Moisture damage in asphalt mixtures is a complex phenomenon that involves mechanical, chemical, physical and thermodynamic processes. This damage contributes significantly to the premature deterioration of asphalt pavements, which leads to extra cost in highway maintenance and vehicle operations. One key mechanism of how moisture reaches the asphalt-aggregate interface is by its permeation or diffusion through the asphalt binder or mastic. Different techniques are available for diffusion coefficient measurement of a wide variety of polymersolvent systems. For the asphalt-water system studied, the focus is on two techniques: (i) Fourier Transform Infrared (FTIR)-Attenuated Total Reflectance (ATR) spectrometry and (ii) Gravimetric Sorption Measurements. In the FTIR-ATR experiments, asphalt binders are under investigation. Water shows strong absorption in the infrared region and the FTIR-ATR technique has the ability to monitor both the kinetics of moisture ingress as well as any chemical changes occurring during the test. The changes in concentration can be directly related to change in the absorbance measured during the experiment. The hysteresis of water diffusion in asphalt binders is also monitored through this technique. In the gravimetric sorption experiments, cylindrical Fine Aggregate Mixtures (FAM) were investigated. The gravimetric techniques, which directly follow mass change with time, are among the most used techniques probably because of their simplicity. In this experiment, the Saturated Surface-Dry (SSD) weight of FAM samples at room temperature and at 100 degrees F is monitored until it reaches the equilibrium. The measurements of: (i) water uptake and (ii) the diffusion coefficient were made at both temperatures. A dual mode diffusion model was shown to better represent the diffusion of water through asphalt binders. The rate of moisture diffusion in asphalt binders was proved to be dependent on the history of exposure of the asphalt binder to the moisture. Moisture uptake and diffusivity of water through FAM is dependent on the type of aggregate and asphalt binder used to prepare the FAM.

Les biofilms sont des communautés complexes de microorganismes, enchassées dans une matrice auto-secrétée de substances polymériques extracellulaires ou EPS. Les biofilms se forment à la surface de la plupart des matériaux, qu’ils soient de nature biologique ou non, et sont à l’origine de divers problèmes économiques et sanitaires. Les bactéries dans un biofilm, dites bactéries sessiles, présentent en effet des propriétés phénotypiques qui les distinguent de leurs homologues planctoniques, notamment par une résistance accrue aux antibiotiques et aux traitements de désinfection. D’où, la nécessité de prévenir leur formation et/ ou de leur élimination à partir de stratégies mieux adaptées à ce mode de vie en communauté. Le développement de telles stratégies passe entre autre par une meilleure connaissance des contributions physico-chimiques gouvernant les interactions de ces microorganismes avec leur environnement proche notamment lors des étapes initiales de la formation des biofilms. Deux grands objectifs ont été fixés au début de cette thèse, le premier visant à caractériser, in situ et en temps réel la formation de jeunes biofilms de deux modèles bactériens : une souche naturelle et ubiquitaire de Pseudomonas fluorescens et une souche modèle d’Escherichia coli obtenue par génie génétique pour surexprimer un seul type d’EPS. Le deuxième objectif de cette thèse, consiste à étudier leurs réponses à un stress environnemental ou chimique, notamment quand les biofilms doivent se développer dans des conditions extrêmes de pH. Pour atteindre ces objectifs, différentes techniques ont été combinées pour étudier de l’échelle moléculaire à l’échelle cellulaire le développement des biofilms. La spectroscopie Infrarouge à Transformée de Fourier en mode réflexion totale atténuée (FTIR-ATR) a été utilisée pour suivre en temps réel le développement des biofilms. Nous avons pu suivre l’évolution des empreintes spectrales IR-ATR au cours de la formation des biofilms, sous des conditions favorables ou non à leur croissance. De jeunes biofilms de 24 h ont été étudiés par microspectroscopie