Le but de ce projet est de concevoir un nouveau type d'étiquette ‘écologique', n'utilisant pas de dorsale siliconé. Ainsi, la couche d'adhésif est remplacée par une couche de microcapsules d'adhésif. Ces microcapsules doivent avoir une paroi suffisamment étanche et résistante pour envelopper l'adhésif et ne pas se rompre lors des étapes de fabrication du produit. Par contre, elles doivent céder sous l'effet d'une pression et libérer l'adhésif au moment de leur utilisation. Dans un premier temps, 3 adhésifs en émulsion aqueuse ont été caractérisés en vue de leur microencapsulation. Par la suite, un adhésif a été sélectionné et encapsulé par coacervation (avec des biomatériaux comme carapace) et par polymérisation in situ aminoplaste. Ensuite, 2 autres procédés d'encapsulation d'adhésif réalisés au LAGEP (le spray-drying et le spray-cooling) ont été comparés avec les 2 techniques précédentes. Les capsules produites par spray-cooling, les plus adhésives, ont permis la formulation d'un bain d'enduction en vue d'un couchage des capsules à l'aide d'une barre de Meyer, et par procédé sérigraphique. La compatibilité de ces microcapsules avec le procédé de fabrication d'une étiquette autoadhésive classique, sur une rotative d'impression flexographique, a été montrée. Les caractéristiques finales du produit ainsi fabriqué (adhésion, pression d'application) ont été comparées avec celles de différents produits autoadhésifs industriels (étiquette, enveloppe et timbre). / The main objective of this investigation is to prepare innovative silicone liner-free labels. It can be achieved by the adhesive ‘self protection', thanks to its incorporation into microcapsules. This allows the preparation of ‘dry labels' gluing under the application of a pressure, which induces the rupture of the microcapsules, thus releasing the core material, a pressure sensitive adhesive. The first step was to analyse 3 water-based PSA in view of their encapsulation. Then, the most suitable adhesive was microencapsulated by coacervation (using biopolymer as shell) and by in situ polymerisation. Two other encapsulation processes (spray-cooling and spray-drying), were also carried out at the LAGEP and were compared with the 2 former processes. Coating colour formulations were prepared with spray-cooling microcapsules (the most adhesive ones). Coating trials were carried out with a Meyer rod, and by screen printing. Compatibility between microcapsules and the label making process, using a flexographic printing press, was determined. Finally, the mains characteristics of the prepared innovative products (adhesion, application pressure) were compared to industrial self-adhesive homologues, and found that they could be suitable for the preparation of silicon liner-free envelops and stamps.

No description available.

No description available.

La necesidad de refuerzo estructural en una infraestructura existente puede venir motivada por la aparición de nuevos condicionantes de uso o por la degradación de los materiales. Desde finales de los años sesenta, la técnica del refuerzo mediante la adhesión de platabandas metálicas se ha llevado a la práctica como alternativa a otros métodos de refuerzo tradicionales. Sin embargo, las platabandas metálicas presentan algunas desventajas, como son su peso y su posible corrosión por agentes atmosféricos, que pueden solventarse sustituyéndolas por laminados de polímeros reforzados con fibras (FRP). Estos materiales poseen relaciones resistencia/peso y rigidez/peso mayores que el acero, facilitando su colocación, reduciendo costes y plazos de ejecución.En numerosos estudios empíricos se observa como la aplicación de laminados encolados puede resultar en una rotura frágil que conduce al desprendimiento prematuro del refuerzo antes de alcanzar la carga última.El principal objetivo de este trabajo es el desarrollo de un método simple y efectivo para dimensionar y comprobar el refuerzo de estructuras existentes con laminados adheridos de tal forma que se eviten los modos prematuros de rotura que conducen al desprendimiento del laminado. Se ha dedicado especial atención a la transferencia de tensiones de laminado a hormigón que resulta el punto clave del correcto comportamiento de este tipo de refuerzo.En el Capítulo 2, tras una revisión histórica de las líneas de investigación existentes, experimentales y teóricas, se ha evaluado mediante una base de datos experimental la fiabilidad de los modelos teóricos existentes para pronosticar y prevenir los modos de rotura prematuros