fokuserat på förnyelsebara material som använder mestadels träbaserade råmaterial i deras prodiktion. Den uppmätta svällningen är ~ 5 % och beror av antalet elementära fibriller som ingår i fibern.

Nanoparticles are very interesting building blocks. Their large surface-to-bulk ratio gives them different properties from those of larger particles. Controlling their assembly can greatly affect macroscopic material properties. This often happens in nature, resulting in macroscopic materials with properties far better than those of similar human-made materials. However, in this fast-growing research field, we may soon compete with nature in certain areas. This thesis demonstrates that the distribution and orientation of nanocellulose particles can be controlled, which is crucial for many applications. Nanocellulose is an interesting nanoparticle, for example, because of its high strength, low thermal expansion, and high crystallinity. Nanocellulose particles are called nanofibrillated cellulose (NFC) or cellulose nanocrystals (CNCs). NFC is obtained from wood by mechanically shearing apart fibrils from the fiber wall and to obtain CNCs, parts of the cellulose are broken down by hydrolytic acidic reactions, most commonly, prior to homogenization. NFC particles are longer and less crystalline than are CNCs, but both are similar in width. The particles attract each other in aqueous dispersions and have a high aspect ratio and, thus, a large tendency to aggregate. The rate at which this occurs is typically reduced by charging the particles, generating an electrostatic repulsion between them. To fully utilize the many interesting properties of nanocellulose, the aggregation and orientation of the particles have to be controlled; examining this delicate task is the objective of this thesis. The limits for particle stability and aggregation are examined in papers 2–3 (as well as in this thesis) and orientation of the particles is investigated in papers 3–5. In addition, the liberation of the nanoparticles from different types of wood fibers is studied in papers 1 and 2. It was found that the liberation yield improved with increased fiber charge. In addition, the charge of the fibrils is higher than the charge of the original fibers, indicating that the fibrils were liberated from highly charged parts of the fibers and that the low-charge fraction was removed during processing. Aggregation was both theoretically predicted and experimentally studied. A theoretical model was formulated based on Derjaguin–Landau–Verwey–Overbeek theory, which is intended to predict the influence of salt, pH, and particle charge on the colloidal stability of the NFC. To predict the experimental trends, specific interactions between salt counterions and the particles charges had to be included in the model, which greatly increased the effect of salt on the NFC stability. Below the particle overlap concentration, instability induced by pH or salt created small sedimenting flocs, whereas above the overlap concentration the system gelled. Increasing the particle concentration further also gels the system. Orientation of nanocellulose was first achieved by shearing, salt- or acid-induced NFC gels. This oriented the fibrils and increased the gel modulus in the direction of shear. The orientation persisted after the shear strain was released and did not cause breakdown of the macroscopic gel. The orientation is probably due to rotation in the interfibril crosslinks, which is possible because the crosslinks are physical, not covalent.      Second, orientation was also induced by elongational flow. Shear and acceleration forces were combined to align fibrils in the direction of the flow. The orientation was then frozen by gelation (adding salt or reducing the pH). Drying the gel threads created filaments of aligned fibrils with a higher specific strength than that of steel.      Finally, CNC particles could be aligned on flat surfaces. The particles were first forced to align due to geometrical constraints in grooves on a nanowrinkled surface. The CNCs were then transferred to a flat surface using a contact-printing process. This created surfaces with lines of highly aligned CNCs, where the line–line spacing was controlled with nanometer precision. / <p>QC 20131114</p>

Wastewater treatment is an energy intensive process and sustainable processes/technologies for the treatment of wastewaters need to be considered. One such contender might be the microbial fuel cell (MFC), a subset of bioelectrochemical system (BES) which generates electricity in the process of electrogenic (generating electrons) degradation of soluble organic contaminants present in the water (or wastewater) by electrogens (electron producing bacteria) at the anode in absence of oxygen. Several issues related to the power performance (also somewhat linked to the cost) of MFCs exist causing barriers in the deployment of up-scaled MFC system and the continual research from a multitude of discipline is focusing on overcoming these issues. Implementation of an MFC system for wastewater treatment would require a large array of MFCs to meet the treatment capacity of the wastewater treatment plant. Commissioning and continual operation of such MFCs would require rapid and cost-effective start-up and improvement in their performance. Optimisation of the power performance is addressed through a systems approach in this study, where improvement in the performance is sought through the system design and control strategies applied to the MFCs. The start-up rate of MFCs has been reduced by 45% using maximum power point tracking (MPPT), which is believed to be cost-effective as exogenous energy (such as in the case of poised-potential) is not required for the rapid start-up. The control of MFC power would need to be considered when up-scaled MFC system is realised. The controller implementation benefits from linearised system models. The viability of such piecewise linearisation of the nonlinear MFC system was demonstrated and the data were shown to be reasonably represented by the 1st order process models throughout its operating range. The occurrence of voltage reversal during stack operation of MFCs is a concern in large arrays particularly, and has been shown to be avoidable by adopting the hybrid stack connectivity. Further enhancement of the performance was sought through the detailed design and fluid dynamics modeling to obtain highly mixed anolyte at low input power, using improved helical anodes which increased the MFC performance at all the tested flow rates (1, 3 and 8 mL min-1) compared to previously studied helical anodes. The up-scaling of MFCs by modularisation was demonstrated and it was shown that the use of improved helical anodes can increase the modular length of the MFC without compromising the power performance. Aggregated power produced from the multi-module MFC (containing 5 modules) was 28.05 ± 3.5 mW (19.75 ± 2.47 W m-3) with an PhD Thesis – Hitesh Chandubhai Boghani 2014 V individual MFC power of 5.61 ± 0.7 mW, when fed with 10 mM sodium acetate at 3 mL min-1 flow rate and at 22 ± 3 °C. So, this thesis presents the strategies for improvement in the performance of MFCs for their applications in wastewater treatment and such strategies may also be transferable to their other applications.