Raman confocale (MRC), celle ci permettant d’obtenir des informations localisées sur la composition chimique des biofilms. La structure générale des biofilms a été visualisée par la microscopie à épifluorescence. Finalement, les propriétés physico-chimiques des EPS ont été quantifiées par spectroscopie de force atomique à l’échelle de la molécule unique (SMFS pour Single Molecule Force Spectroscopy). / Biofilms are complex communities of microorganisms, embedded in an auto-produced matrix of extracellular polymeric substances or EPS. Biofilms form on the surface of most materials, whether or not they are of biological nature, and cause major economic problems as well as public health concerns. Bacteria within a biofilm also called sessile bacteria, have phenotypic characteristics that distinguish them from their planktonic counterparts, rendering them more resistant to antibiotics and to disinfection strategies. Hence, the prevention of their formation and/ or their elimination requires the use of strategies that are well suited to the sessile mode of life. The development of these strategies begins with a better understanding of the physicochemical contributions that govern the interaction between the sessile community and its environment especially during the first steps of biofilm formation. Two main objectives were defined at the beginning of this thesis, the first was to characterize, in situ, and in real time the development of nascent biofilms. Two bacterial models were studied: a natural and ubiquitous strain of Pseudomonas fluorescens and a model strain of Escherichia coli genetically modified to overexpress one type of EPS. The second objectif was to study their responses towards an environmental or chemical stress; particularly how their development would be affected under extreme conditions of pH. To gain these objectives, different techniques were combined to study from the molecular to the cellular scale the development of biofilms. Fourier Transform Infrared spectroscopy in attenuated total reflection mode was used to evaluate in real time the development of biofilms. We were able to detect changes in the IR-ATR spectral profile along biofilm formation under favorable and non favorable growth conditions. 24 h - old biofilms were characterized using confocal Raman microspectroscopy, which allowed us to gather localized information on their chemical composition. The structure of biofilms was visualized using epifluorescence microscocopy. Finally, physico-chemical properties of EPS were quantified using single molecule force spectroscopy

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

O objetivo deste trabalho é estudar o nível de organização dos cristalitos de surfactantes aniônico, catiônico e zwiteriônico com o aumento na densidade destas moléculas sobre um cristal de germânio. As análises foram realizadas por espectroscopia de infravermelho com transformada de Fourier acoplada à técnica de reflexão total atenuada (FTIR-ATR). Este estudo apresenta importantes aspectos na organização do dodecilsulfato de sódio (SDS), do N-hexadecil-N,N-dimetil-3-amônio-1-propanosulfato (HPS), do brometo de hexadeciltrimetilamônio (CTAB) e do brometo de dodeciltrimetilamônio (DTAB). No SDS é observado um deslocamento de 1.7 cm-1 para valores de maior frequência na banda de estiramento assimétrico do CH2, vass (CH2), enquanto que é observado um deslocamento de 0.9 cm-1 na banda de estiramento simétrico, vsim (CH2). Este deslocamento para valores de maior frequência nas bandas de estiramento está associado com um aumento na desorganização da cadeia alifática com o aumento na densidade de moléculas sobre o elemento de ATR. A banda de deformação angular do CH2, δ(CH2), apresenta um valor em 1468 cm-1 que é também um indicativo de desorganização. No CTAB não é observado variações acentuadas nos valores das frequências vibracionais. Na banda vass (CH2) do DTAB é observado um deslocamento de 4.5 cm-1 para valores de menor frequência. Embora seja observado valores próximos de 2920 cm-1 para a banda vass (CH2), que é um indicativo do estado líquido de surfactantes, o que é observado nesse estudo são cristalitos de DTAB. O deslocamento da banda vsim (CH2) do DTAB é da ordem de 