antes mencionados. Esta base de datos experimental incluye resultados de la literatura existente y de una campaña experimental llevada a cabo por el autor en el Laboratorio de Tecnología de Estructuras de la Universidad Politécnica de Cataluña.Para resolver las deficiencias de los modelos teóricos existentes, en el Capítulo 3, se ha aplicado la teoría de la Mecánica de Fractura No Lineal a un caso de corte puro para modelizar el comportamiento de la interfase y sus roturas prematuras. Se han obtenido las distribuciones de tensiones en la interfase y en el laminado junto a la fuerza máxima transferida en función de tres parámetros (energía de fractura, máxima tensión tangencial y deslizamiento asociado a dicha tensión).La formulación de un caso de corte puro se ha extendido a un caso general de una viga bajo cargas transversales en el Capítulo 4. Se ha estudiado la evolución del desprendimiento del laminado en dos casos específicos: un elemento entre dos fisuras contiguas, y un elemento entre el extremo del laminado y la siguiente fisura. Se han obtenido las distribuciones de tensiones para las distintas fases del proceso. Cabe mencionar que la fuerza transferida entre dos fisuras alcanza su máximo valor cuando la tensión tangencial máxima llega a la fisura menos cargada. En este instante, ya se puede haber iniciado o no la formación de una macrofisura. El elemento entre el extremo del laminado y la siguiente fisura es similar al caso de corte puro.Las distribuciones de tensiones presentadas en el Capítulo 4 nos ayudan a comprender el comportamiento de un elemento reforzado con laminados adheridos en su cara traccionada, sin embargo, resultan complejas en la práctica. En el Capítulo 5 se describe un nuevo método de dimensionamiento y verificación basado en la obtención de una relación entre el máximo cortante antes de que se produzca el desprendimiento prematuro del refuerzo y el momento aplicado. Esta relación está asociada a la fuerza máxima transferida entre fisuras. A partir de la predicción del valor máximo de cortante, se verifica el desprendimiento del extremo del laminado evaluando la fuerza transferida entre dicho punto y la siguiente fisura. Se ha verificado la fiabilidad de esta propuesta mediante la base de datos de ensayos a flexión.Finalmente, en el Capítulo 6 se resumen las principales conclusiones del trabajo presentado en esta tesis y se sugieren futuras líneas de investigación. / The strengthening of aging infrastructures is in most cases required because of the necessity for increased levels of service loads or because of the degradation of structural materials. The technique of strengthening by externally bonding steel plates has been in practice since the late 1960's. However, steel plates present some disadvantages in terms of weight and corrosion that can be solved by replacing them with fiber reinforced polymer (FRP) laminates. FRP laminates provide benefits such as high strength-to-weight and stiffness-to-weight ratios, corrosion resistance as well as reduced installation costs due to their easy-handling.Existing experimental work has shown that the application of externally bonded laminates can result in a catastrophic brittle failure in the form of a premature debonding of the laminate before reaching the design load.The main aim of this research has been the development of a simple effective method to design and verify the strengthening of an existing structure with an externally bonded plate while preventing the premature peeling failure that causes the laminate to debond. Special attention has been drawn on to transfer of stresses from laminate to concrete through the interface, which is the main key in the correct performance of externally reinforced concrete structures.After a historical overview of the existing experimental and theoretical lines of research, the suitability of using existing theoretical models to forecast and prevent peeling failures is evaluated in Chapter 2 by means of an experimental bending test database. This database includes results from the existing literature and results from an experimental program conducted by the author at the Structural Technology Laboratory of the Technical University of Catalonia.To solve the weaknesses of the existing theoretical models, in Chapter 3, Non-Linear Fracture Mechanics theory is applied in a pure shear case to model the interface behavior and its premature failures. The stress distributions, together with the maximum transferred force are obtained as a function of three