One of the most important and interesting unsolved problems of science is the nature of glassy dynamics and the glass transition. It is quite an old problem, and starting from the early20th century there have been many efforts towards a sound understanding of the phenomenon. As a result, there are a number of theories in the field, which do not entirely contradict each other, but between which the connection is not entirely clear. In the last couple of decades or so, there has been significant progress and currently we do understand many facets of the problem. But a unified theoretical framework for the varied phenomena associated with glassiness is still lacking. Mode-coupling theory, an extreaordinarily popular approach, came from Götze and co-workers in the early eighties. The theory was originally developed to describe the two¬ step decay of the time-dependent correlation functions in a glassy fluid observed near the glass transition temperature(Tg). The theory went beyond that and made a number of quantitative predictions that can be tested in experiments and simulations. However, one of the drawback of the theory is its prediction of a strong ergodic to non-ergodic transition at a temperature TMCT; no such transition exists in real systems at the temperatures at which MCT predicts it. Consequently, the predictions of the theory like the power-law divergences of the transport quantities (e.g., viscosity and relaxation time) fail at low enough temperature and the theory can not be used below TMCT. It is well understood now that MCT is some sort of a mean-field theory of the real phenomenon, and in real systems the transition predicted by MCT is at best avoided due to finite dimensions and activated processes, neither of which is taken into account in standard MCT. Despite its draw backs, even the most severe critic of the theory will be impressed by its power and the predictions in a regime where it works. Even though the non-ergodic transition predicted by the theory is averted, the MCT mechanism for the increase of viscosity and relaxation time is actually at work in real systems. The status of MCT for glass transition is ,perhaps, similar to the Curie-Weiss theory of magnetic phase transition and it will require hard work and perhaps a conceptual breakthrough to go beyond this mean-field picture. Discussion of such a theoretical framework and its possible directions are, however, beyond the scope of this thesis. In the first part of this work, we have extended the mode coupling theory to three important physical situations: the properties of fluids under strong confinement, a sheared fluid and for the growth kinetics of glassy domains. In the second part, we have studied a different class of non equilibrium phenomenon in arrested systems, the fluctuation relations for yielding. In the first chapter, we talk about some general phenomenology of the glass transition problem and a few important concepts in the field. Then we briefly discuss the physical problems to be addressed in detail later on in the thesis followed by a brief account of some of the important existing theories in the field. This list is by no means exhaustive but is intended to give a general idea of the theoretical status of the problem. We conclude this chapter with a detailed derivation of MCT and its successes and failures. This derivation is supposed to serve as a reference for the details of the calculations in later chapters. The second chapter deals with a simple theory of an important problem of lubrication and dynamics of fluid at nanoscopic scales. When a fluid is confined between two smooth surfaces down to a few molecular layers and an normal force is applied on the upper surface, it is found that one layer of fluid gets squeezed out of the geometry at a time. The theory to explain this phenomenon came from Persson and Tosatti. However, due to a mathematical error, the in-plane viscosity term played no role in the original calculation. We re-do this calculation and show that the theory is actually more powerful than was suggested originally by its proponents. In the third chapter, we work out a detailed theory for the dynamics of fluid under strong planar confinement. This theory is based on mode-coupling theory. The walls in our theory enter in terms of an external potential that impose a static inhomogeneous background density. The interaction of the density fluctuation with this static background density makes the fluid sluggish. The theory explains how the fluid under strong confinement can undergo a glassy transition at a higher temperature or lower density than the corresponding bulk fluid as has been found in experiments and simulations. One of the interesting findings of the theory is the three-step relaxation that has also been found in a variety of other cases. The fourth chapter consists of a mode-coupling calculation of a sheared fluid through the microscopic approach first suggested by Zaccarelli et al[J. Phys.: Condens. Matter 14,2413(2002)]. The various assumptions of the theory are quite clear in this approach. The main aim of this calculation is to understand how FDR enters with in the theory. The only new result is the modified form of Yvon-Born-Green(YBG) equations for a sheared fluid. Then we extend the theory for the case of a confined fluid under steady shear and show that a confined fluid will show shear thinning at a much lower shear rate than the bulk fluid. When a system is quenched past a phase transition point, phase ordering kinetics begins. The properties of the system show “aging” with time, and the characteristic length scale of the quenched system grows as one waits. The analogous question for glasses has also been asked in the contexts of various numerical and experimental works. We formulate a theory in chapter five for rationalizing these findings. We find that MCT, surprisingly, offers an answer to this key question in glass forming liquids. The challenge of this theory is that care must be taken in using some equilibrium relations like the fluctuation-dissipation relation(FDR), which is one of the key steps in most of the derivations of MCT. We find that the qualitative, and some times even the quantitative, picture is in agreement with numerical findings. A similar calculation for the spin-glass case also predicts increase of the correlation volume with the waiting time, but with a smaller exponent than the structural glass case. We extended this theory to the case of shear and find that shear cuts off the growth of the length-scale of glassy correlations when the waiting time becomes of the order of the inverse shear rate. For the case of sheared fluid, if we take the limit of the infinite waiting time, the system will reach a steady state. Then, the resulting theory will describe a fluid in sheared steady state. The advantage of this theory over the existing mode-coupling theories for a sheared fluid is that FDR has not been used in any stage. This is an important development since the sheared steady state is driven away from equilibrium. Interestingly, the theory captures a suitably-defined effective temperature and gives results that are consistent with numerical experiments of steady state fluids(both glass and granular materials). We give the details of a theoretical model for jamming and large deviations in micellar gel in the sixth chapter. This theory is motivated by experiments. Through the main ingredient of the attachment-detachment kinetics and some simple rules for the dynamics, the theory is capable of capturing all the experimental findings. The novel prediction of this work is that in a certain parameter range, the fluctuation relations may be violated although the large deviation function exists. We argue that a wider class of physical systems can be understood in terms of the present theory. In the final chapter, we summarize the problems studied in this thesis and point out some future directions.

