A conformação de dispositivos médicos implantáveis a partir de uma blenda exige o desenvolvimento de um produto com propriedades próximas do comportamento ideal, combinando propriedades térmicas e mecânicas e boa resposta tecidual. O Poli (ácido láctico-co-glicólico) (PLGA) e o Poli (isopreno) (IR) foram escolhidos como componentes da blenda com finalidade de promover boa biocompatibilidade e características mecânicas especificas. As blendas foram obtidas por dissolução dos polímeros em solvente orgânico, seguida de secagem. Para determinar a influência do teor de IR sobre as propriedades da blenda, foram realizados ensaios de espectroscopia na região de infravermelho por transformada de Fourier (FTIR), calorimetria diferencial de varredura (DSC), análise dinâmico-mecânica (DMA), microscopia óptica por luz polarizada (POM), análise de dureza, ensaio de tração e análise de viabilidade celular. A presença de IR na blenda provocou alteração na estrutura molecular semi-cristalina do PLGA, bem como influenciou o comportamento mecânico analisado a partir da curva tensão-deformação do material. A blenda se mostrou biocompativel em ambiente celular e em ensaios preliminares em animais, apresentando potencial para aplicação como biomaterial. / The conformation of an implantable medical device from a polymeric blend requires the development of a product with properties as close as possible of ideal behavior with the combination between thermal and mechanical properties and good tissue response. The poly (lactic-co-glycolic acid) (PLGA) and the poly (isoprene) (IR) were chosen as the blend components to promote good biocompatibility and specific mechanical characteristics. The blends were obtained by dissolution of polymers in organic solvent, followed by drying. In order to determine the IR content influence over the blend properties, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), polarized light optical microscopy (POM), hardness analysis, tensile test and cell viability test were carried out. The IR presence caused changes in semi-crystalline molecular structure of PLGA, as well as actuated over the mechanical response analyzed on material’s stress-strain curve. The blend showed itself biocompatible at cellular environment and at preliminary animal tests, presenting potential for application as biomaterial.

As ferramentas termo-analíticas, tais como a calorimetria exploratória diferencial (DSC) e a análise termogravimétrica (TGA), são os métodos usualmente utilizados para a verificação preliminar acerca da existência de interações entre fármacos e adjuvantes. Neste trabalho, foram verificados a equivalência entre a quercetina, empregada como matéria-prima, e a quercetina referência, seus comportamentos térmicos e a possível existência de interações entre esta substância e adjuvantes tecnológicos usualmente empregados no desenvolvimento de formas farmacêuticas sólidas e semi-sólidas. A evidência de interações foi investigada por análise de misturas físicas binárias sólidas da quercetina e o adjuvante. Os adjuvantes utilizados foram o ácido esteárico, álcool estearílico, celulose microcristalina, croscarmelose sódica, dióxido de silício coloidal, estearato de magnésio, lactose, manitol, monoestearato de glicerila, polissorbato 80, povidona, propilenoglicol, talco e vaselina sólida. A influência do processo de secagem por aspersão sobre as características da quercetina isolada e em presença do adjuvante de secagem dióxido de silício coloidal também foi avaliada. Os perfis espectroscópicos e cromatográficos das duas amostras de quercetina foram sobreponíveis, enquanto que o comportamento térmico da quercetina matéria-prima, obtido por DSC, não se mostrou equivalente ao da referência, pressupondo diferentes forma de cristalização ou solvatação. Para as misturas físicas, apenas aquelas contendo estearato de magnésio e lactose apresentaram indícios de interação verificados por DSC e confirmados por TGA, mas não ratificados por espectroscopia no infravermelho. O processo de secagem por aspersão modificou o perfil térmico da quercetina, enquanto o produto seco por aspersão contendo adjuvante de secagem apresentou resultados semelhantes aos obtidos para a mistura física com as mesmas substâncias.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.

