Tesis por compendio / [EN] Direct methanol fuel cells are feasible devices for efficient electrochemical power generation if some issues can be solved regarding both electrodes and membranes. The research carried out in this Ph.D. thesis has particularly focused on the concerns associated with the membranes. Nafion is the most standard fuel cell membrane material due to its high proton conductivity and exceptional chemical and mechanical stability. However, it suffers from a considerably high methanol permeability and a limited operating temperature (< 80 ºC). The first aspect was addressed with the use of PVA nanofibres and the second one replacing Nafion with SPEEK-based polymers. Composite membranes of Nafion with PVA nanofibres, surface functionalised with sulfonic acid groups, exhibited lower methanol permeabilities due to the intrinsic barrier property of PVA, although proton conductivity was also affected as a result of the non-conducting behaviour of the bulk PVA phase. Remarkably, the nanofibres provided strong mechanical reinforcement which enabled the preparation of low thickness membranes (< 20 micrometres) with reduced ohmic losses, thus counteracting their lower proton conductivities. SPEEK-based membranes were examined for DMFC operation within the intermediate temperature range of 80-140 ºC, in which sluggish electrochemical reactions at the electrodes are accelerated and proton conductivity activated. SPEEK was blended and crosslinked with PVA and PVB polymers for avoiding its dissolution in hot water conditions. SPEEK-PVA compositions showed practical proton conductivities and SPEEK-PVB blends presented very low methanol permeabilities. Nanocomposite membranes composed of SPEEK-30%PVB nanofibres embedded in a SPEEK-35%PVA matrix were prepared and characterised. A nanocomposite membrane crosslinked at 120 ºC revealed promising results for DMFCs operating at intermediate temperatures. Electrospinning is concluded to be a suitable technique for obtaining polymer nanofibre mats intended for advanced composite membranes with improved characteristics and fuel cell performances. / [ES] Las pilas de combustible de metanol directo son dispositivos factibles para la generación electroquímica eficiente de energía eléctrica si se pueden solucionar algunas cuestiones relacionadas tanto con los electrodos como las membranas. La investigación llevada a cabo en esta tesis doctoral se ha centrado particularmente en los problemas asociados con las membranas. Nafion es el material de membrana más común para pilas de combustible debido a su alta conductividad protónica y excepcional estabilidad química y mecánica. Sin embargo, padece una considerablemente alta permeabilidad al metanol y una limitada temperatura de operación (< 80 ºC). El primer aspecto se abordó con el uso de nanofibras de PVA y el segundo reemplazando Nafion con polímeros basados en SPEEK. Membranas compuestas de Nafion con nanofibras de PVA, funcionalizadas en su superficie con grupos ácidos sulfónicos, exhibieron menores permeabilidades al metanol debido a la propiedad barrera intrínseca del PVA, aunque la conductividad protónica también se vio afectada como resultado del comportamiento global no conductor de la fase de PVA. Remarcablemente, las nanofibras proporcionaron un refuerzo mecánico fuerte que permitió la preparación de membranas de bajo espesor (< 20 micrómetros) con unas pérdidas óhmicas reducidas, así contrarrestando sus menores conductividades protónicas. Se examinaron membranas basadas en SPEEK para la operación de pilas de combustible de metanol directo dentro del rango intermedio de temperaturas entre 80-140 ºC, en el que las lentas reacciones electroquímicas en los electrodos se aceleran y la conductividad protónica se activa. El SPEEK se combinó y entrecruzó con los polímeros de PVA y PVB para evitar su disolución en condiciones de agua caliente. Las composiciones de SPEEK-PVA mostraron conductividades protónicas funcionales y las mezclas de SPEEK-PVB presentaron permeabilidades al metanol muy bajas. Se prepararon y caracterizaron membranas nanocompuestas constituidas por nanofibras de SPEEK-30%PVB embebidas en una matriz de SPEEK-35%PVA. Una membrana nanocompuesta entrecruzada a 120 ºC reveló resultados prometedores para pilas de combustible de metanol directo operando a temperaturas intermedias. Se puede concluir que la electrohilatura es una técnica apropiada para la obtención de mallas de nanofibras poliméricas destinadas a membranas compuestas avanzadas con características y rendimientos en pilas de combustible mejorados. / [CA] Les piles de combustible de metanol directe són dispositius factibles per a la generació electroquímica eficient d'energia elèctrica