The thesis describes the study of structure and dynamics of polymers in confined geometry. We study the finite size effect on the dynamics of non glassy and glassy polymers. Systematic measurement have been performed to address the issue of the possibility of entanglement and hence reptation dynamics of the polymer segments in confinement. The confinement effect on the glassy dynamics has been studied for Langmuir monolayers as well as for polymer nanoparticle hybrid systems. Slow and heterogeneous dynamics are the underlined observed behavior for dynamics in hybrid systems. The available theories explains the slowing down of the dynamics as the system is cooled from the liquid state in terms of increasing cooperative motion of the molecules. The size of the cooperative region is predicted to grow with reducing temperature. Experiments, theories and simulation in confined dimensions have been motivated to detect this length scale of the cooperatively rearranging region. The surface and interface effects on glass transition were studied using measurements based on modulated differential scanning calorimetry and small angle X ray scattering techniques. The dynamical heterogeneity in glassy polymers were studied using advanced X ray photon correlation spectroscopy techniques. Our studies presented in this thesis are also an small step to contribute to the existing experimental results on studying the surface, interface and finite size effects on the morphology and dynamics of confined systems. These effects were studied for, firstly ultra thin Langmuir monolayers and secondly polymer nanoparticle hybrid systems. In Chapter 1, we provide the theoretical background along with brief review of the literature for understanding the results presented in this thesis. The details of the experimental set up and their operating principle along with the details of the experimental conditions are provided in Chapter 2. In Chapter 3 we presents our experimental results on surface morphology and surface dynamics in ultra thin Langmuir monolayer of polymers. Chapter 4 and Chapter 5 discusses the result based on polymer nanoparticle hybrid systems. We provide the summary of our result and the future prospective of the work in Chapter 6. In appendix we have shown the complete derivation of the equation used in Chapter 3 for understanding the surface morphology of Langmuir monoalyers on water surface. Chapter 1 provides in detail the introduction to several aspects related with the dynamics of both glassy and non glassy polymers in confinement. It starts with brief introduction to structure and dynamics of polymers in bulk. In the next section we discuss the macroscopic viscoelastic behavior of materials followed by a very brief discussion on the common techniques used for such measurement. Further it discusses the theory and several available models present in literature to understand the dynamics of glass transition. This section is followed by discussion on surface and interface effects on structure and dynamics of such systems in confinement. Towards the end of this chapter we discuss the universal behavior of slow dynamic observed in soft glassy materials. Chapter 2 contains the details of the experimental techniques which has been used for the study. Brief introduction to basic principles of the measurements followed by details of the material and methods have been provided. The surface morphology and dynamics of Langmuir monolayer of polymers confined at air water interface, under compressive mechanical strain has been discussed in Chapter 3. The results presented for surface morphology are based on the studies using the combination of in situ grazing angle incidence small angle X ray scattering and ex situ atomic force microscopy measurements on monolayers transfered on silicon substrate. The issue of the presence of reptation motion in confinement has been addressed by performing systematic measurements as a function of surface concentration and molecular weight at fixed temperature. The glassy dynamical behavior has been studied on different glassy polymer layer as a function of surface concentration and temperature. In Chapter 4 we show the glass transition behavior of polymer nanoparticle (PMMA gold) hybrid system based on thermal measurements. This chapter discusses the role of the existence of a length scale in deciding the dynamics of the glass transition temperature of polymers. The confinement effect was tuned by the variation of the inter particle spacing between the nanoparticles in the polymer matrix. It also discusses the model to understand the observed behavior of the glass transition temperature in terms of the tunability of the polymer particle interface and the effect of the interface morphology on the dynamics of glass transition temperature. Chapter 5 is about the study of dynamics of polymer nanocomposites near glass transition as a function of temperature, wave vector and volume fraction of gold nanoparticles using X ray photon correlation spectroscopy. Based on our experimental results , we provide a phase diagram for dynamics in 2D space of temperature, wave vector and volume fraction for our PMMA gold nanoparticle hybrid samples. Chapter 6 contains the summary and the future perspective of the work presented.

