O objetivo deste trabalho foi a preparação de um revestimento inteligente com resina epóxi, capaz de autorreparar-se quando o sofre um defeito mecânico. A autorreparação é possibilitada pela presença de microcápsulas, dispersas na resina (revestimento de epóxi sem pigmentos) e que contêm no seu núcleo o agente de autorreparação, o óleo de linhaça. Estas cápsulas foram preparadas por uma emulsão de óleo de linhaça em água para formar micelas e sobre estas uma parede ou casca exterior de poliuréia-formaldeído. Para a avaliação da resistência à corrosão e do efeito de autorreparação do revestimento, chapas de aço carbono foram revestidas e avaliadas pela técnica de espectroscopia de impedância eletroquímica (EIE) em 0.1molL-1 1 NaCl e também foram avaliadas pelo teste acelerado de corrosão em câmara de névoa salina (SSC). Após a cura do revestimento aditivado com as microcápsulas, aplicado sobre placas de aço carbono, as medidas eletroquímicas de impedância foram realizadas em corpos de prova com um defeito mecânico provocado de forma controlada e reprodutível. Uma célula de três eletrodos foi utilizada. Estas medidas foram efetuadas após 0h, 24h e 48h da execução da incisão ou defeito mecânico. Para comparação, as mesmas medidas foram realizadas com as placas pintadas com o revestimento não-aditivado, com a mesma espessura total de 120 m. Os resultados mostraram que as cápsulas foram quebradas e se liberou o óleo de linhaça, reparando a área da incisão o defeito após pelo menos 24 horas de exposição natural ao ar ambiente. Verificou-se que para as placas revestidas sem defeito, os valores de | Z | mantiveram-se elevados. No entanto, o revestimento sem as microcápsulas, após 24 horas, mostrou uma diminuição considerável no valor de módulo de impedância, |Z|. Assim, usando a técnica de EIE foi possível avaliar quantitativamente o mecanismo de autorreparação do revestimento aditivado com microcápsulas que contêm óleo de linhaça. Os ensaios acelerados de corrosão (SSC) mostraram resultados em estreita concordância com os obtidos por EIE. / The aim of this work was the preparation of a smart coating with epoxy resin which is able to repair itself (self-healing effect) after suffering a mechanical defect. Self-healing is possible due to the presence of microcapsules, dispersed in the resin (clear type epoxy coating) and contain in their core the self-healing agent, the linseed oil. These capsules were prepared in an emulsion of linseed oil in water to form micelles and an outer skin or wall of poly(urea-formaldehyde) was formed. For the corrosion resistance and the self-healing effect evaluation of the coating, carbon steel plates were coated and tested by electrochemical impedance spectroscopy technique (EIS) in 0.1molL-1 NaCl solution and by accelerated corrosion test in salt spray chamber (SSC). After curing of the capsules additivated epoxy based clear coating applied on carbon steel plates, electrochemical impedance measurements were performed on plates with a controlled and reproducible mechanical defect. A three-electrode electrochemical cell was used. These measurements were performed after 0h, 24h and 48h of making the incision or mechanical defect. For comparison, the same measurements were performed with the plates painted with a non- capsules additivated clear coating of the same total thickness of 120 m. The results showed that the capsules were broken and released the linseed oil, which indeed have repaired the incision area after at least 24 hours of natural air aging. It was found that for the plates coated without a defect, the values of impedance modulus, |Z|, remained high. However, the coating without the capsules after 24 hours, showed a considerable decrease in |Z|. So, using EIS it was possible to quantitatively assess the mechanism of self-healing of the additivated coating using microcapsules containing linseed oil. The SSC accelerated corrosion tests showed results in close agreement with those obtained by EIS.

