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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
551

Sustainable and Environmental freindly fibers in Textile Fashion (A Study of Organic Cotton and Bamboo Fibers)

ADNAN ALI, MUHAMMAD, IMRAN SARWAR, MUHAMMAD January 2010 (has links)
In recent times sustainability is a leading characteristic of textile fashion products. Textile fashion companies are focusing more on sustainable products these days, so that they can meet the environmental and social aspects. For getting competitive advantage in fashion business the companies have to take care of social, political and economical issues, and they must be aware of current trends of the market. Sustainable fibres provide solution for the companies facing issues regarding environmental problems; these fibres are also favorable to meet the market demands of quality products these days. The main objective of this report is to use the sustainable materials in fashion garments; the report contains rich information about two natural sustainable fibres (organic cotton and Bamboo), that describes the brief history, biography, development, processing, application and uses of these fibres. This report briefly describes the advantages and disadvantages of these fibres and underlines the usage of these fibres by famous designers, and by many top brands and fashion companies for their competitive advantage and brand image. The report highlights the potentials of using these materials in textile fashion products and describes that high fashion and quality products can be made by these products to guarantee the environmental and social standards / Program: Magisterutbildning i Applied Textile Management
552

Estudo da modificação superficial de fibras de carbono por meio de tratamentos a plasma para o aumento da adesão na interface de compósitos fibra de carbono/PPS /

Santos, Alberto Lima. January 2015 (has links)
Orientador: Leide Lili Gongalves da Silva Kostov / Coorientador: Edson Cocchieri Botelho / Coorientador: Mario Ueda / Banca: Rogério Pinto Mota / Banca: Michelle Leali Costa / Banca: Mirabel Cerqueira Rezende / Banca: Carina Barros Mello / Resumo: Este trabalho refere-se ao processamento de compósitos termoplásticos obtidos a partir de fibras de carbono tratadas por meio de técnicas assistidas por plasma. Os tratamentos empregados foram Descarga Elétrica com Barreira Dielétrica (DBD), que é realizada em pressão atmosférica, envolvendo menores energias e a Implantação Iônica por Imersão em Plasma (3IP), que é realizada em baixa pressão, envolvendo energias mais elevadas. Após o tratamento, foi realizada a caracterização das amostras tratadas e não tratadas para efeito de comparação e também para verificar qual tratamento foi mais eficaz na obtenção de melhores propriedades físico-químicas da fibra para a obtenção dos compósitos termoplásticos, os quais foram produzidos pelo método de moldagem por compressão a quente. Várias técnicas de caracterização foram empregadas, tais como: microscopia eletrônica de varredura, microscopia de força atômica, espectroscopia Raman, espectroscopia de fotoelétrons excitados por raios X, difração de raios-X, e alguns ensaios mecânicos do compósito, tais como: testes de cisalhamento interlaminar e análise dinâmico-mecânica. Após a análise dos resultados, verificou-se que os tratamentos DBD e 3IP são ferramentas eficazes para melhorar a adesão da interface fibra/matriz polimérica, devido ao aumento da rugosidade da fibra e da introdução de grupos polares em sua superfície. Adicionalmente, houve um aumento da resistência ao cisalhamento dos compósitos obtidos a partir de fibras tratadas por ambos os processos a plasma (DBD e 3IP) / Abstract: In this it has been carried out the processing of thermoplastic composites obtained from carbon fibers (CF) treated by plasma assisted techniques. The employed treatments were Dielectric Barrier Discharge (DBD) that is performed in atmospheric pressure, involving low energy and Plasma Immersion Ion Implantation (PIII), which is held in low pressure regime, consisting of higher energies. After these treatments, both treated and untreated samples, were characterized. A comparison of the results was carried out to determine which treatment is most effective to achieve better physico-chemical properties on the fibers to obtain thermoplastic composites, which were produced by hot compression molding. Several characterization techniques were employed, such as scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction, and some mechanical tests of the composites, such as interlaminar shear strength (ILSS) and dynamic mechanical analysis (DMA). After analyzing the results, it was verified that the DBD and PIII treatments are effective tools for improving the adhesion of the carbon fiber/polymeric matrix interface, due to the CF roughness increasing and the introduction of polar groups on the carbon fiber surface. Additionally, it was noticed an increase of composites shear strength that were produced with treated carbon fibers (DBD and PIII) / Doutor
553