2 cm-1. Estas mudanças nas bandas vass (CH2) e vsim (CH2) são um indicativo da diminuição nas conformações gauche e um aumento nas conformações trans ao longo da cadeia alifática. O valor da freqüência em torno de 1472 cm-1 para a banda δ(CH2) é também um indicativo de uma maior organização na cadeia de CH2 do DTAB. Para o HPS é observado um deslocamento de 2.6 e 2.7 cm-1 para valores de maior frequência nas bandas vass (CH2) e vsim (CH2), respectivamente. A banda δ(CH2) do HPS apresenta um deslocamento de 4 cm-1 para valores de maior frequência. A variação nas bandas vass (CH2), vsim (CH2), e δ(CH2) ressalta o aumento na desorganização da cadeia alifática com o aumento na densidade de moléculas de HPS sobre o germânio. / The objective of this work is study the order level of anionic, cationic and zwitterionic surfactants with the increase of their density packing on the surface of a germanium element. The analyses were performed by a Fourier transform infrared-attenuated total reflection spectroscopy. This study shows important insights on the conformational order of sodium dodecyl sulfate (SDS), N-hexadecyl-N-N -dimethyl-3-ammonio-1-propane-sulfonate (HPS), hexadecyl-trimethylammonium bromide (CTAB) and dodecyl trimethylammonium bromide (DTAB). It is observed a shift of 1.7 and 0.9 cm-1 to higher frequency values of the CH2 asymmetric (vass (CH2)) and symmetric (vsim(CH2)) stretching bands for the SDS molecules, respectively. The latter shift to higher frequency values is associated with the disorder of the aliphatic chain due to the increase of density packing of SDS molecules on the germanium element. The CH2 scissoring band [δ (CH2)] shows a value in 1468 cm-1, which is also an indicative of conformational disorder. It is not observed any accentuated change on the vibrational frequency values of the CTAB molecules. The vass (CH2) band of the DTAB molecules is shifted 4.5 cm-1 to lower frequency values. Although it is observed values near 2920 cm-1 for the vass(CH2) band, indicating a surfactant liquid phase, it is shown in this study that there are indeed DTAB crystallites. The shift of DTAB vsim(CH2) band is around 2 cm-1. These changes in vass(CH2) and vsim(CH2) band are an indicative of a decrease in gauche conformations and an increase in all-trans conformations over the aliphatic chain. The frequency value around 1472 cm-1 for the δ(CH2) band is also an indicative of the order in CH2 chain of DTAB. It is observed a shift of 2.6 and 2.7 cm-1 to higher frequency values of vass (CH2) and vsim(CH2) bands of the HPS molecule, respectively. The δ(CH2) band of the HPS molecule presents a shift of 4 cm-1 to higher frequency values. These variations in vass (CH2), vsim(CH2), and δ(CH2) bands stand out the disorder of the aliphatic chain due to the increase of the density packing for the HPS molecules on the germanium surface.

Submitted by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2016-01-06T18:54:10Z No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) mayara_rodrigues_lessa.pdf: 2887620 bytes, checksum: 65d145401884724e28b09bbc9441aa53 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2016-01-07T11:52:11Z (GMT) No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) mayara_rodrigues_lessa.pdf: 2887620 bytes, checksum: 65d145401884724e28b09bbc9441aa53 (MD5) / Made available in DSpace on 2016-01-07T11:52:11Z (GMT). No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) mayara_rodrigues_lessa.pdf: 2887620 bytes, checksum: 65d145401884724e28b09bbc9441aa53 (MD5) Previous issue date: 2014 / O caf? torrado e mo?do encontrado no mercado interno ? comercializado sob diferentes marcas, que trazem consigo uma heterogeneidade quanto ao aroma, sabor e at? o grau de torra??o. Esta diversidade de caracter?sticas est? associada a v?rios fatores, entre eles a origem dos gr?os de caf?. Considerando essas varia??es relatadas na literatura, o presente trabalho teve como objetivo realizar uma pesquisa da composi??o qu?mica e f?sico-qu?mica de caf?s comerciais em diferentes cidades da Regi?o Sudeste do Brasil. Cinquenta e oito pacotes de 250 gramas, de caf?s torrados e mo?dos acondicionados em embalagem do tipo almofada e/ou ? v?cuo foram adquiridos em diferentes cidades dos quatro Estados da Regi?o Sudeste do Brasil. Todos os produtos estavam dentro do prazo de validade e aproximadamente 58% das marcas apresentavam o selo de pureza da ABIC, enquanto 22% das marcas apresentavam o selo de qualidade da Associa??o Brasileira da Ind?stria de Caf?. As amostras foram levadas para o Laborat?rio de Tecnologia de Biomassas do Cerrado da Universidade Federal dos Vales do Jequitinhonha e Mucuri, onde foram realizadas as avalia??es de pH cujo resultado m?dio foi 5,95; acidez total titul?vel 15,03 ? 