si es poden solucionar algunes qüestions relacionades tant amb els elèctrodes com les membranes. La investigació duta a terme en esta tesi doctoral s'ha centrat particularment en els problemes associats amb les membranes. Nafion és el material de membrana més comú per a piles de combustible a causa de la seua alta conductivitat protònica i excepcional estabilitat química i mecànica. No obstant això, patix una considerablement alta permeabilitat al metanol i una limitada temperatura d'operació (< 80 ºC). El primer aspecte es va abordar amb l'ús de nanofibres de PVA i el segon reemplaçant Nafion amb polímers basats en SPEEK. Membranes compostes de Nafion amb nanofibres de PVA, funcionalizades en la seua superfície amb grups àcids sulfónics, van exhibir menors permeabilitats al metanol a causa de la propietat barrera intrínseca del PVA, encara que la conductivitat protònica també es va veure afectada com resultat del comportament global no conductor de la fase de PVA. Remarcablement, les nanofibres van proporcionar un reforç mecànic fort que va permetre la preparació de membranes de baixa grossària (< 20 micròmetres) amb unes pèrdues òhmiques reduïdes, així contrarestant les seues menors conductivitats protòniques. Es van examinar membranes basades en SPEEK per a l'operació de piles de combustible de metanol directe dins del rang intermedi de temperatures entre 80-140 ºC, en el que les lentes reaccions electroquímiques en els elèctrodes s'acceleren i la conductivitat protònica s'activa. El SPEEK es va combinar i va entrecreuar amb els polímers de PVA i PVB per a evitar la seua dissolució en condicions d'aigua calenta. Les composicions de SPEEK-PVA van mostrar conductivitats protòniques funcionals i les mescles de SPEEK-PVB van presentar permeabilitats al metanol molt baixes. Es van preparar i caracteritzar membranes nanocompostes constituïdes per nanofibres de SPEEK-30%PVB embegudes en una matriu de SPEEK-35%PVA. Una membrana nanocomposta entrecreuada a 120 ºC va revelar resultats prometedors per a piles de combustible de metanol directe operand a temperatures intermèdies. Es pot concloure que l'electrofilatura és una tècnica apropiada per a l'obtenció de malles de nanofibres polimériques destinades a membranes compostes avançades amb característiques i rendiments en piles de combustible millorats. / Mollá Romano, S. (2015). Application of Nanofibres in Polymer Composite Membranes for Direct Methanol Fuel Cells [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/58611 / Premios Extraordinarios de tesis doctorales / Compendio

Yes / Three dimensional printing (3DP) was used to engineer novel oral drug delivery devices, with specialised design configurations loaded with multiple actives, with applications in personalised medicine. A filament extruder was used to obtain drug-loaded - paracetamol (acetaminophen) or caffeine - filaments of polyvinyl alcohol with characteristics suitable for use in fused-deposition modelling 3D printing. A multi-nozzle 3D printer enabled fabrication of capsule-shaped solid devices, containing paracetamol and caffeine, with different internal structures. The design configurations included a multilayer device, with each layer containing drug, whose identity was different from the drug in the adjacent layers; and a two-compartment device comprising a caplet embedded within a larger caplet (DuoCaplet), with each compartment containing a different drug. Raman spectroscopy was used to collect 2-dimensional hyper spectral arrays across the entire surface of the devices. Processing of the arrays using direct classical least squares component matching to produce false colour representations of distribution of the drugs showed clearly the areas that contain paracetamol and caffeine, and that there is a definitive separation between the drug layers. Drug release tests in biorelevant media showed unique drug release profiles dependent on the macrostructure of the devices. In the case of the multilayer devices, release of both drugs was simultaneous and independent of drug solubility. With the DuoCaplet design it was possible to engineer either rapid drug release or delayed release by selecting the site of incorporation of the drug in the device, and the lag-time for release from the internal compartment was dependent on the characteristics of the external layer. The study confirms the potential of 3D printing to fabricate multiple-drug containing devices with specialized design configurations and unique drug release characteristics, which would not otherwise be possible using conventional manufacturing methods. / The full-text of this article will be released for public view at the end of the publisher embargo on 10 Oct 2016.