This study aims to validate and develop applications for a novel impedance-based process analytical technology for monitoring the attributes of the product during the entire freeze-drying process (from pre-freezing and annealing to primary and then secondary drying). This measurement approach involves the application of foil electrodes, mounted externally to a conventional glass freeze-drying vial, and coupled to a high-impedance analyser. The location of the electrodes on the outside, rather than the inside of the vial, leads to a description of the technology as a through-vial impedance spectroscopy (TV-IS) technique. The principle observation from this approach is the interfacial-polarization process arising from the composite impedance of the glass wall and product interface. For a conventional glass vial (of wall thickness ~ 1 mm and cross sectional diameter ~ 22 mm) it was shown that the process is manifest within the frequency range 101 to 106 Hz, as a single, broad band peak which spans 2-3 decades of the imaginary part spectrum. Features of the interfacial-relaxation process, characterised by the peak amplitude, C″Peak, and peak frequency, fpeak, of the imaginary capacitance spectra and the equivalent circuit elements that model the impedance spectra (i.e. the solution resistance (R) and solution capacitance (C) were monitored along with the product temperature data during the cycle(s), for a variety of surrogate formulations comprising lactose, sucrose, mannitol or maltodextrin solutions, during the freezing, re-heating, annealing and primary drying stages of freeze drying). It was shown that the parameters, fpeak and R, are strongly coupled to each other and change as a function of the temperature of the solution and its phase state, whereas C″Peak is strongly coupled to the amount of ice that remains during the drying process. Both log fpeak and log R have a linear dependence on the temperature of the solution, provided there was no phase change in the solution. The crystallization process (ice onset, solidification and equilibration to shelf temperature) is characterized well by both log fpeak and log R, whereas the parameter R demonstrates most clearly the formation of eutectic crystallization during freezing. In contrast it was the parameter C which was most sensitive to the detection of the glass transition during re-heating. During primary drying, it was shown that C″peak, is dependent on the amount of ice remaining and therefore provides a convenient assessment of the rate of drying and primary drying end point. The impedance changes during annealing provide a mechanistic basis for the modifications in ice structure which result directly in the observed decrease in primary drying times. The principal observation on annealing of a 10% w/v solution of maltodextrin, was the minimal changes in the glass transition (recorded at ~−16 °C) during the re-heating and cooling step (post-annealing). This result alone appears to indicate that a maximum freeze concentration was achieved during first freezing with no further ice being formed on annealing. The phenomenon of devitrification (and the production of more ice, and hence larger ice crystals) was therefore discounted as the mechanism by which annealing impacts the drying time. Having excluded devitrification from the mechanism of annealing enhanced drying, it was then possible to conclude that the decrease in the electrical resistance (that was observed during the annealing hold time) must necessarily result from the simplified structure of the unfrozen fraction and the improved connectivity of ice crystals that may be the consequence of Ostwald ripening. The application of through vial impedance measurement approach provides a non-invasive, real time monitoring of critical process parameters which subsequently leads to an improved understanding of the mechanisms and effects of different parameters, providing a reliable basis for process optimization, along with improved risk management to ensure optimum quality of the formulation and optimization of the freeze drying process.