1,07(v/m)%; s?lidos sol?veis totais 1,15 ?Brix; ?ndice de colora??o com m?dia para os valores de L* de 28,87 ? 0,29, para os valores de a* de 8,99 ? 0,10 e para os valores de b* de 2,84 ? 0,21; os compostos fen?licos obtiveram uma m?dia de 4,1152 ? 0,4863 g.100g-1 e a m?dia dos flavonoides de 0,5042 ? 0,0291 g.100g-1. Os m?todos multivariados de an?lise, associados aos m?todos usando a espectroscopia na regi?o do infravermelho tem tido grandes avan?os com diversas aplica??es nas an?lises de alimentos. Com este intuito, utilizou-se a espectroscopia na regi?o do infravermelho para delinear os grupos funcionais mais representativos nas amostras de caf? analisadas com a inten??o de agrup?-las por similaridade atrav?s da estat?stica multivariada. Os resultados permitiram visualizar que poucos grupos foram formados utilizando as an?lises f?sico-qu?micas, para classificar as amostras. A An?lise das Componentes Principais foi capaz de acumular 61,98% de vari?ncia nas duas primeiras componentes e os grupos formados foram confirmados pela An?lise Hier?rquica por Agrupamento. Em rela??o aos espectros de infravermelho, as amostras foram mais agrupadas com a An?lise das Componentes Principais acumulando 41,76% da vari?ncia, os grupos das amostras foram confirmados pela An?lise Hier?rquica por Agrupamento. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2014. / ABSTRACT The roast and ground coffee found in the domestic market is sold under different brands that carry with them a heterogeneity for aroma, flavor and even the degree of roasting. This diversity of characteristics is associated with several factors, including the origin of the coffee beans. Considering these variations reported in the literature, the present study aimed to perform a search of the chemical and physico-chemical composition of commercial coffees in different cities in Southeastern Brazil. Fifty-eight packages of 250 grams of roasted and ground coffee packaged in packaging the type pad and / or vacuum were acquired in different cities of the four states of southeastern Brazil. All products were within the validity period and approximately 58% of brands had the seal of purity of ABIC, while 22% of brands had the seal of the Brazilian Association of Coffee Industry Samples were taken for Laboratory Technology Biomass of the Cerrado, Federal University of the Jequitinhonha and Mucuri, which were conducted evaluations of pH where the average yield around 5.95; titratable acidity 15.03 ? 1.07 (v / m)%; total soluble solids 1.15 ? Brix; staining index and the average for the values ??of L * was 28.87 ? 0.29 for the a * values ??was 8.99 ? 0.10 and b * values ??were 2.84 ? 0.21 ; phenolic compounds were obtained an average of 4.1152 ? 0.4863 g.100g-1 and the average of flavonoids was 0.5042 ? 0.0291 g.100g-1. The multivariate analysis methods, associated with methods using spectroscopy in the infrared region has taken great strides with several applications in food analysis. For this purpose, we used spectroscopy in the infrared region to delineate the most representative functional groups in coffee samples analyzed with the intention of grouping them by similarity using multivariate statistics. The results allowed us to visualize that few groups were formed using the physicochemical analyzes to classify the samples. The Principal Component Analysis was able to accumulate 61.98% of variance in the first two components and the groups formed were confirmed by Hierarchical Cluster Analysis. Regarding the infrared spectra of the samples were further grouped with the Principal Component Analysis accumulating 41.76% of the variance, the groups of samples were confirmed by Hierarchical Cluster Analysis.

