The epoxy resin mixture is used for wet filament winding load carrying and electrically insulating tubes for high voltage applications. The cured tubes are key parts of the final products which are subject to qualification. The safe function of the products generally depends on low moisture content. Visual inspection is also an important part of the quality inspection which requires some degree of transparency of the cured tubes. To prepare for future material modifications ABB wishes to evaluate the curing characteristics of some recently developed epoxy/hardener systems. The epoxy resin with the formulation E1/H1 is used as reference. Another type of base epoxy resin E2 and toughened epoxy resin E1 (E1T) are included in the study. Three alternative hardeners H2, H3, and H4 were evaluated. This project is to evaluate different alternative epoxy resin formulations that are promising to be used in the ABB products in the future. These alternative epoxy resin formulations and the reference epoxy resin with the formation E1/H1 were prepared to be compared and evaluated in terms of thermal properties, i.e., glass temperature (Tg), the heat of curing and color of cured epoxy resins. The epoxy resins with alternative formulations which shown relative high Tg values were selected to carry out other analysis, ie., mixing ration optimization, the influence of dissolved water on Tg values, degree of curing and water absorption behavior.

Le cadre industriel de ce projet est de trouver une alternative à la résine phénol-formaldéhyde (RFP) et à son durcisseur, utilisée actuellement en pneumatique pour améliorer les performances aussi bien des compositions de caoutchouc que celles des produits semi-finis. Un des aspects essentiels de la pneumatique est d’augmenter la rigidité à faible déformation des pneus sans augmenter l'hystérésis des élastomères durcis chargés de noir de carbone. Ainsi, l'objectif de ce travail de thèse est de proposer un système thermodurcissable alternatif aux résines RFP actuelles. Ce nouveau système doit être riche en carbone renouvelable et doit être chimiquement modifié au moyen de procédés écologiques. La lignine a été choisie comme source de carbone renouvelable. Une étude préliminaire a souligné les potentialités d'une classe de lignines époxy pour l'application visée. Notre approche consiste en la conception de lignines modifiées par des époxy par une méthode originale évitant l'utilisation de l'épichlorhydrine suivie de son durcissement par des agents de réticulation appropriés. Des tests préliminaires avec un composé modèle de lignine ont donné la gamme des composés époxy et les conditions à tester pour la réaction avec la lignine. Les expériences avec la lignine ont alors confirmé le potentiel de l’ester diglycidylique de l’acide 4, 5-époxytetrahydrophthalique, un composé époxy contenant à la fois un groupement cycloaliphatique et deux types de groupements époxy glycidyliques, comme alternative à l'épichlorohydrine pour la préparation de lignines modifiées. Dans les conditions que nous avons définies, la réaction donne des prépolymères de type lignine-époxy sous forme de poudre avec un niveau d’époxydation de 1,2 mol/kg déterminé par spectroscopie FTIR. La série de tests effectuée sur des mélanges de caoutchouc a montré que la nouvelle lignine époxy associée à la p-xylylènediamine peut être mélangée avec succès avec le caoutchouc naturel et peut atteindre les propriétés de notre mix de référence. / The industrial framework of this project is the substitution of phenol formaldehyde resin (RFP) and its methyl donor hardener currently used for improving the performances of rubber compositions of tires or semi-finished products for tires. A critical aspect is the need for an increase of rigidity at low deformation without enhancement of the hysteresis of the cured elastomers filled with carbon black. The specific aim of this PhD work was to propose an alternative thermosetting system to the current RFP resins. This new system should be rich in renewable carbon and chemically modified by environmentally friendly processes. Lignin was chosen as the source of the renewable carbon. A preliminary study emphasized the potentialities of a class of epoxy-modified lignins for the targeted application. The main approach was the design of epoxy modified lignin to be obtained by an original method avoiding the use of epichlorohydrine and to be subsequently cured by appropriate cross-linkers. A preliminary screening with a lignin model compound gave the range of the epoxy compounds and the conditions to be tested for the reaction with lignin. Then various experiments with lignin confirmed the potential of 4, 5-epoxytetrahydrophthalic acid diglycidylester, an epoxy compound containing both one cycloaliphatic and two glycidyl type of epoxy groups, as an alternative for epichlorohydrine for the preparation of modified lignin. In the conditions we have defined, the reaction yielded epoxy lignin-based prepolymers as a powder with epoxy level as high as 1,2 mol/kg determined by FTIR spectroscopy. The series of evaluation campaigns in rubber blends showed that the new epoxy-modified lignin associated with p-xylylenediamine can be successfully mixed with natural rubber and enable to reach the properties of our reference mix.

