Universiẗat, Diss.--Marburg, 1995.

Frankfurt (Main), Univ., Diss., 2008 / Erscheinungsjahr an der Haupttitelstelle: 2007

Zugl.: Stuttgart, Univ., Diss., 2009.

Fibras são definidas como o conjunto formado de filamentos orientados na direção da cadeia molecular e são parte fundamental na vida diária do ser humano, encontradas de várias formas, tais como filamentos, fios, feixes, cordas, tecidos, compósitos, revestimentos, entre outras. Elas abrangem diversas áreas, tais como civil, mecânica, elétrica, eletrônica, militar, naval, náutica, aeronáutica, saúde, medicina, ambiental, comunicação, segurança, espacial, entre outras. A fibras são divididas em duas classes distintas, naturais e químicas, que compõem as subclasses sintéticas e artificiais. Podem ser produzidas de vários materiais, tais como lã, algodão, raion, linho, seda, rocha, náilon, poliéster, polietileno, polipropileno, aramida, vidro, carbono, aço, cerâmica, entre outros. Em nível global, as fibras químicas correspondem a 59,9% do mercado, sendo as fibras sintéticas tipo poliéster as mais utilizadas, com 63%. Necessidades vitais têm levado ao desenvolvimento de fibras multifuncionais e o foco mudou nos últimos dez anos com a utilização da nanotecnologia para fibras de responsabilidade ambiental e fibras inteligentes. O estudo das propriedades mecânicas e dos mecanismos de fratura das fibras é de grande importância para caracterização e entendimento das causas de falhas. Para este propósito foram selecionados tecidos fabricados com fibras sintéticas de alto desempenho do tipo náilon e poliéster, utilizadas em produtos de engenharia tais como pneus, correias, mangueiras e molas pneumáticas, as quais foram analisadas em cada etapa de processamento. Amostras das fibras foram retiradas de cada etapa de processamento para análise por ensaios destrutivos de tração e microscopia eletrônica de varredura. Os resultados de análise das propriedades mecânicas mostraram perda de resistência por temperatura e tensões multiaxiais durante as etapas de processamento da fibra. Por meio de ensaios de microscopia foi possível determinar contaminações, manchas superficiais, deformações plásticas, delaminações, variações nas faces de fratura dos filamentos e analisar, na interface fibra-borracha, o nível de adesão. Estas irregularidades e variações são causadas durante as etapas inerentes ao processo de fabricação. / Fibers are groups formed by molecular-chain-oriented filaments. Fibers play a fundamental role in human beings daily life and they can be found in several forms and geometries, such as filaments, yarns, beams, rope, fabric, composite, coatings, others. They are used in various segments such as civil, mechanical, electrical, electronics, military, naval, nautical, aviation, health, medicine, environment, communications, safety, space, others. Fibers are divided into two distinct classes: natural and chemical ones, which cover synthetic and man-made sub-classes. They can be produced from several materials, such as wool, cotton, rayon, flax, silk, rock, nylon, polyester, polyethylene, poly-propylene, aramid, glass, carbon, steel, ceramic, others. Globally, the participation of chemical fibers corresponds to approximately 59,9%, and the synthetic fiber polyester, the most used one, represents approximately 63% of the world market. Vital needs have led to the development of multi-function fibers and the focus has changed in the last 10 years with the use of nanotechnology for environmental responsibility and smart fibers. The study of mechanical properties and fracture mechanisms of fibers is of great relevance for characterization and understanding of causes as consequence of failures. For such reason, it was selected technical fabrics made of high performance synthetic fiber nylon-and-polyester type, used in engineered products such as tires, belts, hoses and pneumatic springs, which have been analyzed in each processing phase. Fiber samples were extracted after each processing phase to be analyzed, by traction destructive tests and scanning electron microscopy. The results of analysis of mechanical properties showed loss of resistance to temperature and multi axial stress during fiber processing phase. Through microscopy tests, it was possible to find contamination, surface stains, plastic deformations, scaling, variations in the fracture faces of the filaments and analyze in the fiber-rubber interface, the level of adhesion. These irregularities and variations are caused during the stages of the process.