O objetivo deste trabalho é estudar o nível de organização dos cristalitos de surfactantes aniônico, catiônico e zwiteriônico com o aumento na densidade destas moléculas sobre um cristal de germânio. As análises foram realizadas por espectroscopia de infravermelho com transformada de Fourier acoplada à técnica de reflexão total atenuada (FTIR-ATR). Este estudo apresenta importantes aspectos na organização do dodecilsulfato de sódio (SDS), do N-hexadecil-N,N-dimetil-3-amônio-1-propanosulfato (HPS), do brometo de hexadeciltrimetilamônio (CTAB) e do brometo de dodeciltrimetilamônio (DTAB). No SDS é observado um deslocamento de 1.7 cm-1 para valores de maior frequência na banda de estiramento assimétrico do CH2, vass (CH2), enquanto que é observado um deslocamento de 0.9 cm-1 na banda de estiramento simétrico, vsim (CH2). Este deslocamento para valores de maior frequência nas bandas de estiramento está associado com um aumento na desorganização da cadeia alifática com o aumento na densidade de moléculas sobre o elemento de ATR. A banda de deformação angular do CH2, δ(CH2), apresenta um valor em 1468 cm-1 que é também um indicativo de desorganização. No CTAB não é observado variações acentuadas nos valores das frequências vibracionais. Na banda vass (CH2) do DTAB é observado um deslocamento de 4.5 cm-1 para valores de menor frequência. Embora seja observado valores próximos de 2920 cm-1 para a banda vass (CH2), que é um indicativo do estado líquido de surfactantes, o que é observado nesse estudo são cristalitos de DTAB. O deslocamento da banda vsim (CH2) do DTAB é da ordem de 2 cm-1. Estas mudanças nas bandas vass (CH2) e vsim (CH2) são um indicativo da diminuição nas conformações gauche e um aumento nas conformações trans ao longo da cadeia alifática. O valor da freqüência em torno de 1472 cm-1 para a banda δ(CH2) é também um indicativo de uma maior organização na cadeia de CH2 do DTAB. Para o HPS é observado um deslocamento de 2.6 e 2.7 cm-1 para valores de maior frequência nas bandas vass (CH2) e vsim (CH2), respectivamente. A banda δ(CH2) do HPS apresenta um deslocamento de 4 cm-1 para valores de maior frequência. A variação nas bandas vass (CH2), vsim (CH2), e δ(CH2) ressalta o aumento na desorganização da cadeia alifática com o aumento na densidade de moléculas de HPS sobre o germânio. / The objective of this work is study the order level of anionic, cationic and zwitterionic surfactants with the increase of their density packing on the surface of a germanium element. The analyses were performed by a Fourier transform infrared-attenuated total reflection spectroscopy. This study shows important insights on the conformational order of sodium dodecyl sulfate (SDS), N-hexadecyl-N-N -dimethyl-3-ammonio-1-propane-sulfonate (HPS), hexadecyl-trimethylammonium bromide (CTAB) and dodecyl trimethylammonium bromide (DTAB). It is observed a shift of 1.7 and 0.9 cm-1 to higher frequency values of the CH2 asymmetric (vass (CH2)) and symmetric (vsim(CH2)) stretching bands for the SDS molecules, respectively. The latter shift to higher frequency values is associated with the disorder of the aliphatic chain due to the increase of density packing of SDS molecules on the germanium element. The CH2 scissoring band [δ (CH2)] shows a value in 1468 cm-1, which is also an indicative of conformational disorder. It is not observed any accentuated change on the vibrational frequency values of the CTAB molecules. The vass (CH2) band of the DTAB molecules is shifted 4.5 cm-1 to lower frequency values. Although it is observed values near 2920 cm-1 for the vass(CH2) band, indicating a surfactant liquid phase, it is shown in this study that there are indeed DTAB crystallites. The shift of DTAB vsim(CH2) band is around 2 cm-1. These changes in vass(CH2) and vsim(CH2) band are an indicative of a decrease in gauche conformations and an increase in all-trans conformations over the aliphatic chain. The frequency value around 1472 cm-1 for the δ(CH2) band is also an indicative of the order in CH2 chain of DTAB. It is observed a shift of 2.6 and 2.7 cm-1 to higher frequency values of vass (CH2) and vsim(CH2) bands of the HPS molecule, respectively. The δ(CH2) band of the HPS molecule presents a shift of 4 cm-1 to higher frequency values. These variations in vass (CH2), vsim(CH2), and δ(CH2) bands stand out the disorder of the aliphatic chain due to the increase of the density packing for the HPS molecules on the germanium surface.