Bei angeborenen Herzfehlern, die bei 1 bis 1,2 % aller Lebendgeburten auftreten und so-mit die häufigste behandlungsbedürftige Organfehlbildung darstellen, kommen regelhaft kardiovaskuläre Implantate im Rahmen der chirurgischen bzw. interventionellen Therapie zum Einsatz. Hierzu zählen u. a. Shunts, Patches und Okkluder, die aus verschiedenen Implantatmaterialien hergestellt werden. Das Ziel dieser Arbeit bestand darin – basierend auf histologischen Untersuchungen – Unterschiede bzw. Gemeinsamkeiten bezüglich der Biokompatibilität nicht-metallischer Implantatmaterialien zu prüfen, da eine bewusste Materialauswahl kardiovaskulärer Implantate zur Therapie angeborener Herzfehler zu besseren Langzeitergebnissen der Implantate beitragen kann. Untersucht wurden Implantate, die im Rahmen von Korrekturoperationen entnommen wurden und anschließend im Forschungslabor für Pädiatrische Kardiologie und Intensivmedizin der Universitätsmedizin Göttingen ausgewertet wurden: Shunts aus PTFE (n = 21, durchschnittliche Implantationszeit: 18 Monate), Patches aus PTFE (n = 13, durchschnittliche Implantationszeit: 247 Monate) und Polyester (n = 4, durchschnittli¬che Implantationszeit: 321 Monate) sowie Okkluder aus PTFE (n = 3, durchschnittliche Implantationszeit: 74 Monate), Polyester (n = 9, durchschnittliche Implantationszeit: 30 Monate) und PVA (n = 2, durchschnittliche Implantationszeit: 23 Monate). Zur Herstellung histologischer Präparate wurden metallhaltige Implantate (Okkluder) sowie solche mit bereits makroskopisch sichtbarer Verkalkung in Methylmethacrylat-Kunstharz eingebettet und anschließend gesägt und geschliffen, sodass sie lichtmikroskopisch ausgewertet werden konnten. Die anderen Implantate wurden in Paraffin eingebettet und geschnitten. Neben konventionellen Färbungen zur Übersicht und Darstellung von Verkalkungen wurden immunhistochemische Färbungen eingesetzt. Unabhängig vom Implantatmaterial konnte regelhaft eine endothelialisierte und neovaskularisierte Pseudointima, hauptsächlich am ehesten aus Myofibroblasten und Fibroblasten bestehend, dargestellt werden. Das im Implantatmaterial neu gebildete Gewebe bestand hauptsächlich aus Fibroblasten und war neovaskularisiert. Implantatassoziierte, chronische Entzündungsreaktionen – getragen durch Makrophagen und Lymphozyten – sowie Fremdkörperreaktionen – getragen durch FKR – waren bei den Polyester- und PVA-Implantaten stärker ausgeprägt als bei den PTFE-Implantaten. Verkalkungen in Pseudointima- und Implantatgewebe wurden bei den Polyester-Implantaten ab einer Implantationszeit von 3 Jahren und 4 Monaten, bei den PTFE-Implantaten ab einer Implantationszeit von 5 Jahren und 10 Monaten beobachtet. Die durch Polyester hervorgerufene, stärker ausgeprägte Entzündungsreaktion ist als Ursache der zu einem früheren Zeitpunkt einsetzenden Verkalkung von Polyester-Implantaten anzusehen. Während bei den Polyester-Implantaten häufig eher ungleichmäßig verteilte und unregelmäßig geformte, punktförmige Verkalkungen bis hin zu kleinen Kalkaggregaten in Pseudointima- und Implantatgewebe vorhanden waren, wiesen die PTFE-Implantate zumeist gleichmäßige, großflächig-konfluierende Verkalkungen auf. Es konnte gezeigt werden, dass bei Implantaten, die Polyester- oder PTFE-Anteile enthal¬ten, mittelfristig mit der Entwicklung von lokalen Verkalkungen zu rechnen ist, die im Langzeitverlauf zu Komplikationen führen können. Dies muss bei der Implantatauswahl beachtet werden. Möglicherweise kann in Zukunft durch die Entwicklung neuartiger Materialien eine Verminderung der Verkalkungstendenz, zum Beispiel durch Biodegra¬dierbarkeit des Implantatmaterials, erreicht werden.