The effect of carriers on the flammability of polyester and triacetate

Streit, Nadine Joann January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
554

All-optical multi-access networks and fault manageable optical transport networks. / CUHK electronic theses & dissertations collection

January 1997 (has links)
by Chun-kit Chan. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (p. 143-158). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.
555

Spectroscopie multimodale et optimisation de multimatériaux / Multimodal spectroscopy and optimization of multimaterials

Chazot, Matthieu 29 November 2018 (has links)
Les composés multimatériaux à base de verre connaissent aujourd’hui un intérêt croissant, en particulier sous la forme de fibres optique pour des applications dans l’infrarouge. Parmi les matériaux vitreux qui existent, les verres chalcogénures présentent de nombreux avantages, tel qu’un large domaine de transparence allant du visible à l’infrarougeou encore de bonne aptitude à pouvoir être étirer. Pour réaliser de nouvelles fibres multimatériaux, il est important d’avoir accès à un choix étendu de compositions vitreuses étirables pouvant servir de matrice hôte. Il peut être montré que les verres actuellement utilisés pour la réalisation de fibres multimatériaux couvrent deux plages de température de transition vitreuse différentes ; soit à basse température (100-250 °C), ou à haute température (1000 °C et plus). Le manque d’information sur des verres étirables couvrant un domaine intermédiaire de température entre 250 et 1000 °C, nous ont conduit à explorer les propriétés et les capacités d’étirement des verres des deux systèmes ternaires Ge-S-I et Ga-As-S. Il sera montré que ces systèmes vitreux ont en effet des Tg permettant de couvrir cette gamme intermédiaire de température et ont de larges domaines de formation vitreux. Un ensemble de caractérisations physiques et thermiques sur les verres au sein des systèmes ternaires Ge-S-I et Ge-As-S seront présentés et analysés. Il sera possible d’observer, comment notamment les résultats des mesures thermomécaniques et de viscosité des échantillons synthétisés ont permis d’aborder dans les meilleures conditions les tests d’étirement des verres. Ou encore comment l’analyse minutieuse des propriétés a pu permettre de définir un domaine de composition combinant à la fois des propriétés optimales en termes de Tg et de transparence dans le visible, avec une bonne capacité à pouvoir être étirées sous forme de fibres optiques. Pour la première fois les domaines de fibrage des deux ternaires à partir de l’étirement d’une préforme seront présentés dans ce manuscrit. Ce travail présente également une caractérisation structurale des verres Ge-S-I. Cette étude a été réalisé en combinant la spectroscopie Raman, la spectroscopie IR et des calculs de chimie théorique afin de proposer un nouveau modèle structural basé sur les avancés les plus récentes d'une part sur la structure du système binaire Ge-S, puis ternaire Ge-S-I.Enfin, les résultats préliminaires sur la réalisation de fibres multimatériaux à partir de verres Ge-S-I et Ge-As-S pour la réalisation de sources laser entre 3 et 5 µm, seront présentés. Le projet, la méthodologie et les résultats quant à la réalisation d’une fibre multimatériaux à base de verre chalcogénure avec un cœur cristallisé de ZnS à partir de deux techniques innovantes différentes, seront présentés. / Nowadays, the interest on multimaterials based on glass matrix growth constantly, in particular in the field of multimaterial optical fibers for IR applications. Among the glass materials that exist, chalcogenide glasses presents a lot of advantages as for instance large transparency windows, spanning from the visible to the infrared or also good capability to be drawn. In the aim to realize new multimaterials fibers, it is important to get a large choice of draw able glass compositions that can be used as host matrix. It can be shown that the glass used currently to make multimaterial fibers covers two glass transition temperature range ; low temperature (100-250 °C) and high temperature (1000 °C and more). The lack of information regarding the existence of glass compositions that can be drawn into fibers at intermediate temperature (between 250 and 1000 °C), has lead us to explore the properties and the draw ability of glasses into two ternary systems: Ge-As-S and Ge-S-I. It will be presented that these glass systems possess Tg that covers this intermediate range of temperature and have large glass forming regions. Some physical and thermal characterizations of Ge-As-S and Ge-S-I glasses will be presented and analyzed. It will be possible to observe how the thermomechanical and viscosity measurements made on the different samples enabled us to perform the drawing tests in the best conditions. It will be also possible to see how a careful analysis of the Ge-S-I glass properties gave us the possibility to define a glass region combining optimal properties as Tg and transparency in the visible, and good capability to be drawn. For the first time, the fiber drawing region of both systems will be presented in this thesis. This work present also a structural characterization of Ge-S-I glasses using IR and Raman spectroscopy as well as DFT calculations, in the aim to propose a new structural model based on recent development in the Ge-S network structure. Finally, preliminary results on the realization of Ge-S-I and Ge-As-S based multimaterial fibers for the production of IR laser sources between 3 and 5 µm, will be presented. The last chapter will present the project, the methodology and the results obtained to realize multimaterial fibers with ZnS core, using two different technics.
556