model parameters (the fracture energy, the maximum shear stress and the sliding associated to this stress).The formulae of a pure shear specimen are then extended to a general case of a beam under transverse loads in Chapter 4. For this purpose, the evolution of the debonding process is studied for two specific cases: a beam element between two cracks, and a beam element between the laminate end and the nearest crack. The stress distributions are obtained for the different stages observed in the debonding process. A specific highlight observed was that the transferred force between cracks is at maximum when the maximum shear stress reaches the less-loaded crack. In this instance, a macrocrack may or may not have already initiated. Another point observed is related to the beam element between the laminate end and the nearest crack, which is similar to the pure shear specimen.The stress distributions derived in Chapter 4 allow us to understand the behavior of an externally reinforced element, but are awkward for design purposes. Chapter 5 describes both a new design and verification method based on a maximum shear force-bending moment relationship associated to the theoretical maximum transferred force between two consecutive cracks before peeling occurs. After calculating the predicted value for the maximum shear force from the peeling relationship, the developed method verifies the debonding at the laminate end by checking the transferred force between the laminate end and the first crack in the laminate. The reliability of this proposal is verified by means of the assembled bending test database.Finally, the main conclusions drawn from the work presented in this dissertation are summarized in Chapter 6. Future work and research lines are suggested as well.

Adhesively bonded joints have been investigated for several decades. In most analytical studies, the Bernoulli-Euler beam theory is employed to describe the behaviour of adherends. In the current work, three analytical models are developed for adhesively bonded joints using the Timoshenko beam theory for elastic material and a Bernoulli-Euler beam model for viscoelastic materials. One model is for the peeling test of an adhesively bonded joint, which is described using a Timoshenko beam on an elastic foundation. The adherend is considered as a Timoshenko beam, while the adhesive is taken to be a linearly elastic foundation. Three cases are considered: (1) only the normal stress is acting (mode I); (2) only the transverse shear stress is present (mode II); and (3) the normal and shear stresses co-exist (mode III) in the adhesive. The governing equations are derived in terms of the displacement and rotational angle of the adherend in each case. Analytical solutions are obtained for the displacements, rotational angle, and stresses. Numerical results are presented to show the trends of the displacements and rotational angle changing with geometrical and loading conditions. In the second model, the peeling test of an adhesively bonded joint is represented using a viscoelastic Bernoulli-Euler beam on an elastic foundation. The adherend is considered as a viscoelastic Bernoulli-Euler beam, while the adhesive is taken to be a linearly elastic foundation. Two cases under different stress history are considered: (1) only the normal stress is acting (mode I); and (2) only the transverse shear stress is present (mode II). The governing equations are derived in terms of the displacements. Analytical solutions are obtained for the displacements. The numerical results show that the deflection increases as time and temperature increase. The third model is developed using a symmetric composite adhesively bonded joint. The constitutive and kinematic relations of the adherends are derived based on the Timoshenko beam theory, and the governing equations are obtained for the normal and shear stresses in the adhesive layer. The numerical results are presented to reveal the normal and shear stresses in the adhesive.

In recent decades, a significant research has been carried out towards understanding the behaviour of plated beam. Initially designed to achieve a desired capacity, the plated beams prematurely fail in undesirable modes of failure, such as debonding and peeling. The uncertainty related with such modes of failure poses a real challenge towards quantifying them. This field is far from being clearly understood. Therefore, an attempt is made in this thesis to accurately predict the behaviour of adhesively plated beams.