Made available in DSpace on 2016-12-08T17:19:32Z (GMT). No. of bitstreams: 1 Parte1.pdf: 62134 bytes, checksum: 6c68c6328894fd69d24d9c1d7f47dd80 (MD5) Previous issue date: 2008-07-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this study, carboxylated single walled carbon nanotubes (SWNTc) and single walled carbon nanotubes (SWNT) were initially randomly dispersed in the hardener to understand the benefits of its process because in most cases in the literature the dispersion firstly takes place in the epoxy resin. According to the nanotube type, different materials were used to produce nanocomposites. SWNTc was used because it was expected to improve adhesion in the nanotube / matrix interface allowing a better stress tranfer. The influence of using a solvent in the dispersion process was also investigated. In addition, time and amplitude of sonification, manual and mechanical stirring were varied to reach a homogeneous level of SWNTc dispersion in the matrix. Similarly, solvent was used together with a surfactant to help improving adhesion. The produced samples were characterized by the following analysis such as infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), dilatometry, dynamic mechanical analysis (DMA), scanning electron microscopy (SEM) and mechanical testing (tensile, flexural and microhardness). The SWNTc and SWNT were evaluated by Raman spectroscopy. Regarding the nanocomposites with SWNTc, the lowest time and amplitude of sonification improve the mechanical properties. Although a better result was achieved by not using the solvent, acetone showed to be extremely important to improve the dispersion process and consequently the final mechanical properties. Microhardness increased 32% and the Young Modulus, 32%. Regarding SWNT, the use of acetone in the dispersion process helped increasing Young Modulus (23%). Although it was possible to improve some properties, the use of surfactants aiming to improve nanotubes/matrix adhesion did not achieve the same improvement levels as acetone did in the dispersion process. Both types of nanotubes showed higher dilatation comparing to the neat epoxy, the opposite behavior to that found in the literature. The use of the solvent during the fabrication process was still found necessary to achieve na efficient dispersion. SWNTc presented a superior performance regarding mechanical properties compared to SWNT, 0.25wt% of SWNTc showed a better performance than 0.50wt% of SWNT. Two simple mathematical models were used to predict the Young Modulus for the composites, and the results of this work were very close to those calculated by those models. / Neste trabalho, a dispersão randômica de nanotubos de parede simples carboxilados (NCPSc) e nanotubos de parede simples (NCPS) inicialmente no endurecedor foi utilizada de modo a entender os benefícios desse processo, pois a grande maioria dos trabalhos na literatura baseiam-se em dispersão na resina epóxi. De acordo com o tipo de nanotubo (NC), houve uma diferenciação dos materiais empregados no processo de preparação dos nanocompósitos. O uso de nanotubos funcionalizados carboxilados (NCPSc) teve como intenção, melhorar a adesão na interface nanotubo/matnz permitindo uma melhor transferência de tensão. O estudo da utilização de solvente serviu para verificar a possibilidade de atingir um processo capaz de dispersar eficientemente sem necessidade de solvente. O tempo e amplitude de sornficação, a homogeneização manual e mecânica foram empregados na tentativa de se alcançar níveis de dispersão adequados dos NCPSc na matriz. De maneira similar, o uso de nanotubos de parede simples (NCPS) esteve associado à utilização de solvente, porem, foi empregado o uso de surfactante no intuito de melhorar a adesão entre os nanotubos e a matriz polimérica. As amostras produzidas foram caracterizadas por espectroscopia no infravermelho (FTIR), calorimetria exploratória diferencial (DSC), dilatometria, analise dinâmico mecânica (DMA), microscopia eletrônica de varredura (MEV), e ensaios mecânicos (tração, flexão e microdureza). Os