O trabalho investiga a influencia dos parametros de processo: relacao D/Y e numero dos discos do agregado de texturizacao nas propriedades de frisagem dos filamentos de poliester texturizados por falsa torcao. Sao realizados ensaios numa texturizadeira industrial simulando diferentes niveis dos fatores D/Y e numero de discos.Analises estatisticas sao apresentadas e comprovam a influencia dos fatores nas caracteristicas de frisagem com nivel de confianca de 5%. Verifica-se que a combinacao de D/Y elevado com numero de discos elevado aumenta os valores dos parametros de frisagem do fio texturizado. / The work investigates the influence of process parameters: the factor D / Y and the aggregate number of disks in the texturing properties crimping of textured polyester filaments for false twist. Tests were performed in an industrial texturing machine simulating different levels of factors D / Y and number of discs. Results of statical analyses are presented and show the influence of factors on the characteristics of crimping with a confidence level of 5%. It is found that the combination of D / Y with a high number of discs increases the high values of the parameters of the crimp textured yarn.

No description available.

No description available.

Linear thermoplastic polyesters are commonly used in high volume applications such as food containers, films and textile fibers. The physical and mechanical properties of these materials are well documented and are a function of chemical structure and morphology (e.g. semi-crystalline, amorphous, etc.). Polyesters, as are many organic polymers, are quite flammable. Polydimethylsiloxane homopolymer exhibits low mechanical strength and, even at high molecular weight, exists as a viscous fluid rubbery gum due to its low glass transition temperature of approximately -123°C. However, one of the many attractive properties of this polymer is its relatively low flammability and if properly designed, organic "sand-like" silicates are produced in oxidizing atmospheres at elevated temperatures (e.g. 500-700°C). This thesis discusses the synthesis and characterization of novel, high molecular weight cycloaliphatic and aromatic polyester/ poly(dimethylsiloxane) segmented copolymers. The cycloaliphatic copolymers were synthesized via a melt process using a high trans content 1,4 dimethylcyclohexanedicarboxylate, and 1,4 butanediol or cyclohexanedimethanol, while the partially aromatic systems were synthesized using dimethyl terephthalate and butanediol. Primary and secondary aminopropyl terminated poly(dimethylsiloxane) oligomers of controlled molecular weight were endcapped with excess diester to form an amide linked diester terminated oligomer. The latter was then incorporated into the copolymer via melt transesterification to afford a multiphase segmented copolymer. Selected compositions showed enhanced ductility and hydrophobic surface modification. The polysiloxane segment was effeciently incorporated into the copolymers and was unaffected by the transesterification catalyst under typical reaction conditions. The homopolymers and copolymers were characterized by solution, thermal, and mechanical, and surface techniques. The segmented copolymers were demonstrated to be microphase separated as determined by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and transmission electron microscopy. The surface of the copolymers was enriched with the polysiloxane segment as evidenced by contact angle analysis. Thermal gravimetric analysis of the segmented copolymers containing identical amounts of PDMS, but varying in the primary or secondary nature of their amide linkages, exhibited quantitatively identical char yields and weight loss behavior. The segmented copolymers exhibited char yields in air superior to those of their respective homopolymers. Additionally, aromatic poly(tetramethyleneoxide) (PTMO) based polyether/polyester segmented copolymers were modified with poly(dimethylsiloxane). DMA revealed an apparent shift (higher Tg) of the PTMO segment reflecting an increase in phase mixing with the "hard" polyester segment, possibly induced by the hydrophobic PDMS phase. / Master of Science