In recent years supramolecular chemistry has established as one of the most active fields of science. The most significant feature of supramolecular chemistry is the use of building blocks which reversibly held together by intermolecular forces, electrostatic or H-bonding. Therefore, the synthesis of supramolecular systems using different non-covalent assemblies provides some unique architectures and features which are extremely difficult to be obtained via covalent synthesis. One main application of such influencing supramolecular systems is the preparation of self-healing materials. Among various approaches to self-healing effects, reversible bond formation has become prominent in the last years. To achieve both acceptable mechanical performance and self-healing behaviour from a polymeric material, proper balance between covalent and non-covalent bonding is important. The covalent bonding gives a basic strength to the material while the non-covalent bonding generates self-healing effects in the case of damage. The main aim of this study was to synthesize an organic moiety which is capable of forming supramolecular assemblies in the presence of suitable counterparts, followed by its incorporation on to polymer matrix and investigation of the final properties. For reversible bond forming technique H-bonding is exploited in this work. 4-substituted-2,6-diaminopyridine is selected as the organic moiety as it has a clear DAD (donor-acceptor-donor) structure and thus able to undergo self-association or triple hydrogen bonded complex formation with respective counterparts. Chichibabin reaction was utilised for the synthesis and 4-hydroxy-2,6-diamido pyridine was synthesised as the key compound. Initially different derivatives of 4-hydroxy-2,6 diamino pyridine was synthesized and utilised towards the formation of supramolecular network with a suitable monomeric counterpart. Poly (butadiene-co-maleic anhydride) is used as the base polymer as it has the possibility to introduce non-covalent bonding sites through grafting reactions on the double bonds or on maleic anhydride groups. The free amine group present in the main compound was grafted onto the backbone of poly (butadiene-co-maleic anhydride) via reaction of amine with maleic anhydride group. The main design of supramolecular self-assembly within poly (butadiene-co-maleic anhydride) with a suitable counterpart poly (butadiene-co-maleimide), is prepared and used in this thesis. The miscibility of the two polymers is proven by the presence of a single Tg in the DSC results of the mixture and also by the formation of homogeneous films with no phase separation in AFM. However the formation of hydrogen bonding within the monomer was proven by 1H NMR, IR studies. Further formation of complex between two polymers was established from the results of viscosity. Also the interactions between the complexes exert a distinct influence on the rheological behavior of the blend. Lastly the reversibility of this supramolecular blend was assured by temperature dependent viscosity values. In the final part of this work, bromobutyl rubber (BIIR) is selected as the model elastomer which has vast application in the tire industry; as the inner-liner that holds the air in the tire and also used as rubber stoppers for sealing medicine vials and bottles The bromine functionality can be substituted with an amine group making it more susceptible towards the incorporation of different organic moieties. In this way, the derivative of 2,6-diaminopyridine having a pendant amine group is incorporated in BIIR. As a counterpart uracil is used as its H-bond forming ability with diaminopyridine moieties is well established and supported by different previous research works. The supramolecular network formed between these two monomers help to generate self-healing effects within BIIR rubber. Fig. 2 represents the supramolecular network formed between chains of BIIR. The self-healing effect of the rubber material is examined through the stress-strain experiments where up to 82% healing was observed when heated up to 70 °C. With increasing temperature better healing was observed whereas at room temperature a 40% healing tendency was noticed. It is also interesting to note that the thermal and dynamic mechanical properties of this tailor made self-healing BIIR is identical with sulphur cured conventional BIIR.

<div> <p>The formation of the cracks in concrete materials can shorten the service life of the structure by exposing the steel rebar to the aggressive substances from the external environment. Self-healing concrete can eliminate the crack automatically, which has the potential to replace manual rehabilitation and repairing work. This thesis intends to develop a self-healing fiber-reinforced cementitious composite by the use of internal curing agents, such as lightweight aggregate, zeolite and superabsorbent polymer (SAP). This study has evaluated the crack width control ability of three different types of fiber, polyvinyl alcohol fiber (PVA), Masterfiber Mac Matrix and Strux 90/40 fiber. Mechanical performance and flexural stress-strain behavior of the fiber-reinforced cementitious composite were tested and compared. In order to investigate the feasibility of using internal curing aggregate to enhance autogenous healing performance, two types of porous aggregates, zeolite and lightweight aggregate (LWA), were used as internal curing agents to provide water for the autogenous healing. The pore structure of the zeolite and lightweight aggregate was examined by the scanning electron microscopy (SEM). Two replacement ratios of sand with internal curing aggregates were designed and the healing efficiency was evaluated by the resonant frequency measurement and the optical microscopic observation. To further understand the influence of the internal curing on the designed material, water retention behavior of the bulk sample and the internal curing aggregates was evaluated. Moreover, to study the self-sealing effect of the superabsorbent polymer (SAP), the robustness of the SAP under various environmental conditions was first evaluated. The influence of the superplasticizer, hydration accelerator and fly ash on the absorption behavior of the SAP was investigated by the filtration test and void size analysis. Afterward, the self-sealing performance of the SAP in cement paste was evaluated by a water flow test.