L’effet du confinement de la phase amorphe lors de la cristallisation du poly(éthylène téréphtalate) et du poly(acide lactique) a été étudié à multi-échelles. Ces polymères peuvent exister sous forme amorphe et semi-cristalline. La relation entre la microstructure et les propriétés viscoélastiques des matériaux a été mise en évidence par les expériences en diffusion des rayons X aux petits angles (SAXS) et aux grands angles (WAXS), en Calorimétrie différentielle à balayage (DSC), en traction, en analyseur mécanique dynamique (DMA) et en nanoindentation. La différence de la structure moléculaire du PET et du PLA est essentielle pour leur comportement physique et mécanique. Au cours de la cristallisation, une autre phase amorphe dont le comportement mécanique est plus rigide que la phase amorphe traditionnelle a été formée. La DSC permet de quantifier la dépendance de la fraction de cette phase amorphe rigide en fonction du taux de cristallinité. La technique de diffusion des rayons X permet d’étudier l’évolution de la microstructure (dimension de cristallites, épaisseur des phases) lors de la cristallisation. Le comportement mécanique des polymères a été étudié à différentes échelles. Les essais de DMA permettent non seulement d’étudier le comportement viscoélastique macroscopique des polymères mais aussi de quantifier les propriétés viscoélastiques de chaque phase amorphe via leur température de transition vitreuse. Cela a été utilisé comme données d’entrée dans des modèles micromécaniques. La nanoindentation permet de mesurer les propriétés mécaniques du matériau à son extrême surface. Dans la dernière partie, une approche des propriétés mécaniques macroscopiques des matériaux a été réalisée par des modèles micromécaniques d’homogénéisation en se basant sur la morphologie matrice-inclusion. / The signature of confinement effect onto the mechanical properties of the amorphous phase during crystallization of two polymers, Polyethylene terephthalate (PET) and poly(lactic acid) (PLA) was investigated at multi-scale. The two polymers have the advantage of being either in bulk amorphous or in semi-crystalline state. The relation between the microstructure and the viscoelastic properties of materials is put light on by the experiments of X-Ray Scattering, differential scanning calorimetry (DSC), by tensile strength tests, by dynamic mechanical analysis (DMA) and by nanoindentation. The difference in molecular structure of PET and PLA is essential for their physical and mechanical behavior. During crystallization, the second amorphous phase whose mechanical behavior is more rigid than conventional amorphous phase was formed. DSC is used to quantify the rigid amorphous fraction dependence on the crystallinity. The technique of X-ray scattering is used to study the evolution of the microstructure (crystallite size, lamella thickness) during crystallization. The mechanical behavior of materials was studied at different scale. DMA tests allow not only to study the macroscopic behavior of viscoelastic polymers but also to quantify the viscoelastic properties of each amorphous phase through their glass transition temperature. This was used as input data in micromechanical models. Nanoindentation is used to measure the mechanical properties of the materials at the extreme surface. In the last part, the homogenization micromechanical modeling was performed based on the matrix - inclusion morphology in order to predict the macroscopic mechanical behavior laws of materials.

Melding is a novel process which offers a promising route to creating seamless bonds, by partially curing two laminates in a controlled manner using a Quickstep chamber and subsequently co-curing them. Previous research has focused on melding lap joints in the x-y plane of a composite, whereas this study investigates through-thickness melding, or melding in the z-plane of a composite. In this process, two composite stacks were exposed to heat from one side and actively cooled on the other through the z-axis. The two semi-cured parts were then co-cured creating a monolithic part with a seamless bond.The initial stage of the project developed the semi-curing process. After unsuccessful attempts to produce a semi-cured part in a general purpose Quickstep chamber, due to excessive heat transfer, the process was moved to a hot press with independently controlled platens. The hot press succeeded because the platens were separated from each other by the composite plate, unlike the Quickstep bladders which, as they are designed to conform to the part, came into contact allowing for heat transfer. Thermocouples were embedded every 15 plies to quantify the temperature profiles generated through the laminate stack.The next stage of the project developed a process of joining the semi-cured panels to form a through-thickness melded part. The final process involved constraining the sides of the panel with cork edge dams and inserting woven glass fabric at the corners to allow for gasses to escape. However, the outer parts of the fully melded panel exhibited excessive porosity which had an adverse effect on mechanical properties. For example, whereas tensile and flexural moduli measured for material from the edges of the panels were comparable to values reported in literature, the properties of samples from the middle of the panels deteriorated significantly due to the porosity. Mode I interlaminar fracture energy was approximately 10% lower than values measured for panels fabricated in an autoclave.The entire curing process, from semi-curing to a fully melded panel, was characterized extensively. Differential scanning calorimetry was used to determine the degree of cure and values of glass transition temperature (Tg). The degree of cure of the material exposed to the hot side was approximately 50%, the middle 25%, whereas the cold side was only 15% cured. A corresponding Tg profile through the curing process was developed in which the Tg varied from 0 degrees C for the uncured resin to 245 degrees C in highly cured samples. After melding the sample, the degree of cure was found to be in excess of 99%. Rheological studies were carried out to determine the effects of the semi-curing process on resin flow during the melding cycle.Results showed that there was a large transition zone between uncured plies and solid (cured) plies.This thesis demonstrated the broad feasibility of through-thickness melding as a process to create thick composite laminates. However, the complexity of the process gives rise to thermal and rheological phenomena which affect the structural and chemical properties of the fully melded part. The process must therefore be engineered with these factors in mind in order to create a high quality part.