L'Imagerie par Résonance Magnétique (IRM) est à l'heure actuelle la technique de visualisation préférentiellement choisie par les chirurgiens. Cependant, cette technique ne permet pas de visualiser des prothèses à base de polymères, qu'elles soient dégradables ou non. Afin de mieux évaluer la fixation, l'intégration tissulaire et le devenir de l'implantation de ces prothèses polymères, il serait souhaitable qu'elles soient visibles par IRM. Ce travail présente donc la conception et la synthèse de copolymères biocompatibles visibles par IRM destinés à être introduit dans la composition de prothèses pour applications temporaires ou permanentes. En utilisant la modification chimique en position alpha de fonction ester décrite précédemment par notre laboratoire, nous avons greffé de façon covalente et par une liaison stable un chélate du gadolinium (le DTPA) sur la chaîne de la PCL (dégradable) et du PAM (non dégradable). Le gadolinium a ensuite été complexé par le DTPA greffé préalablement. Ces nouveaux copolymères ont été caractérisés par RMN et CES, et le taux de gadolinium évalué par ICP-MS. Des images d'IRM ont été réalisées in vitro et in vivo sur des appareils contenant des aimants de 7 Teslas (recherche) et 1,5 Teslas (clinique). Ces images montrent qu'un treillis en polypropylène enduit de copolymère greffé par un complexe DTPA-gadolinium est visible par IRM, ce qui laisse entrevoir un large champ d'applications pour ce type de composé. / Magnetic Resonance Imaging (MRI) is currently the visualization technique that surgeons preferentially choose. However this technique does not allow the visualization of polymer-based prosthesis, whether they are degradable or not. In order to best assess adhesion, tissue integration and the future of implantation of these polymer prosthesis, it would be advisable to make them visible in IRM. This work presents the conception and the synthesis of biocompatible copolymers visible in IRM meant to be implanted under the form of prosthesis for temporary or permanent applications. Using the chemical modification in alpha position of ester function, previously described by our laboratory, we grafted a gadolinium chelate, in a covalent way and forming a stable bond on PCL (degradable) and PMA (non degradable) backbone. Gadolinium was then complexed by DTPA previously grafted. Those new copolymers were characterized with NMR and SEC, and the rate of gadolinium was assessed by ICP-MS. MRI images were taken in vitro and in vivo on devices containing 7-Teslas (research) and 1,5 Teslas (clinical) magnets. These images show a poly(propylene) mesh coated with grafted copolymer containing complex gadolinium which is visible in MRI. It will consequently improve the prospects of applications for this kind of MRI-visible compound.