</p> <p>The evaluation of three types of fiber indicated that the use of PVA fiber could produce a cementitious composite with stronger mechanical strength and crack width control ability. The result of the autogenous healing evaluation showed that the incorporation of the internal curing aggregates increased the self-healing recovery ratio from 12.6% to over 18%. The internal curing aggregate could absorb and store water during the wet curing and release it when the external water supply is unavailable. The comparison between the two types of internal curing aggregates indicated that finer pores in the internal curing aggregate can lead to a slower water release rate that is capable of continuously supplying water for the autogenous healing. In addition, the SAP was proved to be robust when various content of the additives and fly ash were used. And the self-sealing effect of the SAP is found to be effective in regaining the water tightness of cement paste. The result of this thesis can assist in the design of the fiber-reinforced cementitious composite with self-healing performance in civil engineering.</p> </div> <br>

Bitumen acts as a binding agent in asphalt mixtures where it binds the aggregates together. It is known for its potential to heal small cracks and recover its mechanical properties under the right conditions. Though this self-healing property is known, there is currently a lack of knowledge about the mechanisms that drive the process. To optimize the use of this material for pavement design, the healing ability should be better understood and controlled. In this work, it is investigated how neutron imaging can be used to increase the understanding of the mechanisms behind the self-healing in bitumen. As a first step, the sample size requirement set by the measurement technique was determined. In order to detect micro cracks in bitumen by using this technique, the sample must be sufficiently small to allow neutron transmission. On the other hand, too small samples would complicate the structural analysis of the material since less information would be possible to obtain. Bitumen with different dimensions were scanned with neutrons to determine the maximum sample thickness. This work was followed by evaluating the healing capability of fractured bitumen and mastic samples, by using time series neutron tomography. The studied samples had a varying combination of hydrated lime (HL) filler concentration, crack volume, and contact area between the broken pieces. The data acquired from the time series tomography scans was analyzed using a three-dimensional analysis procedure including denoising, segmentation and volume measurements. From the volumetric analysis, it appeared that the initial crack size and crack shape have a large impact on the healing rate. It was found that bitumen, mastic with 20%, and 30% filler content had a similar healing behavior for relatively small crack volumes. When increasing the content of HL in the mastic, the healing rate decreases exponentially, with a drastic decrease after reaching a filler content of about 30%. / Bitumen fungerar som bindemedel i asfaltsblandningar där det binder ihop stenaggregaten. Bitumen är känd för sin förmåga att läka små sprickor och återfå sina mekaniska egenskaper under rätt förutsättningar. Trots att den självläkande egenskapen är välkänd, råder det idag en brist på kunskap om de mekanismer som ligger bakom denna process. För att optimera användandet av bitumen för vägbeläggningar behövs en bättre förståelse kring denna läkande egenskap. I detta projekt undersöks det hur neutronavbildning kan användas för att öka förståelsen kring de mekanismer som ligger bakom den självläkande egenskapen hos bitumen. Som ett första steg bestämdes provstorlekskravet för denna analysteknik. För att möjliggöra detekteringen av små sprickor i bitumen genom att använda denna teknik måste provmaterialet vara tillräckligt tunt för att neutronerna ska kunna transmitteras genom materialet. Allt för små provstorlekar skulle, å andra sidan, försvåra analysen av materialets struktur då informationen man kan erhålla blir mer begränsad. Bitumen med olika provstorlekar skannades med neutroner för att bestämma den maximala provtjockleken. Därefter analyserades den självläkande förmågan hos brutna bitumen- och bitumenmastixprover med tidsserie neutrontomografi. Prover med olika mängder av kalciumhydroxidfiller i bitumenblandningen, olika storlek på sprickvolymen och kontaktytan mellan de brutna provdelarna studerades. Data erhållna från experimenten användes för att göra en 3-dimensionell analys som inkluderade brusreducering av bilder, segmentering och volymmätningar. Från volymanalyserna konstaterades det att den initiala sprickstorleken och sprickformen har en stor inverkan på läkningstakten. Bitumen, mastix med 20%, och 30% filler-additiv uppvisade liknande läkningsegenskaper för relativt små sprickstorlekar. Vid en ökning av mängden filler material i mastixen minskar läkningstakten exponentiellt, med en drastisk minskning när man passerar en filler-koncentration på runt 30%. / <p>QC 210303</p>