Lead's uptake on magnetite has been quantitatively evaluated in the present study at a temperature of 200°C and pH of 8.5 with lead concentrations ranging from 5 ppm to175 ppm by equilibrium adsorption isotherms. The pH independent sorption behavior suggested lead sorption due to pH independent permanent charge through weak electrostatic, non-specific attraction where cations are sorbed on the cation exchange sites. The permanent negative charge could be a consequence of lead substitution which is supported by increase in the lattice parameter values from the X-ray diffraction (XRD) results. Differential scanning calorimetry (DSC/TGA) results showed an increase of exothermic (magnetite to maghemite transformation) peak indicating substitution of lead ions due to which there is retardation in the phase transformation. Presence of outer sphere complexes and physical sorption is further supported by Fourier transformed infrared spectroscopy (FTIR). None of the results suggested chemisorption of lead on magnetite.

Content: Pre-treatments are widely used during tanning processes as to improve the performance of the main tannage. Synchrotron small-angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) were used to study four common types of pre-treatments, viz. monodentate complexing agent (sodium formate, SF), chelating agent (disodium phthalate, DSP), covalent cross-linker (glutaraldehyde, GA) and nanoclay (sodium montmorillonite, MMT) about their effects on chromium-collagen cross-linking reaction during tanning. Based on the results, the performance of chromium-collagen cross-linking with and without pre-treatments was presented considering five aspects: cross-linking, the level of hydration, hydrothermal stability, uniformity through leather cross-section and the uptake of chrome. Comparing to the original ThruBlu chrome tanning, at the same chrome offers, leather pre-treated using SF, DSP and MMT showed improved hydrothermal stability, uniformity and the level of hydration, while GA showed decreased hydration. All of the pre-treatments reduce surface fixation by decreasing the reactivity of chromium with collagen. Changes in the reaction performance can influence the properties of the leather products as well as the efficiency of the leather manufacturing processes. Insights into the structural changes of collagen during tanning with varied reaction conditions can guide the design of novel, benign tanning processes to reduce environmental impact. Take-Away: 1. Uniformity of the hydrothermal stability through leather cross-section were improved by all of the studied pre-treatments. 2. Reactivity of chromium to cross-link with collagen was reduced as a result of the complexing, covalent cross-linking, or preferential adsorption. 3. Complexing agents and nanoclay pre-treatments tend to retain collagen bound water, while covalent cross-linker causing decrease in the level of hydration of collagen.

The master thesis deals with DSC measurments a calculation of kinetic parameters. In the theoretical part, iron alotropy is briefly described, followed by a description of the DSC analysis itself. The thesis also includes division and derivation of isoconversional methods for calculating the activation energy. In the experimental part, a series of measurments is perfomed on pure iron prepared by Cold Spray method. In the paper the influence of deformation on the Curie temperature of the magnetic transformation in -Fe and transformation > is investigated. The activation energy is calculated for transformation > for different degrees of deformation. The degree of deformation is monitored by channeling contrast.

Alloy NiTi with nearequiatomic composition of nickel and titan belongs to a group of metal materials with a shape memory effect (Shape memory alloys). NiTi alloys are a guite attractive materials not only as practical shape memory alloys with hight strenght and ductility but also as those exhibiting unique physical properties. The production of these matrerials is complying with chemical composition. Final charakteristics of alloy are influenced by these bounderies and also by mechanical-heat treatment. This work deal with DSC evaluation of homogenity of ingot structure of NiTi alloy containing 50,8 at.% Ni. The alloy was melted in Y2O3 cricible. In the end the results of DSC method are compared to the microstructure of alloy obtained by SEM and TEM methods.

This master thesis deals with characterization of two black and white products based on ethylene-propylene-diene rubber (EPDM) used for skating rink. Products marked with A and are different in their diameter of circular tubes trough which cooling medium passes and also in the distance of these tubes. Both of materials were characterized in order to determine whether it is the EPDM and how are they different. The characterization methods were used: differential scanning calorimetry, thermogravimetric analysis, attenuated total reflectance Fourier transform infrared spectroscopy, tensile test, swelling test, thermooxidative test. The composition of both materials, including fillers and others additives is almost the same but difference is in structure of EPDM and probably also in interaction with fillers, what exhibits different mechanical properties, thermooxidative stability and thermal capacity. These differences which have been found are essential for long-term use properties of both materials.