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Clavulanic acid (AC) and amoxicillin (AMO) drugs are used in association and they are commercialized in Brazil as antibiotic agent. The simultaneous determination of these drugs is, usually, carried out by high performance liquid chromatography (HPLC). In the present study a methodology for simultaneous determination of AC and AMO was developed using Fourier transform mid infrared technique coupled with attenuated total reflectance (FTIR/ATR) and diffuse reflectance (DRIFTS). Nineteen commercial samples and 17 synthetic samples (28 samples for calibration set and 8 samples for prevision set) were used. Calibration models were developed using partial least squares (PLS) and interval partial least squares (iPLS), synergy partial least squares (siPLS) and backward interval partial least squares (biPLS) were used as variable selection methods. Multiplicative scatter correction (MSC) and the data centered in the media produced the best models. A relative standard error of prediction (RSEP) of 3.58% (root mean square error of prediction RMSEP = 6.17 mg g-1) for AC and RSEP of 5.12% (RMSEP = 33.58 mg g-1) for AMO was obtained after interval selection using biPLS algorithm for FTIR/ATR. For DRIFTS 4.98% (RMSEP = 8.44 mg g-1) and 4.75% (RMSEP = 23.31 mg g-1) RSEP values were obtained for AC and AMO, respectively, after selection of better intervals by siPLS. Results obtained by the proposed methodology were compared with those using the methodology by HPLC and no significant differences were obtained. Therefore, results using FTIR/ATR and DRIFTS techniques combined to multivariate analysis methods were suitable for the simultaneous determination of AC and AMO in commercial pharmaceuticals products. / Os fármacos ácido clavulânico (AC) e amoxicilina (AMO) são utilizados em associação e são comercializados no Brasil como agentes antibióticos. A determinação simultânea destes fármacos é, normalmente, realizada por cromatografia a líquido de alta eficiência (HPLC, do inglês high performance liquid chromatography). O presente estudo teve por objetivo a determinação simultânea de AC e AMO utilizando técnicas de espectroscopia de reflexão no infravermelho médio (FTIR/ATR e DRIFTS) combinadas com métodos de análise multivariada. Utilizaramse 19 amostras comerciais e 17 amostras sintéticas (28 amostras para o conjunto de calibração e 8 amostras para o conjunto previsão). Obtiveram-se modelos de calibração por mínimos quadrados parciais (PLS) e seleção de variáveis através dos algoritmos por mínimos quadrados parciais por intervalo (iPLS), por sinergismo (siPLS) e por exclusão (biPLS). Os melhores modelos foram obtidos através da utilização do pré-processamento centrado na média e do tratamento de correção do espalhamento de luz (MSC). Utilizando os dados obtidos por FTIR/ATR o modelo que apresentou melhor capacidade preditiva foi aquele que utilizou o algoritmo biPLS, fornecendo um erro padrão de predição relativo (RSEP) de 3,58% (raiz quadrada do erro médio de previsão - RMSEP = 6,17 mg g-1) para AC e RSEP de 5,12% (RMSEP = 33,58 mg g-1) para AMO. Quando utilizados os dados obtidos por DRIFTS, os melhores modelos foram os que utilizaram o algoritmo siPLS, produzindo RSEP de 4,98% (RMSEP = 8,44 mg g-1) para AC e RSEP de 4,75% (RMSEP = 23,31 mg g-1) para AMO. Os resultados de ambas as metodologias propostas foram comparados com os valores obtidos pela metodologia de referência por HPLC, não se verificando diferença significativa entre seus valores. Desta forma, os resultados mostraram que as técnicas de FTIR/ATR e DRIFTS associadas aos métodos de regressão multivariados permitiram a obtenção de modelos apropriados para a determinação simultânea de AC e AMO em formulações farmacêuticas.