In recent years, electrochemical capacitors have emerged as devices with the potential to enable major advances in electrical energy storage. Electrochemical capacitors (ECs) are akin to conventional capacitors but employ higher surface-area electrodes and thinner dielectrics to achieve larger capacitances. This helps ECs to attain energy densities greater than those of conventional capacitors and power densities greater than those of batteries. Akin to conventional capacitors, ECs also have high cycle-lives and can be charged and discharged rapidly. But ECs are yet to match the energy densities of mid to high-end batteries and fuel cells. On the basis of mechanism involved in the charge-storage process, ECs are classified as electrical double-layer capacitors (EDLCs) or pseudocapacitors. Charge storage in EDLCs and pseudocapacitors is brought about by non-faradaic and faradaic processes, respectively. Faradaic process, such as an oxidation-reduction reaction, involves the transfer of charge between electrode and electrolyte. By contrast, a non-faradaic process does not use a chemical mechanism and charges are distributed on surfaces by physical processes that do not involve any chemical reaction. ECs employ both aqueous and non-aqueous electrolytes in either liquid or solid form, the latter providing the advantages of freedom from leakage of any liquid component, compactness, reliability and large operating potential-window. In the literature, polymer electrolytes are the most widely studied solid electrolytes. Complexation of functional-groups of certain polymers with cations results in the formation of polymer-cation complexes commonly referred to as solid-polymer electrolytes (SPEs). Mixing a polymer with an alkali metal salt dissolved in an organic solvent result in the formation of a polymer gel electrolyte. Organic solvents with low molecular-weights, such as ethylene carbonate and propylene carbonate, employed in polymer gel electrolytes are commonly referred to as plasticizers. When water is used as a plasticizer, the polymer electrolyte is called a polymer hydrogel electrolyte. Part I of the thesis is directed to studies pertaining to Polymer Hydrogel Electrolytes for Electrochemical Capacitors and comprises four sections. After a brief survey of literature on polymer hydrogel electrolytes employed in ECs in Section I.1, Section I.2 of Part I describes the studies on electrochemical capacitors employing cross-linked poly (vinyl alcohol) hydrogel membrane electrolytes with varying perchloric acid dopant concentration. Acidic poly (vinyl alcohol) hydrogel membrane electrolytes (PHMEs) with different perchloric acid concentrations are prepared by cross-linking poly (vinyl alcohol) with glutaraldehyde in the presence of a protonic acid acting as a catalyst under ambient conditions. PHMEs are characterized by scanning electron microscopy and temperature-modulated differential scanning calorimetry in conjunction with relevant electrochemical techniques. An optimised electrochemical capacitor assembled employing PHME in conjunction with black pearl carbon (BPC) electrodes yields a maximum specific capacitance value of about 96 F g-1, phase angle value of about 79o and a discharge capacitance value of about 88 F g-1. Section I.3 of Part I describes the studies on cross-linked poly (vinyl alcohol)/ploy (acrylic acid) blend hydrogel electrolytes for electrochemical capacitors. Acidic poly (vinyl alcohol)/poly (acrylic acid) blend hydrogel electrolytes (BHEs) have been prepared by cross-linking poly (vinyl alcohol)/poly (acrylic acid) blend with glutaraldehyde in presence of perchloric acid. These acidic BHEs have been treated suitably to realize alkaline and neutral BHEs. Thermal characteristics and glass-transition behavior of BHEs have been followed by differential scanning calorimetry. Ionic conduction in acidic BHEs has been found to take place by Grötthus-type mechanism while polymer segmental motion mechanism is