nanotubos foram submetidos a espectroscopia Raman para avaliação de sua estrutura Com relação aos nanocompósitos produzidos com NCPSc, o menor tempo e amplitude de sonificação proporcionou melhorias das propriedades mecânicas. Apesar de alguma melhoria ser alcançada através da não utilização do solvente, a acetona se mostrou extremamente importante para a melhoria da dispersão e conseqüentemente das propriedades mecânicas. Houve um aumento de 32% em relação à microdureza Vickers e, ainda, foi possível aumentar também em 32% o Módulo de Young nos ensaios de tração. Para os nocompósitos com NCPS, o uso da acetona contribuiu na dispersão e por conseqüência nos ensaios de tração para um aumento de 23% do módulo. Apesar de apresentar melhorias em algumas propriedades, o uso de surfactantes não se mostrou eficiente na melhoria de transferência de tensão matriz/reforço, de modo a atingir os mesmos resultados propiciados uso de acetona na dispersão. Para ambos os tipos de nanotubos, no ensaio de dilatometria as amostras obtiveram valores de dilatação superiores ao epóxi puro, contrariando o esperado pela literatura. Pode-se dizer que ainda não é possível eliminar o solvente do processo de fabricação, já que ele faz-se necessário para uma dispersão eficaz. Pode-se dizer que NCPSc de maneira geral apresentaram performance superior como reforço em comparação aos NCPS na melhoria de propriedades mecânicas, no caso deste trabalho, em que frações mássicas de NCPSc de 0,25% m/lm) propiciam melhor desempenho que 0,50% (mim) de NCPS. Utilizou-se dois modelos matemáticos para prever o módulo de Young dos materiais compósitos, e os obtidos neste trabalho podem ser considerados próximos aos previstos por este modelos.

Sjökaptensstudenter på Sjöfartshögskolan i Kalmar genomgår praktik under sammanlagt tolv månader i form av fartygsförlagd utbildning indelad i tre olika perioder under deras fyraåriga utbildning. Praktikperioderna ombord på fartyg ger studenterna möjligheten att lära sig yrket på ett praktiskt sätt, inte bara från läroboken. Ombord på fartyg används härdplaster i en stor utsträckning och som student på Sveriges två sjöfartshögskolor går man ut på fartygsförlagda praktikperioder med olika grundkunskaper inom härdplaster. Syftet med arbetet var att undersöka hur sjökaptensstudenter förhåller sig till härdplaster genom en kvalitativ metod med semistrukturerade intervjuer där sex avgångsstudenter från Sjökaptensprogrammet i Kalmar deltog. Resultatet visar att alla respondenter hanterade härdplaster under sina praktikperioder på fartyg, i form av tvåkomponentsfärger med olika utsträckningar av förståelse angående hälsorisker och PSU som ska användas för att minska hälsorisker. Studien visade också att faktorer som ålder, erfarenheter samt hur de ombordanställdas attityd kring hantering och användning av härdplaster spelar en stor roll på hur studenter förhåller sig till härdplaster. / Sea captain students at the Kalmar School of Maritime Capital undergo internship for a total of twelve months in the form of onboard education divided into three different periods during their four-year training. Practice periods onboard ships give students the opportunity to learn the profession in a practical way, not just from the textbook. Onboard ships, hardener is used extensively and as a student at Sweden’s two maritime universities goes out on onboard training with different basic knowledge about hardeners. The aim of the work was to examine how sea captain students relate to hardener through a qualitative method of semistructured interviews where six last year students from the sea captain Program in Kalmar participated. The result shows that all respondents handled hardener during their onboard training in the form of two-component paint with different extensions of understanding regarding health risks and PPE to be used to reduce its risks. The study also showed that factors such as age, experience and how the onboard attitude regarding handling and use of hardener play a big role in how students handle hardener by themselves.