Mechanical properties of (woven carbon fiber / vinyl ester matrix) composites can be greatly improved if the interphase between the reinforcing high-strength low-weight fiber and the thermoset resin is made more compliant. In order to improve the adhesion of the vinyl ester matrix to the carbon fiber, a thermoplastic coating such as poly(vinyl pyrrolidone) (PVP) can be used as an intermediate between the matrix and the fiber. The extent of mutual diffusion at the (sizing material / polymer matrix) interphase plays a critical role in determining the mechanical properties of the composite. In this research, the molecular interdiffusion across a poly(vinyl pyrrolidone))/vinyl ester monomer (PVP/VE) interface is being investigated by Fourier Transform Infrared Attenuated Total Reflectance (FTIR-ATR) spectroscopy. The ATR method which can be used to characterize the transport phenomena, offers several advantages, such as the ability to monitor the diffusion <I>in situ</I> or to observe chemical reactions. In order to separate the effects of the vinyl ester monomer diffusion and the crosslinking reaction, ATR experiments were carried out at temperatures below the normal curing temperature. Diffusion coefficients were determined by following variations in infrared bands as a function of time, and fitting this data to a Fickian model. The values of the diffusion coefficients calculated were consistent with values found in the literature for diffusion of small molecules in polymers. The dependence of diffusion coefficients on temperature followed the Arrhenius equation. Hydrogen bonding interactions were also characterized. The diffusion model used in this study, however, does not seem to be appropriate for the particular (PVP/VE) system. Because the glass transition temperature of the PVP changed as diffusion proceeded, one would expect that the mutual diffusion coefficient did not stay constant. In fact, it was shown that the Tg can drop by 140oC during the diffusion process. A more suitable model of the (PVP/VE) system should take into account plasticization, hydrogen bonding, and especially a concentration dependent diffusion coefficient. Further analysis is therefore needed. / Master of Science

FTIR-ATR och SEM användes för att analysera olika typer av ytbehandlingar då de utsatts för accelererad åldring. Ytbehandlingarna som analyserats var olika typer av akrylatemulsioner, en UV-härdande produkt, en syrahärdande produkt och en vattenburen UV-härdande produkt. Två olika metoder för att kvantifiera degraderingen av färgfilmerna undersöktes, POI-metoden och karbonylindex. Båda dessa metoder går ut på att jämföra antingen arean eller höjden av två FTIR toppar med varandra. Studien avslutades med en topografisk analys av proverna mha SEM. FTIR-ATR visade sig vara ett effektivt instrument för att undersöka degraderingen av färgfilmer. POI-metoden användes för att kvantifiera 9 av 12 ytbehandlingar och ranka Serwin Williams produkter från bäst till sämst utomhusbeständighet. De ytbehandlingar som uppvisade störst kemiska förändringar hade alla aromat komponenter. Dessa absorberar UV-ljus och påverkas därför extra mycket av fotooxidation. De ytbehandlingar som avvek från de resterande var klarlacker och den vattenburna UV-härdande färgen. Klarlackerna visade minimala kemiska förändringar och den UV-härdande produkten minskade i POI, olikt resterande ytbehandlingar. Karbonylindex visade sig inte vara en effektiv metod för att bedöma degradering av färgfilmerna då värdet ökade för två av produkterna som testades och minskade för de två andra. Karbonyltoppen vid 1720cm-1 kan dock analyseras utan att beräkna karbonylindex då den kan ge mycket intressant information om den förändrande karbonylkompositionen. Testerna av topografin med SEM visade mycket detaljerade bilder av degradering processen som föll i linje med resultaten från FTIR analysen. / FTIR-ATR and SEM were used to analyze different types of coatings exposed to accelerated ageing. The coatings valuated in this study were different types waterborne acrylic emulsions, a UV-curing coating, an acid curing coating and a waterborne UV-curing coating. Two different ways to quantify the degradation with FTIR-ATR were explored, the POI method and carbonyl index. Both methods are based on comparing the height/area of specific FTIR peaks with one another. The study was concluded with a topographic analysis with SEM for some of the samples. Results from this study shows that FTIR-ATR is an effective tool to explore the degradation of different types of coatings. The POI method was successfully used to quantify the degradation concerning 9 of the 12 