predominantly responsible for ion motion in alkaline and neutral BHEs. Ionic conductivity of BHEs has been found to range between 10-3 and 10-2 S cm-1 at 298 K. Electrochemical capacitors assembled with acidic PVA hydrogel electrolyte yield a maximum specific capacitance of about 60 and 1000 F g-1 with BPC and RuOx.xH2O/C electrodes, respectively. Section I.4 of Part I describes the studies on gelatin hydrogel electrolytes and their application to electrochemical capacitors. Gelatin hydrogel electrolytes (GHEs) with varying NaCl concentrations have been prepared by cross-linking an aqueous solution of gelatin with aqueous glutaraldehyde under ambient conditions, and characterized by scanning electron microscopy, temperature-modulated differential scanning calorimetry, cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic chronopotentiometry. Glass transition temperatures for GHEs range between 340 and 377 K depending on the dopant concentration. Ionic conductivity behavior of GHEs is studied with varying concentrations of gelatin, glutaraldehyde and NaCl, and conductivity values are found to vary between 10-3 and 10-1 S cm-1 under ambient conditions. GHEs have a potential window of about 1 V with BPC electrodes. The ionic conductivity of pristine and 0.25 N NaCl-doped GHEs follows Arrhenius behavior with activation energy values of 1.9×10-4 and 1.8×10-4 eV, respectively. Electrochemical capacitors employing GHEs in conjunction with black pearl carbon electrodes are assembled and studied. Optimal values for capacitance, phase angle, and relaxation time constant of about 81 F g-1, 75o, and 0.03 s are obtained for 3 M NaCl-doped GHE, respectively. EC with pristine GHE exhibits continuous cycle life for about 4.3 h as against 4.7 h for the electrochemical capacitor with 3 M NaCl-doped GHE. Unlike electrochemical capacitors, fuel cells do not store the charge internally but instead use a continuous supply of fuel from an external storage tank. Thus, fuel cells have the potential to solve the most challenging problem associated with the electrochemical capacitors, namely their limited energy-density. A fuel cell is an electrochemical power source with advantages of both the combustion engine and the battery. Like a combustion engine, a fuel cell will run as long as it is provided with fuel; and like a battery, fuel cells convert chemical energy directly to electrical energy. As an electrochemical power source, fuel cells are not subjected to the Carnot limitations of combustion (heat) engines. A fuel cell operates quietly and efficiently and, when hydrogen is used as a fuel, it generates only power and potable water. Thus, a fuel cell is a so called ‘zero-emission engine’. In the past, several fuel cell concepts have been tested in various laboratories but the systems that are being potentially considered for commercial developments are: (i) Alkaline Fuel Cells (AFCs), (ii) Phosphoric Acid Fuel Cells (PAFCs), (iii) Polymer Electrolyte Fuel Cells (PEFCs), (iv) Solid-Polymer-Electrolyte-Direct Methanol Fuel Cells (SPE-DMFCs), (v) Molten Carbonate Fuel Cells (MCFCs) and (vi) Solid Oxide Fuel Cells (SOFCs). Among the aforesaid systems, PEFCs that employ hydrogen as fuel are considered attractive power systems for quick start-up and ambient-temperature operations. Ironically, however, hydrogen as fuel is not available freely in the nature. Accordingly, it has to be generated from a readily available hydrogen carrying fuel such as natural gas, which needs to be reformed. But, such a process leads to generation of hydrogen with some content of carbon monoxide, which even at minuscule level is detrimental to the fuel cell performance. Pure hydrogen can be generated through water electrolysis but hydrogen thus generated needs to be stored as compressed / liquefied gas, which is cost-intensive. Therefore, certain hydrogen carrying organic fuels such as methanol, ethanol, propanol, ethylene glycol, and diethyl ether have been considered for