The dynamic relaxation characteristics of Matrimid® (BTDA-DAPI) polyimide and several functionalized aromatic polyimides have been investigated using dynamic mechanical and dielectric methods. The functionalized polyimides were thermally rearranged to generate polybenzoxazole membranes with controlled free volume characteristics. All polyimides have application in membrane separations and exhibit three motional processes with increasing temperature: two sub-glass relaxations (ƴ and β transitions), and the glass-rubber (α) transition. For Matrimid, the low-temperature ƴ transition is purely non-cooperative, while the β sub-glass transition shows a more cooperative character as assessed via the Starkweather method. For the thermally rearranged polyimides, the ƴ transition is a function of the polymer synthesis method, thermal history, and ambient moisture. The β relaxation shows a dual character with increasing thermal rearrangement, the emerging lower-temperature component reflecting motions encompassing a more compact backbone contour. For the glass-rubber (α) transition, dynamic mechanical studies reveal a strong shift in Tα to higher temperatures and a progressive reduction in relaxation intensity with increasing degree of thermal rearrangement. The dynamic relaxation characteristics of poly(ether imide) and poly(methyl methacrylate) nanocomposites were investigated by dynamic mechanical analysis and dielectric spectroscopy. The nanoparticles used were native and surface-modified fumed silicas. The nanocomposites display a dual glass transition behavior encompassing a bulk polymer glass transition, and a second, higher-temperature transition reflecting relaxation of polymer chain segments constrained owing to their proximity to the particle surface. The position and intensity of the higher-temperature transition varies with particle loading and surface chemistry, and reflects the relative populations of segments constrained or immobilized at the particle-polymer interface. Dielectric measurements, which were used to probe the time-temperature response across the local sub-glass relaxations, indicate no variation in relaxation characteristics with particle loading. Nanocomposite studies were also conducted on rubbery poly(ethylene oxide) networks crosslinked in the presence of MgO or SiO2 nanoparticles. The inclusion of nanoparticles led to a systematic increase in rubbery modulus and a modest positive offset in the measured glass transition temperature (Tα) for both systems. The sizeable increases in gas transport with particle loading reported for certain other rubbery nanocomposite systems were not realized in these crosslinked networks.

L'alternance de deux groupes de polarités très différentes, CH2 et CF2, permet au poly fluorure de vinylidène (PVDF) d’être un polymère industriellement très intéressant. Cependant, cette spécificité mène aussi à d’importantes inversions du monomère lors de la polymérisation vinylique. Pendant la polymérisation, en complément de la propagation tête-queue, CH2CF2CH2CF2, les monomères inversés conduisent à l’addition en queue-queue, CF2CH2CH2CF2, et tête-tête, CH2CF2CF2CH2. Le taux de transformation de polymère se trouve expérimentalement entre 3 et 7%. Ce pourcentage élevé entraine sans aucun doute la modification de propriétés macroscopiques. En utilisant la dynamique moléculaire, cette thèse a pour but de montrer l'effet de ces défauts sur la température de transition vitreuse (Tg), la dynamique locale et sur la température de fusion (Tm) du PVDF. En phase amorphe, le PVDF avec différents pourcentages de régio-défauts a été étudié : 3.6, 4.1, 9.3 et 23%. Cette étude permet de prédire le comportement de polymères qui ne sont pas synthétisés. Étant donné que les Tg simulées et expérimentales concordent avec précision, les motifs moléculaires qui donnent lieu à l'effet plastifiant de l'inversion de monomères peuvent être envisagés. En plus d'accentuer leur effet de plastifiant, la conclusion significative est que la relaxation de la chaîne peut être révélée en abordant explicitement des mouvements locaux. Car cette procédure ne peut pas être déduite de la connaissance du Tg, nous avons basé notre analyse sur le fait cela : 1) Nous avons démontré que des relations linéaires directes entre Tg et l'énergie d'activation conformationnelle de transition (Ea) extraite à partir d'un graphe d'Arrhenius, existent. Ce diagramme correspond au logarithme naturel des taux de transition entre les états rotameriques contre l'inverse de la température. La pente de cette courbe rapporte directement à cet Ea efficace. Un tel lien a été seulement spéculé dans la littérature. 2) Nous avons calculé des relations d'Arrhenius pour différents genres de torsions le long de la chaîne d'épine dorsale. En conséquence, une barrière d'énergie potentielle, ea, est associée à la rotation d'un lien dans un environnement spécifique. L'addition de ces énergies pesées par le pourcentage de chaque lien le long de l'épine dorsale, donne un ea moyen qui est équivalent à l'ea efficace. À l'aide de cette procédure, nous avons maintenant accès au mouvement local de la chaîne entière. 