studied coatings and ranking the coatings from best to worst. Coatings with aromatic components mounted the biggest chemical changes thanks to their instability when exposed to UV-radiation. Coatings that deviated from the rest were acrylic clearcoats and the waterborne UV-curing coating. Clearcoats mounted minimal chemical changes in the FTIR-ATR, and the waterborne UV-curing coating was degraded in a way that it’s POI value decreased during ageing, unlike all other coatings tested. Carbonyl index proved insufficient for quantifying degradation in this study, although the carbonyl peak around 1720 cm-1 can be analyzed manually to attain valuable information about the changing carbonyl composition. Topographical analysis with SEM gave valuable information showing detailed pictures of the degradation which all were in line with the results from the FTIR spectrums.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-01-16T16:23:02Z No. of bitstreams: 1 RafaelaMariaRibeiroBezerra_DISSERT.pdf: 4712960 bytes, checksum: bd34e8939664916c328fed12e450c278 (MD5) / Approved for entry into archive by Elisangela Moura (lilaalves@gmail.com) on 2017-01-16T16:26:52Z (GMT) No. of bitstreams: 1 RafaelaMariaRibeiroBezerra_DISSERT.pdf: 4712960 bytes, checksum: bd34e8939664916c328fed12e450c278 (MD5) / Made available in DSpace on 2017-01-16T16:26:52Z (GMT). No. of bitstreams: 1 RafaelaMariaRibeiroBezerra_DISSERT.pdf: 4712960 bytes, checksum: bd34e8939664916c328fed12e450c278 (MD5) Previous issue date: 2014-12-16 / Funda??o de Amparo ? Pesquisa do Rio Grande do Norte (Fapern) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / O objetivo do presente trabalho foi estimar os teores de carbono fixo, mat?rias vol?teis e cinzas no carv?o vegetal usando a reflect?ncia total atenuada com transformar de Fourier no infravermelho (FTIR-ATR), juntamente com os m?todos de calibra??o multivariada. V?rias t?cnicas de calibra??o multivariada, incluindo m?nimos quadrados parciais (PLS), intervalo de m?nimos quadrados parciais (IPLS), algoritmo gen?tico (GA), foram comparados e validados atrav?s do estabelecimento de teste de signific?ncia (teste t e teste de Shapiro-Wilk). Amostras de carv?o (n = 72) foram divididos em calibra??o (n = 52) e conjuntos de valida??o (n = 20), aplicando o algoritmo de sele??o cl?ssico Kennard-Stone (KS) para os espectros ATR-FTIR. Para teor de carbono fixo, o resultado obtido utilizando PLS-GA para o erro quadr?tico m?dio de valida??o cruzada (RMSECV) e previs?o (RMSEP) foram 3,77% e 4,29%, respectivamente. Para a mat?ria vol?til, RMSECV e RMSEP de 4,36% e 4,65% foi alcan?ada pelo modelo PLS utilizando sete vari?veis latentes (LV). Finalmente, para cinzas, RMSECV e RMSEP de 0,58% e 0,38%, foi alcan?ado pelo modelo PLS utilizando oito vari?veis latentes (LV). Foram realizados teste t e Quantil-quantil (Q-Q) plot para comparar os resultados dos modelos de uns com os outros e com um m?todo de refer?ncia. Estes resultados sugerem que a espectroscopia FTIR-ATR e calibra??o multivariada pode ser efetivamente usado para determinar os teores de carbono fixo, mat?ria vol?til e cinzas em carv?o vegetal brasileiro. / O objetivo do presente trabalho foi estimar os teores de carbono fixo, mat?rias vol?teis e cinzas no carv?o vegetal usando a reflect?ncia total atenuada com transformar de Fourier no infravermelho (FTIR-ATR), juntamente com os m?todos de calibra??o multivariada. V?rias t?cnicas de calibra??o multivariada, incluindo m?nimos quadrados parciais (PLS), intervalo de m?nimos quadrados parciais (IPLS), algoritmo gen?tico (GA), foram comparados e validados atrav?s do estabelecimento de teste de signific?ncia (teste t e teste de Shapiro-Wilk). Amostras de carv?o (n = 72) foram divididos em calibra??o (n = 52) e conjuntos de valida??o (n = 20), aplicando o algoritmo de sele??o cl?ssico Kennard-Stone (KS) para os espectros ATR-FTIR. Para teor de carbono fixo, o resultado obtido utilizando PLS-GA para o erro quadr?tico m?dio de valida??o cruzada (RMSECV) e previs?o (RMSEP) foram 3,77% e 4,29%, respectivamente. Para a mat?ria vol?til, RMSECV e RMSEP de 4,36% e 4,65% foi alcan?ada pelo modelo PLS utilizando sete vari?veis latentes (LV). Finalmente, para cinzas, RMSECV e RMSEP de 0,58% e 0,38%, foi alcan?ado pelo modelo PLS utilizando oito vari?veis latentes (LV). Foram realizados teste t e Quantil-quantil (Q-Q) plot para comparar os resultados dos modelos de uns com os outros e com um m?todo de refer?ncia. Estes resultados sugerem que a espectroscopia FTIR-ATR e calibra??o multivariada pode ser efetivamente usado para determinar os teores de carbono fixo, mat?ria vol?til e cinzas em carv?o vegetal brasileiro.