Les opérateurs de réseaux de télécommunications accordent une importance toute particulière à la gestion des pannes. L’implication de l'humain dans la prise de décision et l'analyse d'une quantité énorme d'alarmes et d'informations, ainsi que le caractère réactif des mécanismes de gestion des pannes, ne permettent pas la réactivité nécessaire à une gestion optimale des incidents. Pour pallier ce problème, cette thèse s'intéresse à des mécanismes proactifs qui anticipent les pannes afin d'améliorer l'efficacité de leur gestion. La mise en oeuvre, dans les équipements, de composants autonomes capables d'analyser en permanence l'état de santé du réseau permettrait de fournir une information en temps réel sur le risque de panne, nécessaire au déploiement de nouveaux mécanismes d'autoréparation proactifs. La première partie de cette thèse est donc consacrée à la définition des composants architecturaux indispensables à l'introduction de fonctions d'autoréparation proactives. Dans un deuxième temps, nous étudions et analysons en détail trois mécanismes d'autoréparation proactifs exploitant une information de risque de panne. Le premier mécanisme a pour objectif d'accélérer la convergence des protocoles de routage à état de lien en adaptant la fréquence d'envoi des messages de détection de pannes en fonction du risque de panne. Le deuxième mécanisme modifie dynamiquement les métriques de routage afin de détourner le trafic des équipements risqués et de minimiser l'impact d'une panne sur le trafic. Enfin, le dernier mécanisme s'attache aux dispositifs de protection et de restauration du protocole GMPLS afin d'adapter dynamiquement la consommation des ressources, aux risques encourus / Network providers attach a significant focus to fault-management. Indeed, availability and quality of service are highly important parameters in the competition between networks operators. Tthe involvement of human in the decision making process and the analyzing a huge amount of alarms and information, as well as the reactive nature of fault management mechanisms, do not allow the required reactivity for optimal management of incidents. This thesis focuses on proactive mechanisms which anticipate failures to improve the effectiveness of their management. Indeed, the failures are often preceded by alarms or symptomatic behaviors. Implementation, in equipment, of autonomous components capable of continuously analyzing the network health would enable to provide a real-time risk of failure information, required to deploy new proactive self-healing mechanisms. The first part of this thesis is devoted to the definition of architectural components necessary for the introduction of proactive self-healing functions. Then, in a second step, we study and analyze in detail three self-healing mechanisms exploiting a proactive risk-level of failure information. The first mechanism is designed to accelerate the convergence of link-state routing protocols by adjusting the frequency of sending failure detection messages function of the risk-level. The second mechanism dynamically tunes routing metrics in order to divert traffic flows from risky equipment and to minimize the failure incidence on traffic. Finally, the last proposition is dedicated to the recovery mechanisms of GMPLS protocol by dynamically adapting the resources consumption of recovery to the involved risks

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There is an intense, worldwide effort to develop durable lithium ion batteries with high energy and power densities for a wide range of applications, including electric and hybrid electric vehicles. For improvement of battery technology understanding the capacity fading mechanism in batteries is of utmost importance. Novel electrode material and improved electrode designs are needed for high energy- high power batteries with less capacity fading. Furthermore, for applications such as automotive applications, precise cycle-life prediction of batteries is necessary. One of the critical challenges in advancing lithium ion battery technologies is fracture and decrepitation of the electrodes as a result of lithium diffusion during charging and discharging operations. When lithium is inserted in either the positive or negative electrode, there is a volume change associated with insertion or de-insertion. Diffusion-induced stresses (DISs) can therefore cause the nucleation and growth of cracks, leading to mechanical degradation of the batteries. With different mathematical models we studied the behavior of diffusion induces stresses and effects of electrode shape, size, concentration dependent material properties, pre-existing cracks, phase transformations, operating conditions etc. on the diffusion induced stresses. Thus we develop tools to guide the design of the electrode material with better mechanical stability for durable batteries. Along with mechanical degradation, chemical degradation of batteries also plays an important role in deciding battery cycle life. The instability of commonly employed electrolytes results in solid electrolyte interphase (SEI) formation. Although SEI formation contributes to irreversible capacity loss, the SEI layer is necessary, as it passivates the electrode-electrolyte interface from further solvent decomposition. SEI layer and diffusion induced stresses are inter-dependent and affect each-other. We study coupled chemical-mechanical degradation of electrode materials to understand the capacity fading of the battery with cycling. With the understanding of chemical and mechanical degradation, we develop a simple phenomenological model to predict battery life. On the experimental part we come up with a novel concept of using liquid metal alloy as a self-healing battery electrode. We develop a method to prepare thin film liquid gallium electrode on a conductive substrate. This enabled us to perform a series of electrochemical and characterization experiments which certify that liquid electrode undergo liquid-solid-liquid transition and thus self-heals the cracks formed during de-insertion. Thus the mechanical degradation can be avoided. We also perform ab-initio calculations to understand the equilibrium potential of various lithium-gallium phases.