3) Nous avons vérifié cette procédure pour calculer une valeur pour le Tg du copolymère alternatif du l'éthylène-tétrafluoroéthylène (E-TFE), qui possède les segments qui sont présents le PVDF changé. L'ambiguïté concernant la valeur de la Tg du copolymère E_TFE peut être résolue grâce à cette approche, puisque le PVDF avec 50% de défauts régio-isomériques conduit à l'E_TFE. D'ailleurs, nous avons étudié les temps de relaxation pour la fonction d'autocorrélation de torsion au-dessus d'un large éventail de température. La dynamique locale est alors spécifiquement étudiée. L'équation Vogel-Fulcher-Tammann (VFT) est utilisée pour décrire le processus de relaxation associée aux mouvements coopératifs des segments le long de la chaîne. Nous avons également étudié le possibilité d'utiliser le Kohlrausch-Williams-Watts (KWW), fonction exponentielle étirée, afin de décrire la dépendance temporelle du processus de relaxation, ce travail a été effectué à différentes températures. Les résultats concordent bien avec les données expérimentales. L'objectif principal de cette section est d'étudier conjointement la fréquence des transitions conformationnelles et le temps de relaxation obtenu par la fonction d’autocorrelation de torsion, sur une plage importante de température, afin d’établir un entre les fréquences des transitions conformationnelles et le comportement de type VFT. Nous montrons pour la première fois qu’une relation linéaire peut être établie entre la barrière de transition conformationnelle et l’énergie d’activation effective. Nous montrons pour la première fois qu'une relation linéaire peut être établie entre la barrière de transition conformationnelle, Ea et l'énergie d'activation effective, B, responsables de la dynamique locale. Parmi les cinq phases cristallines que présente le PVDF, les cristaux α et ß présentent des propriétés particulières intéressantes et ont fait l'objet d'une attention significative. Ces deux structures cristallines sont celles que l’on rencontre le plus souvent, la phase α est la plus thermodynamiquement stable le cristal β possède des propriétés ferroélectriques. Toutefois, le comportement lors de la fusion de ces deux phases cristallines n’est pas encore totalement compris. Certains chercheurs pensent que la température de fusion de la phase β est supérieure à la phase alpha . D'autres affirment que le pic endothermique vu sur le thermogramme obtenue par calorimétrie différentielle à balayage (DSC) a été attribué par erreur à la phase β, cela à cause d’une confusion dans les références . À cet égard, le comportement de la Tm des cristaux α et β par rapport à leur épaisseur est obtenu par la dynamique moléculaire. Différents types de nanocristaux composés de chaînes de PVDF, sans ou avec 10% de régio-défauts, ayant des longueurs différentes ont ainsi été simulées dans les phases α et β. On applique l'équation de Gibbs-Thomson (G-T) afin de déterminer l'énergie de surface et l’enthalpie de fusion des nanocristaux. Les valeurs déterminées sont en accord avec les données expérimentales. Nous avons montré que le PVDF en phase β pur a une température de fusion inférieure à celle du PVDF en phase α pur. Cependant, en insérant des défauts à l'intérieur du cristal, la phase α modifiée présente une température de fusion inférieure à celle de la phase β modifiée. / Abstract : Alternating two groups, CH2 and CF2, of very different polarities along the backbone chain of polyvinylidene fluoride (PVDF) leads to very interesting properties, such as ferroelectricity. However, these properties are affected by the presence of regioisomerism defects (monomer inversion) that appear during the synthesis. During the polymerization, in addition to the Head-to-Tail (HT) sequences, CH2CF2CH2CF2, the reversed monomer units lead to formation of Tail-to-Tail (TT), CF2CH2CH2CF2, and Head-to-Head (HH), CH2CF2CF2CH2, links. The rate of this chain alteration experimentally lies between 3 and 7 %. This percentage undoubtedly brings changes in macroscopic properties. The aim of this thesis is to reveal the impact of these defects on the glass transition temperature (Tg), local dynamics and melting temperature (Tm) of PVDF by using Molecular Dynamics (MD) simulation. In amorphous phase, PVDF chains with different percentages of regiodefects were investigated: 0, 3.6, 4.1, 9.3, and 23 %. This study makes it possible to predict the experimental behavior of polymers which have not yet been synthesized. Once Tg is acquired, the relaxation of the chain can be investigated through the calculation of the activation energy (Ea) of the conformational transition. The significant conclusion is that the relaxation of the chain can be revealed by addressing the local motions. More specifically: a) We demonstrate a direct linear relationship between Tg and Ea extracted from an Arrhenius plot. This diagram corresponds to the natural logarithm of transition rates between rotameric states versus the inverse of the temperature. The slope of this curve yields directly Ea. Such a link was only speculated in the literature. b) A significant finding of this work is that the mobility of the chain can be associated with different types of bonds in PVDF with regiodefects. c) Based on the analysis of Ea for the different bond contributions, we proposed a value for the Tg of ethylene-tetrafluoroethylene (E-TFE), an isomeric polymer of PVDF with 50% regiodefects. Experimentally, the available data for the Tg of E-TFE are limited and highly variable. For example, it has been reported as varying from -108 °C to 145 °C. The ambiguity of Tg for this copolymer can be resolved with this approach. Furthermore, we studied the relaxation time associated with the torsional autocorrelation function (TACF) over a wide temperature range. The Vogel-Fulcher-Tammann (VFT) equation was used to describe the temperature dependence of the