Betong är ett av världens vanligaste byggmaterial och består av cement, ballast, vatten och eventuella tillsatser. Trots dess utbredda användning uppstår det ofta problem både vid gjutning och efter gjutning. För att motverka dessa problem behandlas betongen på olika sätt, bland annat genom fukthärdning vid gjutning. Fukthärdning medför att fukt hindras avgå från betongen under hydratationen. Har betongen inte tillräckligt med fukt finns det risk att hållfasthetstillväxten avstannar. Syftet med arbetet är att studera hur fukthärdning med en vattenbaserad membranhärdare med silikat påverkar uttorkning och hållfasthet för en betong med lågt vct. I arbetet jämförs fullständig fukthärdning med plast, fukthärdning med membranhärdare och betong som lufthärdas. Membranhärdaren som använts är en vattenbaserad membranhärdare med silikat och den använda betongen har ett vct på 0,38 och hållfasthetklass C45/55. Hållfasthetsutvecklingen hos betong startar så fort cement blandas med vatten och den kemiska reaktionen kallas hydratation. Vid hydratationen reagerar belit (C2S) och alit (C3S) som finns i cement med vatten och bildar bland annat kalciumsilikathydrat (C-S-H) vilket är den beståndsdel som ger betongen sin hållfasthet. Faktorerna som påverkar betongens hållfasthetsutveckling är bland annat fukttillgång, temperatur, cementtyp och vattencementtal. Direkt efter gjutning innehåller betong stora mängder fukt, både som fritt vatten och i form av vattenånga, som ska torka ut. Uttorkningen av betong tar lång tid och pågår tills den är i fuktjämvikt med omgivningen. Uttorkningshastigheten beror på olika faktorer som vct och tillsatser, även metod för fukthärdning kan påverka uttorkningstiden. För att besvara syftet har betongkuber gjutits som fukthärdats med antingen membranhärdare eller genom att plastats in, samt har vissa kuber lufthärdats. I vissa betongkuber placerades fuktmätare för mätning av relativ fuktighet. Övriga provkuber provtrycktes för bestämning av tryckhållfasthet. Resultatet visar att membranhärdaren medför en långsammare uttorkning jämfört med betong som inte fukthärdats, men kortare uttorkningstid jämfört med betong som plastats in. Gällande hållfastheten visar resultatet att de kuber som membranhärdats får högre medelhållfasthet än de kuber som inte fukthärdats, men lägre medelhållfasthet än de som plastats in. Diskussionen behandlar resultatet och felkällor som kan påverka resultatet, och andra saker som kan påverka resultatet. Hållfastheten för de kuber som inte fukthärdats påverkas av en stor avvikelse, till skillnad mot de kuber som fukthärdats. Detta medför en stor påverkan på medelhållfastheten. Slutsatsen från arbetet visar att det finns tendenser som visar på längre uttorkningstid jämfört med betong som inte fukthärdats, men betong som plastats in har längre uttorkningstid än membranhärdad med den använda membranhärdaren. Gällande hållfastheten syns inget tydligt samband mellan hållfasthet och membranhärdning och att det behövs fler provkuber som testas för ett pålitligt resultat. / Concrete is one of the most common building materials in the world, consisting of cement, aggregate, water and optional additives. Despite its widespread use, problem often arise. To counteract these issues, concrete is treated in various ways, such as moist curing after casting, as insufficient moisture during hydration can halt strength development. The aim of this study is to investigate how moist curing with a water-based membrane hardener containing silicate affects dehydration and strength for concrete with low water-tocement ratio (w/c). The study compares complete moist curing with plastic, moist curing with membrane hardener and uncured concrete. The membrane hardener used is a water- based membrane hardener with silicate, and the concrete used has a water-to-cement ratio of 0,38 and a strength class of C45/55. The development of strength in concrete begins as soon as cement is mixed with water, and this chemical reaction is called hydration. During hydration, belite (C2S) and alite (C3S) in the cement react with water and form, among other things, calcium silicate hydrate (C-S-H), which is the component that gives concrete its strength. Factors that affect the strength development of concrete include moisture availability, temperature, type of cement, and water-cement