Cette thèse concerne l'étude de la dynamique instable du front de détachement d'un ruban adhésif lors de son pelage à vitesse constante depuis un substrat plan. Nous avons en particulier mis en évidence le rôle essentiel de l'inertie du ruban sur cette instabilité.Dans un premier temps, nous avons réalisé une étude expérimentale des différentes dynamiques macroscopiques du front, observé par imagerie rapide, en fonction de la vitesse et de l'angle de pelage. Un régime constitué d'oscillations sinusoïdales en vitesse a alors été mis en évidence à la transition entre le pelage régulier et l'instabilité de stick-slip. Un modèle théorique, prenant en compte l'inertie du ruban, et sa résolution numérique ont permis de retrouver les différentes dynamiques observées, ainsi que les caractéristiques de ces oscillations.D'autre part, l'instabilité de stick-slip microscopique, récemment découverte, a également été étudiée. Nous avons caractérisé l'amplitude des avancées saccadées en fonction de la vitesse et de l'angle de pelage, mais également des propriétés physiques du ruban (masse et module de flexion). Son évolution avec ces différents paramètres est en accord avec une modélisation dynamique du front de détachement, couplant énergie de courbure et énergie cinétique du ruban. / This thesis presents the study of the unstable dynamics of the detachment front of an adhesive tape peeled at constant velocity from a flat surface. We could specifically highlight the essential role of the ribbon inertia on this instability.On one hand, we have performed an experimental study of the different front dynamics at macroscopic scales, observed by fast imaging, as a function of the peeling velocity and peeling angle. We could find a novel dynamical regime with sinusoidal oscillations of the detachment front velocity at the transition between regular peeling and stick-slip motion. A theoretical model taking into account the ribbon inertia, and its numerical resolution allow to explain the different dynamics observed, and furthermore, the characteristics of those velocity oscillations.On the other hand, the recently discovered microscopic stick-slip instability has also been studied. We have characterized the amplitude of the corresponding slips as a function of the peeling velocity and peeling angle, but also, as a function of the ribbon properties (mass and bending modulus). We show that a dynamical model coupling bending and kinetic energy of the ribbon can explain its evolution with these different parameters.

Master of Science / Food Science Institute - Animal Sciences & Industry / Fadi M. Aramouni / Sweet potatoes are a significant crop and are popular among consumers, particularly as french fries. Because the processing steps of making white potato french fries may be detrimental to the quality of a sweet potato fry, it is important to understand the impact of processing on quality and consumer acceptability. The variety of sweet potatoes can affect the texture, appearance, and consumer preference. Peeling processes have evolved from harsh lye treatments to more quick and efficient methods such as steam peeling. Blanching is one of the most important steps because it deactivates enzymes, including polyphenol oxidase and amylases, that affect texture and appearance. While hot water blanching is used by majority of french fry manufacturers, novel techniques like microwave blanching may be similarly effective and less detrimental to the texture and nutritional composition. Time and temperature of the blanching method can affect the texture and flavor by weakening cell walls and leaching sugars. Drying of sweet potato fries prepares the product prior to frying. Drying drives moisture off and allows the starch on the surface of the fries to gelatinize. Many types of dryers, including vacuum, hot air, and fluidized bed, have been evaluated for the rate of moisture loss and final product texture. Drying should not be done too quickly because case hardening will occur and make the product have a tough and chewy bite. Frying uses oil at elevated temperatures to develop color, flavor, and a crispy external texture. The type of oil, oil temperature, and time of frying will affect the finished product attributes. Low oil temperature may lead to higher oil uptake into the sweet potato fries. Vacuum frying compared to deep fat frying can create sweet potato fries with less darkening and less oil uptake, but this method would be difficult in large scale manufacturing. Opportunities in creating high quality sweet potato french fries are directly related to consumer acceptability and manufacturing capability.