Afin d'optimiser les propriétés d'un composite polymère chargé, il est possible de procéder à un greffage de la charge afin de la rendre compatible avec le milieu continu dans laquelle elle est dispersée. Le sujet de recherche consiste à étudier et optimiser le mécanisme de greffage de molécules organiques à la surface de charges minérales.Développé il y a quelques années par la société GTI Process (groupe Mader), le "giral" est une formulation qui permet d'une part d'obtenir une bonne dispersion entre une charge et une matrice polymère et d'autre part d'augmenter les propriétés mécaniques du matériau composite final. Il se compose d'un silane, d'un acide méthacrylique et d'un dispersant. Toutefois, le mécanisme existant lors de l'ajout de giral dans une formulation charge/résine n'a pas été identifié. Nous nous sommes proposé de le comprendre. Après avoir identifié les interactions entre la surface de la silice et les constituants du giral, il nous a paru intéressant de faire évoluer la formulation du dispersant.Dans un premier temps, ce mécanisme a été étudié sur une charge témoin bien maîtrisée : la silice.La silice retenue a l'avantage de posséder une surface spécifique importante. Des analyses thermogravimétrique et infrarouge ont été réalisées sur différents échantillons (synthétisés à partir de silice et d'un ou plusieurs constituants du giral) afin de déterminer les espèces adsorbées ou greffées à la surface de la silice. Des analyses RMN du solide 13C et 29Si ont également été réalisées dans le but de déterminer les liaisons mises en jeu. En parallèle, des études en CGI (Chromatographie Gazeuse Inverse) ont été menées.Dans un second temps, des nouvelles structures ont été développées pour améliorer le dispersant contenu dans la formulation du Giral puis la formulation en synthétisant un seul composé qui regroupe toutes les fonctionnalités requises pour disperser la silice dans une résine polyester. De plus, ces nouvelles structures vont permettre d’augmenter les propriétés mécaniques du matériau composite final. Tous les composés synthétisés, dans ce travail, ont un squelette polymère qui est la polycaprolactone. L’architecture, la composition, la taille et la structure de ces polymères ont été optimisées suivant la charge à disperser. Nous avons ainsi synthétisé une large gamme de dispersants modèles fonctionnalisés et étudié leur comportement dans l'application. D'autre part, seules les méthodes de synthèse en masse, plus adaptées pour une production industrielle, ont été retenues. Ces polymères ont tout d'abord été synthétisés en laboratoire puis dans le milieu industriel. Une fois les polymères synthétisés, plusieurs essais ont été réalisés pour connaître leur influence au niveau des propriétés mécaniques du matériau composite final, déterminer les structures les plus adaptées pour répondre aux contraintes mécaniques, et connaître les quantités nécessaires pour obtenir les meilleurs résultats. Des mesures de viscosité et des essais mécaniques (essais de traction et de flexion 3 points) ont été réalisés. L'utilisation de ces composés développés au cours de ce travail de thèse ont permis de diminuer la viscosité d’une résine polyester chargée et ainsi de pouvoir augmenter le taux de charge. De plus, les faciès de rupture ont été observés par microscopie électronique à balayage afin d'observer la cohésion entre les charges et la matrice polymère du composite. La rupture apparaît au niveau de la charge et du polymère. L'efficacité de ces nouvelles structures dans l’application s'est avérée comparable, voire meilleure par rapport au dispersant de référence et au giral. / To increase the properties of a composite based with polymer and tiller, it is possible to modify the tiller surface to make it compatible with the polymer in which it is dispersed. The aim is to study and optimize the mechanism of organic molecules grafting on mineral fillers surface. Developed several years ago by GTI Process (Mader group), the "giral" i s a formulation that allows a good dispersion between the tiller and the polymer matrix and also an increase of the final composite material mechanical properties. "Giral" is composed of a silane, a methacrylic acid and a dispersant. However, its mechanism with a mixture based on tiller and pol yester resin has not been identified, we proposed to understand it. After identifying the interaction between the surface of silica and "giral" components, it seemed interesting to modify the dispersant. In a first part, the "giral" mechanism has been studied on silica which is a well-known tiller. Silica used has a high specific surface area. Thermogravimetric and infrared analysis have been performed on different samples (synthesized from silica modified by one or more "giral"components) to determine the adsorbed or grafted species on silica surface. NMR analyses of 13C and 29 Si solid and Inverse gas chromatography studies were also conducted. In a second part, new structures have been developed to improve the dispersant in the "giral" formulation and the formulation itself by synthesizing a single compound that includes all the features required for the dispersion of silica in polyester resin. Moreover, these new structures will help to increase the mechanical properties of the final composite material. All compounds synthesized in this work, have a polymer backbone which is polycaprolactone. The architecture, composition, size and structure of these polymers were optimized according to the tiller used. We have synthesized functionalized dispersants and studied their behavior in the application. On the other hand, only syntheses by mass, more suitable for industrial production, were selected. These polymers have been first synthesized in the laboratory and then in industry. Once the polymers synthesized several tests were done to determine their influence in the final composite material mechanical properties, the most appropriate structures to mechanical stress, and the amounts required for best results. Viscosity measurements and mechanical tests were done. These new dispersants developed have reduced the viscosity of the mixture based on polyester resin and tiller, and thus can increase the tiller rate. Furthermore, the fracture surfaces were observed by scanning electron microscopy to observe cohesion between the tiller and the polymer matrix. The effectiveness of these new structures in the application are comparable or even better to the "giral" formulation.