Carbon fiber/vinylester composites in the marine environment: EIS as a means of determining an effective composite interface

Unknown Date (has links)
In this research, the degradation of carbon fiber/vinylester composites in marine environments was experimentally investigated. Additionally, two types of carbon fiber surface treatments, namely Polyhedral Oligomeric Silsesquioxane (POSS) and the industrial surface treatment F0E, were evaluated to determine their effectiveness in creating a fiber/matrix (F/M) interface for use in the marine environment. Electrochemical Impedance Spectroscopy (EIS) was explored as a new application of an existing technique for use in measuring the amount of water at the F/M interface in carbon fiber/vinylester composites. EIS spectra were used to determine equivalent electric circuit models that allow for the prediction of water at the interface. The location of water within the composite was determined through Positron Annihilation Lifetime Spectroscopy (PALS). Interlaminar shear strength and transverse tensile tests were carried out for dry conditions and after hygrothermal exposure of the composites to study the influence of the integrity of the F/M interface on the macroscopic response of the composite. / by Chris J. Vinci. / Thesis (M.S.C.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.
557

Pathogenic mechanisms of norepinephrine in cardiac injury in vitro. / 副腎上腺素在人工培養心臟纖維細胞的差別影響 / CUHK electronic theses & dissertations collection / Fu shen shang xian su zai ren gong pei yang xin zang xian wei xi bao de cha bie ying xiang