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Um dos maiores problemas atuais da indÃstria de beneficiamento de castanha de caju, sÃo as amÃndoas que necessitam de re-despeliculagem, as amÃndoas do tipo âdurÃoâ, despeliculadas manualmente, ou com vapor convencional, tendo como inconvenientes a baixa produtividade de raspagem e o escurecimento das amÃndoas, fatores depreciativos de preÃo. Para solucionar esse problema, inicialmente foram realizados em nÃvel de laboratÃrio, ensaios de tratamento de amÃndoas despeliculadas e com pelÃculas de diÃmetro mÃdio à = 1,68 mm, com vapores provenientes de soluÃÃes de Ãcido tartÃrico (1%; 2% e 3%), Ãcido mÃlico (1%; 3% e 5%), cloreto de potÃssio (1%, 2% e 3%) e Ãgua nos tempos de exposiÃÃo de 1,2, 3, 4 e 5 minutos. Foram quantificados nos condensados dos vapores, provenientes do tratamento da pelÃcula, os compostos fenÃlicos totais e pigmentos hidrossolÃveis. Os compostos fenÃlicos totais tambÃm foram quantificados nos vapores apÃs os tratamentos das amÃndoas despeliculadas. Nas amÃndoas despeliculadas foram determinados a concentraÃÃo de hidroximetilfurfural (HMF) e a cor instrumental. Neste estudo, alÃm de quantificar os constituintes jà citados, foi de extrema importÃncia o entendimento acerca da forma como ocorre o escurecimento na superfÃcie das amÃndoas, via reaÃÃo de Maillard e pela interaÃÃo dos pigmentos extraÃdos com esses vapores. Os resultados mostraram que os menores teores de pigmentos solÃveis, fenÃlicos totais extraÃdos da pelÃcula e a menor formaÃÃo de hidroximetilfurfural nas amÃndoas ocorreram nos tratamentos com Ãcido tartÃrico 1,0% - 1,0 minuto; Ãcido mÃlico - 1% - 1,0 minuto; cloreto de potÃssio 2,0% - 1 minuto e Ãgua - 1,0 minuto. Foi avaliado tambÃm o despeliculamento e a quebra em escala industrial nas amÃndoas durÃo com pelÃcula aplicando esses vapores citados, nos tempos e concentraÃÃes mencionados, mostrando os seguintes valores para as porcentagens de despeliculagem e quebra, respectivamente: Ãcido mÃlico: 50,24 - 28,37; Ãcido tartÃrico: 56,78 - 20,99; cloreto de potÃssio: 56,52 - 23,15 e Ãgua: 50,43 - 24,12. A anÃlise colorimÃtrica das amÃndoas tratadas com vapor de Ãcido tartÃrico a 1% - 1 min. mostrou que esta fonte de vapor, foi a que apresentou melhores resultados em todos os parÃmetros (L*, a* e b*), quando comparadas as amÃndoas padrÃo tipo 01 tratadas com vapor de Ãgua. Os resultados mostraram ainda que à mais vantajoso usar vapor de Ãcido tartÃrico em vez de vapor de Ãgua para aumentar o rendimento de despeliculagem e reduzir a quebra das amÃndoas de castanha de caju tipo âdurÃoâ. / One of the biggest challenges that faces the cashew nut processing industries today, is the kernels that needs to peel again, called durao kernels, manually peeled- with a low peeling yield or peeled with conventional water steam - which causes a noticeable browning, decreasing its commercial value. To solve this problem, were performed initially on a laboratory scale, peeled kernels and skin (à = 1,68 mm) from kernels were treated with steams from tartaric acid 1,0;2,0;3,0% ; malic acid 1,0;3,0;5,0 % ; potassium chloride 1,0;2,0 3,0% and water during 1,2,3,4 and 5 minutes. Was measured the condensed steam, from treatment of the skin, total phenolics and water soluble pigments. The total phenolics were also measured in the steams after treatment of peeled kernels. In kernel peeled, concentration hydroxymethylfurfural (HMF) and instrumental color, was determined. In this study, in addition to measuring the constituents already mentioned, was extremely important to the understanding of how browning occurs on the surface of kernels, the Maillard reaction and the interactions of the extracted pigments with their steams. The results showed that the lowest concentration of soluble pigments, total phenolics extracted from the skin and less formation of hydroxymethylfurfural