fuelling PEFCs directly. Among these, methanol with a hydrogen content of about 13 wt. % (specific energy = 6.1 kWh kg-1) is the most attractive organic liquid. PEFCs using methanol directly as fuel are referred to as SPE-DMFCs. But SPE-DMFCs suffer from methanol crossover across the polymer electrolyte membrane, which affects the cathode performance and hence the cell performance during its operation. SPE-DMFCs also have inherent limitations of low open-circuit-potential and low electrochemical-activity. An obvious solution to the aforesaid problems is to explore other promising hydrogen carrying fuels such as sodium borohydride, which has a hydrogen content of about 11 wt. %. Such fuel cells are called direct borohydride fuel cells (DBFCs). Part II of the thesis includes studies on direct borohydride fuel cells and comprises three sections. After a brief introduction to DBFCs in section II.1, Section II.2 describes studies on an alkaline direct borohydride fuel cell with hydrogen peroxide as oxidant. A peak power density of about 150 mW cm-2 at a cell voltage of 540 mV could be achieved from the optimized DBFC operating at 70oC. Section II.3 describes studies on poly (vinyl alcohol) hydrogel membrane as electrolyte for direct borohydride fuel cells. This DBFC employs a poly (vinyl alcohol) hydrogel membrane as electrolyte, an AB5 Misch metal alloy as anode, and a gold-plated stainless steel mesh as cathode in conjunction with aqueous alkaline solution of sodium borohydride as fuel and aqueous acidified solution of hydrogen peroxide as oxidant. The performance of the PHME-based DBFC in respect of peak power outputs, ex-situ cross-over of oxidant, fuel, anolyte and catholyte across the membrane electrolytes, utilization efficiencies of fuel and oxidant as also cell performance durability under ambient conditions are compared with a similar DBFC employing a Nafion®-117 membrane electrolyte (NME). Peak power densities of about 30 and 40 mW cm-2 are observed for the DBFCs with PHME and NME, respectively. The PHME and NME-based DBFCs exhibit cell potentials of about 1.2 and 1.4 V, respectively, at a load current density of 10 mA cm-2 for 100 h. Publications of Nurul Alam Choudhury 1. Gelatin hydrogel electrolytes and their application to electrochemical supercapacitors, N. A. Choudhury, S. Sampath, and A. K. Shukla, J. Electrochem. Soc., 155 (2008) A74. 2. Cross-linked polymer hydrogel electrolytes for electrochemical capacitors, N. A. Choudhury, A. K. Shukla, S. Sampath, and S. Pitchumani, J. Electrochem. Soc., 153 (2006) A614. 3. Hydrogel-polymer electrolytes for electrochemical capacitors: an overview, N. A. Choudhury, S. Sampath, and A. K. Shukla, Energy and Environmental Science (In Press). 4. Cross-linked poly (vinyl alcohol) hydrogel membrane electrolytes with varying perchloric acid dopant concentration and their application to electrochemical capacitors, N. A. Choudhury, S. Sampath, and A. K. Shukla, J. Chem. Sc. (Submitted) 5. An alkaline direct borohydride fuel cell with hydrogen peroxide as oxidant, N. A. Choudhury, R. K. Raman, S. Sampath, and A. K. Shukla, J. Power Sources, 143 (2005) 1. 6. Poly (vinyl alcohol) hydrogel membrane as electrolyte for direct borohydride fuel cells, N. A. Choudhury, S. K. Prashant, S. Pitchumani, P. Sridhar, and A. K. Shukla, J. Chem. Sc. (Submitted). 7. A phenyl-sulfonic acid anchored carbon-supported platinum catalyst for polymer electrolyte fuel cell electrodes, G. Selvarani, A. K. Sahu, N. A. Choudhury, P. Sridhar, S. Pitchumani, and A. K. Shukla, Electrochim. Acta, 52 (2007) 4871. 8. A high-output voltage direct borohydride fuel cell, R. K. Raman, N. A. Choudhury, and A. K. Shukla, Electrochem. Solid-State Lett., 7 (2004) A 488. 9. Carbon-supported Pt-Fe alloy as a methanol-resistant oxygen-reduction catalyst for direct methanol fuel cells, A. K. Shukla, R. K. Raman, N. A. Choudhury, K. R. Priolkar, P. R. Sarode, S. Emura, and R. Kumashiro, J. Electroanal. Chem., 563 (2004) 181.