January 2008 (has links)
Background and objective. Cardiovascular disease (CVD) is the most important life-threatening disease. The heart is densely innervated with sympathetic fibers, however prolonged sympathetic activation can damage the heart, resulting in chronic heart failure. Recent findings suggest that norepinephrine (NE) may contribute to cardiac fibrosis and a loss of cardiomyocytes due to apoptosis. Many studies demonstrate that NE is able to induce transforming growth factor-beta (TGF-beta), connective tissue growth factor (CTGF) and vascular endothelial cell growth factor (VEGF), which are two key mediators during the cardiac remodeling process. Nowadays most of the studies in cardiac remodeling are focusing on myocytes, whereas a few studies have been paid to the role of the cardiac fibroblasts (CF). In this thesis, the role of NE in cardiac fibrosis and apoptosis was investigated in CF. The mechanisms by which NE induced TGF-beta, CTGF and VEGF expression in CF were examined. Furthermore, the therapeutic potentials in cardiac fibrosis by blocking NE with adrenergic receptor antagonists were explored. / Conclusions. NE is a pathogenic molecule involving cardiac remodeling. NE exhibited its fibrotic and apoptotic effects on CF in a concentration-dependent mariner. Up-regulation of the TGF-P/CTGF pathway could be a critical mechanism of NE-induced cardiac fibrosis, while NE was capable of activating Bax-Capase 3 to cause CF apoptosis. The presence of CTGF/VEGF complex in CF in response to NE may contribute to the inhibition of angiogenesis, which may be other mechanism of ischemic heart injury. These findings indicate that an increase in NE production associated with over activation of sympathetic system is harmful to the heart and may be a major cause of chronic heart failure. Furthermore, the ability of adrenergic receptor antagonists to block NE-induced cardiac fibrosis suggest the therapeutic approach by using NE receptor antagonists for patients with chronic heart diseases. / Methods and results. Rat CF was isolated, characterized, and stimulated with NF (0.01 to 100 muM for 6 to 72h). Procollagens (I and III), TGF-beta1, bax, bclXL, CTGF and VEGF gene expressions were measured by real-time PCR method. Collagen protein level was measured by Sirius red-based colorimetric method and Western blot. CTGF protein level, VEGF concentration, cell viability, apoptosis caspase 3 activity was measured by Western blot, ELISA, MTT assay cytometry, and flurogenic assay kit, respectively. Results showed that NE at concentrations of 0.01 to 0.1 muM was capable of up-regulating procollagens, TGF-beta1 and CTGF expression (ail p<0.05). However, NE at higher concentrations (10 to 100 muM) significantly induced CF apoptosis (p<0.01). This was demonstrated by a significant increase in bax gene expression and caspase-3 activity, while inhibiting bclXL gene expression. At this higher concentration of NE, CTGF expression was inhibited, whereas VEGF expression was promoted. However, using immunoprecipitation, the CTGF/VEGF complex was found in CF in response to NE, thereby inhibiting angiogenesis such as tube formation in cultured endothelial cells. Interestingly, addition of NE receptor antagonists produced differential effects on procollagen expression and apoptosis. For example, carvedilol and doxazosin, the alpha-receptor-associated non-selective antagonists, were able to inhibit NE-stimulated procollagens expression, but this was not inhibited by specific beta-receptor antagonists, metoprolol and propranolol, suggesting that NE signals through the alpha-receptor to mediate cardiac fibrosis. Interestingly, all four types of adrenoceptor antagonists had no effect on NE-induced CF apoptosis, which suggests that NE induces CF apoptosis via a receptor-independent mechanism. / Lai, Ka Bik. / Adviser: Yu Cheuk Man. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3419. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 160-199). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.
558

Ultrashort optical pulses from laser diode and erbium doped fibers.