ratio. Immediately after casting, concrete contains large amounts of moisture, both as free water and in the form of water vapor, which needs to dry out. The drying of concrete takes a long time and continues until it reaches moisture equilibrium with the surrounding environment. The drying rate depends on various factors such as water-cement ratio and additives, and the method of moisture curing can also affect the drying time. To address the objective, concrete cubes were cast and cured using either a membrane curing compound or by being wrapped in plastic, while some cubes were air-cured. Moisture meters were placed in some of the concrete cubes to measure relative humidity. The remaining test cubes were subjected to compression testing to determine their compressive strength. The results indicate that the membrane hardener leads to slower drying compared to uncured concrete cubes, but shorter drying times compared to plastic sheet curing. Regarding strength, the results shows that that cubes treated with membrane hardener exhibit higher average compressive strength than uncured cubes but lower average compressive strength then the cubes moisture cured with plastic. The discussion addresses the results and potential sources of error, and other things that can affect the result. The significant deviation in strength for uncured cubes compared to those subjected to moist curing greatly impacts the average compressive strength. The conclusion suggests trends indicating longer drying times compared to uncured concrete cubes, moisture curing with plastic curing demonstrating longer drying times than membrane hardening with the specific membrane hardener used. Regarding strength, no clear correlation is observed between strength and membrane hardener, indicating the need for further testing with more specimens for reliable results.

Indiana University-Purdue University Indianapolis (IUPUI) / The purpose of this study was to evaluate the fracture resistance of three post and core systems in endodontically treated teeth by loading to failure, and to measure marginal gaps before and after cyclic loading. Sixty extracted canines were assigned to three groups. The groups tested were: 1) Single cast post and core (Group CP). 2) Prefabricated metal post and composite resin core (Group MR). 3) Glass fiber post and composite resin core (Group FR). All teeth were obturated and prepared to receive a post and core with a coping. Thirty teeth (10 from each group) were loaded to failure, and the other 30 teeth were fatigue-loaded. The marginal gaps on the facial and lingual surface of the fatigue-loaded group were measured before and after cyclic loading. There were two hypotheses for this study. The first was that the FR group would have less marginal gap opening on the lingual surface than the other groups. The second was that the CP group would have a higher load at failure than the other groups. Group CP was found to have a significantly smaller pre-loading marginal gap than group FR (p = 0.0265) and group MR (p = 0.0273), while groups FR and MR did not have a significantly different pre-loading marginal gaps (p = 0.86). Group FR had significantly less change in marginal gap than group MR (p = 0.0013). Groups CP and MR did not have significantly different changes in marginal gap (p = 0.09). Groups CP and FR did not have significantly different changes in marginal gap (p = 0.11). The three post types did not have significantly different maximum loads to failure (p= 0.49), moments of inertia at cervical area (p = 0.75), or moments of inertia at fracture site (p=0.12). There was no significant difference between groups CP, FR, and MR in the load-to-failure test. Group CP demonstrated the highest load-to-failure values; however, the highest load-to-failure mean was for group MR. All fractures observed in this study were catastrophic. Group FR demonstrated better stress distribution and caused no early fractures in the fatigue-loading group. All groups demonstrated significant marginal gap changes on the lingual surface after fatigue loading; however, group FR demonstrated <45 μm marginal gap opening. In group FR, the reduced marginal gap opening was attributed to the use of Panavia 21 with the proper surface treatments to bond to the tooth structure, the resin composite, and the metal coping.