Les vésicules géantes unilamellaires (GUV) permettent d'étudier efficacement les interactions entre les lipides et les peptides. Dans ce manuscrit, il a été montré que les interactions attractives lipides-peptides sont supprimées par l'attachement de polypeptides de type élastine (ELP) sur des peptides riches en arginine et peuvent être modulées par l'auto-assemblage en micelles ainsi que par le nombre de groupements arginine dans la séquence des peptides capables de pénétrer les cellules. De plus, une nouvelle méthode pour former des GUV à partir de systèmes complexes en seulement quelques minutes a été développée. Cette méthode est basée sur le gonflement d'un film de PVA sous une bicouche lipidique. Elle supprime la dégradation des molécules pendant la formation des GUV de lipides synthétiques, tels que des glycolipides et des phospholipides portant des groupements amides, où les méthodes traditionnelles ne réussissent pas à produire des vésicules non endommagées.

It was found that a significant improvement of mechanical properties of CFRPs can be achieved by the adjustment of the matrix properties such as toughness and CF/matrix adhesion via the chemical modification, as well as the physical modification by a small amount of cheap and environment-friendly nano fibers. Based on investigation of fracture mechanisms at macro/micro scale, the effects of matrix properties and nano fiber on the mechanical properties of CFRP have been discussed. Subsequently, the relationship has been characterized by a numerical model to show how to modulate the parameters of the matrix properties to achieve excellent fatigue properties of CFRP. / 博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University

No description available.

<p></p><p>This doctoral dissertation takes the reader through a journey where applied shear rheology and flow-velocimetry are used to understand the mesoscopic factors that control the flow behavior of three microstructured fluids. Three individual protocols that measure relative physical and mechanical properties of the flow are developed. Each protocol aims to advance the particular transformation of novel soft materials into a commercial product converging in the demonstration of the real the chemical, physical and thermodynamical factors that could potentially drive their successful transformation. </p> <p> </p> <p>First, this dissertation introduces the use of rotational and oscillatory shear rheometry to quantify the solvent evaporation effect on the flow behavior of polymer solutions used to fabricate isoporous asymmetric membranes. Three different A-B-C triblock copolymer were evaluated: polyisoprene-<i>b</i>-polystyrene-<i>b</i>-poly(4-vinylpyridine) (ISV); polyisoprene-<i>b</i>-polystyrene-<i>b</i>-poly(<i>N</i>,<i>N</i>-dimethylacrylamide) (ISD); and polyisoprene-<i>b</i>-polystyrene-<i>b</i>-poly(<i>tert</i>-butyl methacrylate) (ISB). The resulting evaporation-induced microstructure showed a solution viscosity and film viscoelasticity strongly dependent on the chemical structure of the triblock copolymer molecules. </p> <p> </p> <p>Furthermore, basic shear rheometry, flow birefringence, and advanced flow-velocimetry are used to deconvolute the flow-microstructure relationships of concentrated surfactant solutions. Sodium laureth sulfate in water (SLE₁S) was used to replicate spherical, worm-like, and hexagonally packed micelles and lamellar structures. Interesting findings demonstrated that regular features of flow curves, such as power-law shear thinning behavior, resulted from a wide variety of experimental artifacts that appeared when measuring microstructured fluids with shear rheometry.</p> <p> </p> <p>Finally, the successful integration of shear rheometry to calculate essential parameters to be used in a cost-effective visualization technique (still in development) used to calculate the dissolution time of polymers is addressed. The use of oscillatory rheometry successfully quantify the viscoelastic response of polyvinyl alcohol (PVA) solutions and identify formulations changes such as additive addition. The flow behavior of PVA solutions was correlated to dissolution behavior proving that the developed protocol has a high potential as a first screening tool.</p><br><p></p>