relaxation time. The Kohlrausch Williams Watts (KWW) stretched exponential function is then applied to fit the time dependence of the relaxation process at various temperatures. The results obtained from this work were found to be in good agreement with the experimental data. A particular interest in this study is the question of how the non-Arrhenius VFT of relaxation process is related to the Arrhenius behavior of conformational jump rates near the glass transition. In both cases, the energies (the conformational transition energy (Ea) and the effective activation energy (B) in VFT equation), were very close to the value of a single torsional barrier. However, in contrast to the relaxation time associated with TACF, the rates of conformational jumps show the activation energy higher than the single barrier value. We have shown that a linear relationship can be established between the conformational transition energy and the effective activation energy. In crystalline PVDF, among the five typical phases, the α and β crystals are of particular interest. The α phase is the most thermodynamically stable form and the β crystal possesses ferroelectric properties. The melting behaviour of these two crystal phases is not so clear. Some researchers believe that the melting temperature of the β phase is higher than that of the α phase. Others have claimed that the higher melting temperature of the peak in Differential Scanning Calorimetry (DSC) has been mistakenly attributed to β phase melting, due to confusion in the referencing of literature sources. In this regard, the melting temperatures of α and β crystals (with and without regiodefects) with respect to their thickness are captured by MD simulation. We then applied the Gibbs-Thomson (G-T) equation to determine the melting temperature, as well as the surface energy and enthalpy of fusion, for α and β nanocrystals. We have shown that pure β phase PVDF has a lower melting temperature than pure α phase PVDF. However, by inserting regiodefects randomly inside the crystal, the α phase with regiodefects shows a lower melting temperature than that of the β phase with regiodefects. We attributed this behaviour to the different structures of the two phases.

Carbon fiber (CF) 8-harness satin weave, T650/Neximid system of [(+45/-45)/(0/90)]2S and [(0/90)]4S layup was manufactured using resin transfer molding (RTM). The material was cut into 3-point bending specimens and treated for 24 hours in a burn oven at T=(320,350,375,400,450 & 500)°C. The material was tested according to ASTM E1640-13 using dynamic mechanical thermal analysis (DMTA). Un-treated material showed Tg levels of 384°C and 392°C for the respective layups. It was found that pre-Tg treatment between 320-375°C affected this material parameter up to similar levels as previous studies of post Tg exposure for 2h to ~420°C [4]. Subjecting the material for post-Tg exposure at 400°C showed a rapid change up to ~480°C for [(0/90)]4S laminate. Indications that this resin system could reach levels above 500°C was found for [(+45/-45)/(0/90)]2S layup. However, one of these specimens were unfit for testing. DMTA tested material for 400°C showed indications of degradation, found by a broadening of the tan delta peak. This can be put in relation to epoxy where a similar behavior appear after 24h exposure at 150°C. Furthermore, it was showed that poor quality laminate, elevated mass loss at this temperature. When the material was subjected to as high temperatures as 450°C only remaining fibers were found. At 500°C these were almost fully oxidized. 400°C data was predicted by the use of activation energy along with TG extrapolation. It was possible to show that ~1/8 out of this 8-layered structure, (½ of each surface layer), was degraded after 400°C exposure for 24h, resulting in diffusion limited oxidation (DLO). Last but not least, DLO assumptions was used to predict the storage modulus change for thermo-oxidative degradation of 400°C samples with Classic Laminate Theory (CLT). A ~4% stiffness decrease was predicted by this method. The drop is regarded as a loss in tensile stiffness of the outer damaged layer. This was compared by 3-point bending DMTA data showing a ~7% decrease. This model could thus be regarded as a contributing factor for the stiffness decrease of this complex degradation process. / Kolfiber, 8-harness satin väv, T650/NEXIMID system med [(+45/-45)/(0/90)]2S och [(0/90)]4S orientering, tillverkades via RTM. Från materialet tillverkades 3-punkts böjprover. Dessa behandlades i 24 timmar vid T=(320, 350, 375, 400, 450 & 500)°C, i en brännugn. Materialet testades i enighet med ASTM E1640-13 via DMTA. Obehandlat material visade Tg nivåer av 384°C och 392°C för de respektive uppläggningarna. Pre-Tg exponering, vid 320-375°C, påverkade Tg upp till liknande nivåer som tidigare studier, (post-Tg 2h), ~420°C [4]. När materialet utsätts för post Tg exponering under 24 timmar vid 400°C kunde man se en snabb förändring av Tg, upp till ~480°C för [(0/90)]4S laminatet. Från [(+45/-45)/(0/90)]2S laminatet kunde man dessutom se indikationer på att nivån kunde nå över 500°C. Däremot var en av dessa prov inte kvalificerad för test efter behandlingen. DMTA testat material för 400°C visade indikationer av nedbrytning, via en breddning av piken för tan-delta kurvan. Det var dessutom möjligt att se att laminat av sämre kvalitet påverkade viktminskningen signifikant högre vid denna exponering. När material utsattes för så höga temperaturer som 450°C var endas fiber kvar efter test, vilket vid 500°C nästan var fullt nedbrutna. 