in kernels occurred in treatment with tartaric acid 1,0% - 1,0 minute; malic acid 1,0% - 1,0 minute; potassium chloride 2,0% - 1,0 minute and water - 1,0 minute. The peeled and breaking on an industrial scale in kernels durao with skin applying these steams cited in times and concentrations mentioned, showing the following values for the percentages of peeling and breaking, was determined respectively - malic acid: 50,24 - 28,37; tartaric acid: 56,78 - 20,99; potassium chloride: 56,52 - 23,15 and water: 50,43 - 24,12. From the peeled kernel colorimetric analysis (L*, a*, b*) after treatments with the four steams in the times above mentioned, tartaric acid 1,0% - 1,0 minute showed the best values when compared with the colour parameter of the kernel exportation 01- standard. The results still showed that is more profitable to use tartaric acid steam instead of water steam to increase peeling yield and reduce kernel durao breaking.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-03-02T11:27:16Z No. of bitstreams: 1 mariacristinacardosodemendonca.pdf: 8315524 bytes, checksum: 5cb09e7f3009f401bfe32a402cc10858 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-03-03T14:47:04Z (GMT) No. of bitstreams: 1 mariacristinacardosodemendonca.pdf: 8315524 bytes, checksum: 5cb09e7f3009f401bfe32a402cc10858 (MD5) / Made available in DSpace on 2016-03-03T14:47:04Z (GMT). No. of bitstreams: 1 mariacristinacardosodemendonca.pdf: 8315524 bytes, checksum: 5cb09e7f3009f401bfe32a402cc10858 (MD5) Previous issue date: 2013-08-26 / O peeling de fenol é considerado um importante agente no tratamento do rejuvenescimento facial, porém sua utilização implica em limitações pelo seu grande potencial de efeitos colaterais. Com o avançar de novas técnicas, houve a introdução dos lasers na propedêutica dermatológica, técnica essa mais segura, porém com limitações tanto no pós-operatório quanto no custo de cada tratamento. O presente trabalho propõe uma nova técnica de aplicação do peeling profundo para tratamento do fotoenvelhecimento com o objetivo de avaliar clínica e histopatologicamente a eficácia de uma nova forma de aplicação de fenol 88%, com padrão pontuado. O procedimento foi realizado em ambiente ambulatorial, em pacientes do sexo feminino sobre rugas estáticas e áreas de maior flacidez da face, visando o rejuvenescimento facial, com acompanhamento fotográfico e obtenção de amostras cutâneas para análise histopatológica antes e ao final do tratamento. Essa nova forma de aplicação reduziu consideravelmente o afastamento do paciente de suas atividades habituais, além do baixo custo em relação ao procedimento convencional. De acordo com os resultados, o fenol a 88% aplicado topicamente com técnica pontuada é efetivo no rejuvenescimento cutâneo. Assim, sugerimos que, a partir desta nova proposta, outros estudos sejam realizados para melhor elucidar os mecanismos de ação do fenol 88%, em grupos maiores de pacientes. / Phenol peeling is considered an important agent in the treatment of facial rejuvenation; however, its use carries limitations due to its high potential for side effects. With the advance of new techniques, lasers were introduced into the dermatological workup, a technique that is safer, but with limitations both in post-operative terms and in the cost of each treatment. This paper proposes a new deep peeling application technique for the treatment of photoaging, aiming to evaluate, clinically and histopathologically, the efficacy of a new way of applying 88% phenol, using a punctuated pattern. The procedure was performed in an outpatient setting, with female patients, on static wrinkles and high flaccidity areas of the face, aiming for facial rejuvenation. Accompanying photographs and skin samples were taken for histopathological analysis before and after treatment. This new form of application considerably reduced patients' withdrawal from their regular activities, and lowered the cost as well, compared to the conventional procedure. According to the results, 88% phenol applied topically using a punctuated technique is effective in skin rejuvenation. We thus suggest, based on this new proposal, that further studies be conducted to better elucidate the action mechanisms of 88% phenol in larger groups of patients.