January 1997 (has links)
Tong Yu Chung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references. / Abstract --- p.i / Acknowledgments --- p.ii / Table of Contents --- p.iii / Chapter (1) --- Introduction --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Overview of the Thesis --- p.2 / References --- p.4 / Chapter (2) --- Review of Ultrashort Pulse Generation and Pulsewidth Measurement --- p.5 / Chapter 2.1 --- Introduction --- p.5 / Chapter 2.2 --- Q-switching --- p.5 / Chapter 2.3 --- Gain-switching --- p.8 / Chapter 2.4 --- Mode-locking --- p.11 / Chapter 2.4.1 --- Active mode-locking --- p.12 / Chapter 2.4.2 --- Passive mode-locking --- p.13 / Chapter 2.5 --- Optical Pulse Compression --- p.15 / Chapter 2.6 --- Pulsewidth Detection Methods --- p.18 / Chapter 2.6.1 --- Streak camera --- p.18 / Chapter 2.6.2 --- Photodetector and sampling oscilloscope --- p.20 / Chapter 2.6.3 --- Nonlinear autocorrelator --- p.21 / Chapter 2.6.4 --- Other techniques --- p.24 / References --- p.25 / Chapter (3) --- Erbium Doped Fiber Amplifier and Active Mode-locking --- p.28 / Chapter 3.1 --- Introduction --- p.28 / Chapter 3.2 --- Erbium Doped Fiber Amplifier --- p.28 / Chapter 3.2.1 --- Background --- p.28 / Chapter 3.2.2 --- Experiment --- p.31 / Chapter 3.3 --- Additive Pulse Mode-locking --- p.35 / Chapter 3.4 --- Active Mode-locking --- p.37 / Chapter 3.4.1 --- Background --- p.37 / Chapter 3.4.2 --- Experiment and result --- p.38 / Chapter 3.4.3 --- Discussion --- p.43 / Chapter 3.5 --- Chapter Summary --- p.46 / References --- p.46 / Chapter (4) --- Passive Mode-locking of Erbium Doped Fiber Laser --- p.49 / Chapter 4.1 --- Introduction --- p.49 / Chapter 4.2 --- Background --- p.49 / Chapter 4.3 --- Experimental Setup --- p.51 / Chapter 4.4 --- Initialing Mode-locking --- p.54 / Chapter 4.5 --- Experimental Result --- p.55 / Chapter 4.5.1 --- Real time pulse train --- p.55 / Chapter 4.5.2 --- Autocorrelation trace --- p.57 / Chapter 4.5.3 --- RF spectrum --- p.58 / Chapter 4.5.4 --- Optical spectrum --- p.59 / Chapter 4.5.5 --- Time-bandwidth product --- p.60 / Chapter 4.5.6 --- Output power --- p.61 / Chapter 4.6 --- Discussion --- p.63 / Chapter 4.6.1 --- Linear pulse broadening --- p.63 / Chapter 4.6.2 --- Cavity oscillation --- p.65 / Chapter 4.6.3 --- Pump power hysteresis --- p.66 / Chapter 4.6.4 --- Sideband generation --- p.67 / Chapter 4.6.5 --- Spectral distortion --- p.68 / Chapter 4.7 --- Chapter Summary --- p.71 / References --- p.72 / Chapter (5) --- Application of Ultrashort Optical Pulses from Figure Eight Laser --- p.74 / Chapter 5.1 --- Introduction --- p.74 / Chapter 5.2 --- Dispersion Measurement --- p.74 / Chapter 5.2.1 --- Introduction --- p.74 / Chapter 5.2.2 --- Background --- p.75 / Chapter 5.2.3 --- Experiment and result --- p.76 / Chapter 5.2.4 --- Discussion and conclusion --- p.80 / Chapter 5.3 --- Time Domain Spectral Estimation --- p.82 / Chapter 5.3.1 --- Introduction --- p.82 / Chapter 5.3.2 --- Background --- p.82 / Chapter 5.3.3 --- Experiment and result --- p.83 / Chapter 5.3.4 --- Discussion --- p.88 / Chapter 5.4 --- Ultrashort Pulse Amplification --- p.89 / Chapter 5.4.1 --- Introduction --- p.89 / Chapter 5.4.2 --- Background --- p.89 / Chapter 5.4.3 --- Experiment and result --- p.92 / Chapter 5.4.4 --- Discussion and conclusion --- p.95 / References --- p.96 / Chapter (6) --- Picosecond Pulse Generation from Semiconductor Laser Diodes --- p.99 / Chapter 6.1 --- Introduction --- p.99 / Chapter 6.2 --- Gain-switching --- p.99 / Chapter 6.2.1 --- Experiment using commercial laser diodes --- p.99 / Chapter 6.2.2 --- Repetition rate multiplication --- p.102 / Chapter 6.2.3 --- Pulse compression with HDSF --- p.107 / Chapter 6.2.4 --- Fiber loop compressor --- p.110 / Chapter 6.3 --- Active or Hybrid Mode-locking --- p.112 / Chapter 6.3.1 --- Introduction --- p.112 / Chapter 6.3.2 --- Laser structure --- p.113 / Chapter 6.3.3 --- Experiment and result --- p.113 / Chapter 6.3.4 --- Discussion and conclusion --- p.116 / Chapter 6.4 --- Amplifier Modulation --- p.117 / Chapter 6.4.1 --- Introduction --- p.117 / Chapter 6.4.2 --- Experiment and result --- p.118 / Chapter 6.5 --- Wavelength Tuning --- p.120 / Chapter 6.5.1 --- Introduction --- p.120 / Chapter 6.5.2 --- Experiment and result --- p.121 / Chapter 6.5.3 --- Conclusion --- p.123 / Chapter 6.6 --- Chapter Summary --- p.124 / References --- p.124 / Chapter (7) --- Conclusion --- p.126 / Chapter 7.1 --- Summary of the Research --- p.126 / Chapter 7.1.1 --- Fiber lasers --- p.126 / Chapter 7.1.2 --- Diode lasers --- p.128 / Chapter 7.2 --- Further Study --- p.129 / Appendix I Project Instrumentation --- p.A-l / Appendix II Curve Fitting Program for the SHG Autocorrelation Trace --- p.A-8 / Appendix III Experiment Setup of Figure Eight Laser --- p.A-12 / "Appendix IV Curve Fitting Program for Determination of Second Order Dispersion, dD/dλ" --- p.A-14 / Appendix V 1.3 μm two sections DFB/TA Laser Diode Chips --- p.A-17 / Appendix VI Publication List --- p.A-l9
559