400°C data förutspåddes via extrapolering av TG och Arrhenius beräkning. Beräkningen ledde till en övre gräns för nedbrytningen. Vidare var det möjligt att visa att ~1/8 av dessa 8-lager bröts ner efter 24 timmars exponering vid 400°C. Nedbrytningen motsvarar ½ av vartdera ytlager via diffusions begränsad oxidation (DLO). Sist men inte minst, kunskapen om DLO användes för att förutspå styvhetsförändringen vid termo-oxiderande nedbrytning med hjälp av klassisk laminat teori (CLT). DLO antogs resultera i en volymfraktionsförändring i det yttersta lagret. Detta implementerades i CLT där man kunde beräkna en ~4% styvhetsminskning via denna modell där det yttre skadade lagret har en reducerad dragstyvhet. Från testade böjprover i DMTA kunde man se en verklig ~7% styvhetsminskning för samma exponeringsvillkor. Modellen kan därmed ses som en bidragande del av denna komplexa nedbrytningsprocess.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2014-09-24T14:14:57Z No. of bitstreams: 2 Reis, Pamela Cristina de Sousa Guardiano.pdf: 1296512 bytes, checksum: 257e678ee16ea253856f4f88bba00934 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Cláudia Bueno (claudiamoura18@gmail.com) on 2014-09-25T11:39:13Z (GMT) No. of bitstreams: 2 Reis, Pamela Cristina de Sousa Guardiano.pdf: 1296512 bytes, checksum: 257e678ee16ea253856f4f88bba00934 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-09-25T11:39:13Z (GMT). No. of bitstreams: 2 Reis, Pamela Cristina de Sousa Guardiano.pdf: 1296512 bytes, checksum: 257e678ee16ea253856f4f88bba00934 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-02-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This study aimed to develop general microcapsules containing turmeric oleoresin and cluster derived from turmeric suspended in canola oil from concentrated whey protein, encapsulating material, and evaluate their antimicrobial activity. Turmeric gained fresh in the municipality of Mara Rosa underwent slicing and dehydration in an oven with air circulation. Obtained as a powder after successive washes with ethanol generated containing the ethanol extract of turmeric oleoresin which was rotaevaporado generating the turmeric oleoresin. This extract was subjected to vacuum filtration in order to remove solid fractions, and this filtration gave a cluster of turmeric. Both the extract containing oleoresin such as agglomerated product obtained by filtration were suspended in canola oil and used as core material for developing microcapsules. The microcapsules obtained had good sphericity concluding that the protein concentrate of whey was a good encapsulating material to the core studied. The microcapsules and free oleoresin extract were taken for analysis of antibacterial activity using agar diffusion test and found that the extract of turmeric oleoresin can be regarded as a potential antimicrobial agent, none of the microcapsules showed antimicrobial activity against fungus, but against the bacteria showed bacteriostatic action. We evaluated the behavior of the microcapsules determining their sorption isotherms, thermal stability and glass transition temperature. Before the study concluded that: the microcapsules oleoresin showed good thermal stability at temperatures that did not exceed 225 ° C, while the turmeric powder had good stability under temperatures slightly higher, up to 250 ° C, and these results do not conclusive, necessitating characterization studies of the patterns. / Este trabalho teve por objetivo geral desenvolver microcápsulas contendo oleorresina de cúrcuma e aglomerado derivado da cúrcuma suspensos em óleo de canola, a partir de concentrado de proteína do soro do leite, material encapsulante, e avaliar a sua atividade antimicrobiana. Cúrcuma in natura adquirida no município de Mara Rosa foi submetida a fatiamento e desidratação em estufa com circulação de ar. Obteve-se um pó que, após sucessivas lavagens com etanol gerou o extrato etanólico contendo oleorresina de cúrcuma que foi rotaevaporado gerando a oleorresina de cúrcuma. Esse extrato foi submetido a uma filtração a vácuo, a fim de se retirar frações sólidas, e obteve-se dessa filtração um aglomerado de cúrcuma. Tanto o extrato contendo oleorresina quanto esse produto aglomerado obtido pela filtração foram suspensos em óleo de canola e utilizados como material de recheio para desenvolvimento de microcápsulas. As microcápsulas obtidas apresentaram boa esfericidade concluindo que o concentrado proteico do soro de leite constituiu um bom material encapsulante para o núcleo estudado. As microcápsulas e o extrato de oleorresina livre foram levados para análise de atividade antibacteriana através de teste de difusão em ágar e concluiu-se que o extrato de oleorresina de cúrcuma pode ser tido como um agente antimicrobiano em potencial; nenhuma das microcápsulas apresentou ação antimicrobiana contra o fungo, mas contra a bactéria apresentaram ação bacteriostática. Foi avaliado também o comportamento das microcápsulas determinando suas isotermas de sorção, estabilidade térmica e temperatura de transição vítrea. Diante do estudo concluiu-se que: as microcápsulas de oleorresina apresentaram boa estabilidade térmica sob temperaturas que não ultrapassassem 225°C; enquanto que as de aglomerado de cúrcuma apresentaram boa estabilidade sob temperaturas um pouco maiores, até 250°C, sendo estes resultados não conclusivos, necessitando-se de estudos de caracterização dos padrões.