Syftet med projektet var att undersöka hur homogeniserings förhållanden (tryck antal passager och därmed energiinsatsen) vid framställning av MFC (mikrofibrillär cellulosa), från enzymatiskt förbehandlade pappersmassafibrer påverkar hållfastheten av papper förstärkt med MFC. Arbetsgivaren för projektet var Innventia och det laborativa arbetet har utförts i deras lokaler. Fördelen med att använda MFC som tillsats i papper är att arket blir starkare [1]. Detta medför att en mindre mängd material kan användas till ett material med liknande styrkeegenskaper. Vid Innventia används för närvarande en homogenisator för att delaminera (sönderdela) cellulosafibrer till fibriller och fibrillaggregat och därmed producera MFC. Homogenisatorn kan köras vid olika tryck, samt att cellulosafibrerna/MFC kan låtas passera genom homogenisatorn en eller flera gånger. Beroende på tillvägagångssättet varierar produktionsenergin mycket och egenskaperna på den producerade MFC varierar. För att få en så energieffektiv metod som möjligt är det av stor vikt att finna vilken metod som genererar en MFC lämpad för styrkegivning i pappersark. Beroende på hur mycket MFC som tillsätts till arket kan arkets egenskaper variera. Därför är även detta en mycket viktig aspekt att ta hänsyn till då dubbla mängden tillsatt MFC direkt motsvarar dubbla mängden tillförd energi. För att få en jämn dispergering av massafibrer och inbunden MFC utfördes retentionsförsök för att bestämma vilken koncentration C-PAM 1510 som ansågs lämplig att använda vid arkningen för samtliga MFC prover. C-PAM 1510 är en positiv laddad polymer som binder in MFC till massafibrerna [2]. Maskinen som användes för retentionsförsöken är BDDJ (Britt Dynamic Drainage Jar) och syftar till att se hur mycket MFC som retenderar med massafibrerna. Arkningen utfördes enligt ISO 5269-1 med riktvärde att producera ark om 80g/m2 för vidare fysikaliska tester, bland annat dragprovning, densitet och reell ytvikt. Halten C-PAM 1510 som användes under arkningsförsöken bestämdes till 0,15 %. Det fanns ingen säkerställd skillnad i arkstyrka för de olika MFC proverna som testades, förutom prov ett. Prov ett gav en betydande högre mätvärdesvariation vid dragprovningen (figur 8) jämfört med de övriga proverna och får ses extremt påverkad av något. Detta var inte heller ett prov som påverkade slutsatsen. Därav har prov ett utelämnats i diagram. Prov nummer 5 ansågs bäst lämpad som styrkeadditiv i papper. Resultaten kan dock ha påverkats av föroreningar i kranvattnet. Järnjoner och partiklar i varierande koncentrationer hade en påverkan av dispergeringen av fibrer i pappersark. / The goal with the project was to investigate how homogenization conditions (pressure, number of passes and thereby energy consumption) at production of MFC (microfibrillated cellulose), from enzymatic pretreated paper mass fibers affects the strength of paper enhanced with MFC. The employer of the project is Innventia and the laboratory work was conducted in their facilities. The advantage of using MFC as an enhancer in paper is that the paper becomes stronger and more durable [1]. This leads to a decreasing use of material for a paper with similar strength properties as ordinary paper. At Innventia they presently use a homogenisator to delaminate (break apart) cellulose fibers to fibrils and fibril aggregates and thereby produce MFC. The homogenisator can be operated at different pressures and also the cellulose fibers/MFC can pass through one or several times. Depending on the method the energy consumption will greatly vary and so will also the properties of the produced MFC. To make the process as energy efficient as possible it is of most importance to find the best method of production for a MFC suitable as an enhancer in paper. Depending on how much MFC is added to the paper, the papers properties will vary. Therefore this aspect is also important to consider, because if the added MFC doubles, the energy does too. To make an even dispersion of the pulp fibers and adsorbed MFC, retention experiments were conducted to determine which concentration of C-PAM 1510 was most suitable to use during the sheet forming for every MFC sample. C-PAM 1510 is a positively charge polymer that can bind MFC to cellulose fibers [2]. The machine used for the retention experiments was BDDJ (Britt Dynamic Drainage Jar) aiming to determine how much MFC retain in the paper mass. The sheet forming was conducted accordingly to ISO 5269-1 and 80g/m2 sheets where produced for further physical testing, among other things, tensile test, density and basis weight. The C-PAM 1510 concentration used during the sheeting was determined to 0,15 %. There was no big difference for tensile strength compared to the different MFC samples, except sample one. Sample one had significant higher coefficient of variation compared to the other samples (figure 8) during tensile strength test, probably due to a high influence of some interference. The exclusion of sample one did not affect the overall result. Therefore sample one was excluded from diagrams. Sample number 5 was considered to be the best strength enhancing additive for paper. The results may have been influenced by impurities in the tap water and should be considered. Iron ions and particles in various concentrations did have an effect of the dispersion of fibers in paper.