Caracterização da bainha fibrosa da palmeira Livistona chinensis para aplicação no design de produto

Jobim, Silvie Janis Mossate January 2018 (has links)
A palmeira Livistona chinensis, nativa do sul do Japão, é muito utilizada como planta ornamental em paisagismos em todo o território brasileiro, e além de adaptar-se bem a vários tipos de solos é de fácil reprodução. Essa palmeira produz uma bainha fibrosa na base de seu pecíolo, que é de fácil extração, plana, flexível e porosa, com características ainda pouco conhecidas e exploradas, é um material de fonte renovável que instiga a criatividade para seu uso tanto de forma artesanal quanto industrial. Neste contexto a caracterização da bainha fibrosa da palmeira Livistona chinensis se torna relevante, pois pode representar um leque de oportunidades para o desenvolvimento de novos produtos para o mercado. A caracterização da bainha fibrosa foi realizada com auxílio de microscópio eletrônico de varredura, espectrometria de energia dispersiva de raios-X, microtomografia, análise termogravimétrica, difração de raios-X, composição química e umidade, espectroscopia no infravermelho por transformada de Fourier Também foram obtidos valores para densidade, gramatura e resistência à tração, incluindo índice de absorção acústica, condutividade térmica e Termografia infravermelha. Os ensaios e análises realizados indicaram que a fibra possui propriedades e características que são comparáveis a outras fibras lignocelulósicas e os resultados estão bem próximas aos encontrados para as fibras de coco, como a composição química, densidade e índice de cristalinidade. Um dos fatores relevantes é o índice de condutividade térmica da bainha fibrosa que se manteve próximo aos valores de materiais isolantes utilizados industrialmente como a lã de rocha e lã de vidro. Quanto aos ensaios de termografia de infravermelho, que apontam seu potencial para ser usado como isolante térmico. / The Livistona chinensis palm, native to southern Japan, is widely used as an ornamental plant in landscaping throughout the Brazilian territory, and besides adapting well to various types of soils, it is easy to reproduce. It produces a fibrous sheath at the base of its petiole, which is easy to extract, flat, flexible and porous, with characteristics still little known and exploited, is a renewable source material, and which instigates creativity for its use both artisanly and industrial. In this context the characterization of the fibrous sheath of palmeira Livistona chinensis becomes relevant, since it can represent a range of opportunities for the development of new products for the market. The characterization of the fibrous sheath was performed with scanning electron microscope, X-ray dispersive energy spectrometry, microtomography, thermogravimetric analysis, X-ray diffraction, chemical composition and humidity, Fourier transform infrared spectroscopy We also obtained values for density, weight and tensile strength, including acoustic absorption index, thermal conductivity and infrared thermography. The tests and analyzes indicated that the fiber has properties and characteristics that are comparable to other lignocellulosic fibers and the results are very close to those found for coconut fibers, such as chemical composition, density and crystallinity index. One of the relevant factors is the thermal conductivity index of the fibrous sheath that remained close to the values of insulating materials used industrially as rock wool and glass wool. Regarding the infrared thermography tests, which point out its potential to be used as thermal insulation.
560

Preparação e caracterização de nanocompósitos de polipropileno reforçados com argila verde lodo e fibra da castanha-do-brasil. / Preparation and characterization of polypropylene nanocomposites reinforced with organophilic clay and brazilian nut fibers.