Polymeric systems near their glass transition are known to exhibit heterogeneous dynamics that evolve both over space and time, yet many of the underlying principles of these dynamics are still poorly understood. In this thesis, experimental single molecule studies aimed at uncovering the dynamics of polystyrene near its glass transition temperature are described. In a first approach, the influence of temperature on the timescales associated with dynamic heterogeneity – also referred to as exchange times – are identified by following the dynamics of a fluorescent perylene diimide probe embedded in a high-molecular weight polystyrene host. No clear influence on the lifetime of dynamics is found in the temperature regime Tg to Tg + 10 K. In a second study, heterogeneous dynamics are investigated in the context of molecular weight and fragility. In a similar experimental approach to that of the first study, two fluorescent dyes are utilized to report on the rotational dynamics of low- to high-molecular weight polystyrene hosts. In accordance with previous reports, the stretching exponent, β, is found to be correlated with the system’s molecular weight, even on a single molecule level. However, no clear correlation with the system’s exchange time was found. In a final study, several single molecule approaches aimed at uncovering the dynamics in confined polystyrene films are described. As no evidence for previously-described mobile surface molecules has been found, this final chapter is meant to provide a basis for future single molecule studies in confined systems.

The aim of this research is to understand the solid state physical properties of inulin in regards to the spray-drying treatments. In this context, inulin powders were produced by pilot spray-drying a commercial inulin dispersion under various feed (Tfeed) and inlet air (Tin) temperatures. More particularly, the amorphous and crystalline properties of the powders were studied by developing different fine characterization tools, such as modulated differential scanning calorimetry or powder X-ray diffraction. When the temperature of the inulin water systems increased, the crystallinity of the powder decreased. To a smaller extent, this tendency is also observed with the increase of the inlet air temperature of the spray drier. For example, an amorphous powder is obtained with a Tfeed of 90°C whatever the Tin (comprised between 120 and 230°C); whereas for a Tfeed of 80°C, a Tin of 230°C is necessary to obtain the same result. Adsorption isotherms were established on four powders covering a large range of crystallinity (crystallinity index from 0 to 92). The Guggenheim Anderson de Boer model was fitted to the experimental data. As the water content of the powders increased, the glass transition of inulin decreased. When the Tg droped below the storage temperature (20°C for example), the powders crystallized and underwent clumping phenomenon. Under these conditions, a continuous hard mass was observed for the amorphous powders; while their semi-crystalline counterparts were agglomerated but friable. To understand these changes, a kinetic study of the physical properties evolution and stability of an amorphous powder as a function of its water content was realized. These results allowed to correlate the Tg water content relationship to the evolution of the powders behaviour, such as stickiness or hardening during storage.

The flexible substrate was fabricated by BaTi4O9 mixed with O-Cresol Novolac Epoxy, polyether imide or surface active agents. The electrical and physical characteristic measured had been finished. The dielectric property influence of substrate was changed from percentage of BaTi4O9. The dielectric constant model was used by Jayasundere and Smith equation (J. S. eq.) and Lichtenecker equation (L. eq.) The study of crystalline grain, orientation and phase transfer temperature was used by SEM, XRD, and DSC, respectively. The dielectric constant and dielectric loss tangent of the composite was measured using an HP4294A impedance analyzer. The TM mode calculated by resonate frequency of the composite was measured using an HP4156C network analyzer. The dielectric constant was obtained to TM mode at high frequency. The result was showed that dielectric constant at low frequency of BaTi4O9, OCN Epoxy and PEI are 57, 5.8 and 3.65, respectively. OCN Epoxy is better than PEI of electrical characteristic. However, OCN Epoxy is not flexible. For this reason, the PEI was focused on electrical property at high frequency. The BaTi4O9 exhibited a dielectric constant of 39 at frequency during 3~10 GHz. The dielectric constant was measured of 10 at frequency during 2~16 GHz with 70 wt% PEI composite. The dielectric constant is higher than FR-4 substrate to 6.4 of the composite. The low dielectric constant is obtaining to reduce stuffing.