Gomes, Leila Veronica da Rocha 17 December 2015 (has links)
A incorporação de nanocargas minerais e vegetais em matriz polimérica tem sido estudada, principalmente, com o objetivo de melhorar as propriedades de desempenho mecânico dos polímeros para aplicações industriais diversas. As argilas organofilizadas e as fibras vegetais estão entre os materiais que se destacam como cargas adicionadas ao polímero para a formação de nanocompósitos. Essa área de estudo tem despertado interesse também devido à obtenção de melhorias de propriedades físicas, químicas e mecânicas desses materiais quando comparadas às dos materiais compósitos tradicionais. O objetivo da pesquisa foi estudar algumas dessas propriedades em nanocompósitos produzidos com polipropileno, argila esmectítica brasileira e fibra do ouriço da castanha-do-brasil, com ênfase na melhora das propriedades mecânicas. Inicialmente, os materiais componentes foram caracterizados por diversos ensaios, tais como, difração de raios X, granulometria, infravermelho, microscopia eletrônica de varredura, temperatura de degradação térmica, além de ensaios específicos para medir características individuais da argila, como, viscosidade Fann, inchamento de Foster, limite de plasticidade, fluorescência de raios X, entre outros. Posteriormente, o polipropileno graftizado com anidrido maleico (PP-g-MA) foi incorporado ao PP puro (PP), em extrusora dupla rosca, nas proporções de 5%, 10% e 20% em peso e injetados os corpos de prova para os ensaios de tração e impacto. A partir dos resultados das propriedades mecânicas definiu-se o uso de 5% de PP-g-MA para preparação dos nanocompósitos definitivos. Finalmente, variou-se a quantidade de fibra na composição. Foram obtidos nanocompósitos de polipropileno (PP) e 5% PPg- MA reforçado com 5% em peso da argila organofilizada e fibra do ouriço da castanha-do-brasil em três proporções 5%, 10% e 15% em peso. As amostras foram caracterizadas por diferentes técnicas (DRX, MEV, FTIR, TG/DSC) e medidas as resistências mecânicas à tração, flexão e impacto. Todos os nanocompósitos apresentaram aumento na resistência mecânica quando comparados ao polímero sem argila e fibra. / The incorporation of vegetable and mineral nanofillers in polymer matrix has been studied mainly in order to improve the mechanical performance properties of polymers for various industrial applications. The organoclays and vegetable fibers are among the materials that stand out as fillers added to polymer for the formation of nanocomposites. This study has also attracted interest owing to achieve improvements in various properties when compared to other traditional composite materials. This study aims to investigate the effects of adding organophilic clay and brazilian nut fibers on the some physical, chemical and mechanical properties of polypropylene nanocomposite. Initially, The component materials were characterized by tests, such as X-ray diffraction, particle size, infrared, scanning electron microscopy, thermal degradation, as well as specific assays for measuring individual characteristics and properties of the clay, for example, viscosity Fann, Foster swelling, plasticity limit, X-ray fluorescence, among others. In the second step, the graftizado polypropylene with maleic anhydride (PP-g-MA) was incorporated into the pure PP, extruded in proportions of 5 weight%, 10 weight% and 20 weight% and injected the samples for tensile and impact tests. From the results of mechanical properties was defined using 5 weight% of PP-g-Ma for the incorporation into pure PP. Finally, samples were prepared containing only polymer, graftizado polymer/clay, graftizado polymer/clay/ fiber. The addition of clay was 5 weight% and the fiber was added to 5 weight%, 10 weight% and 15% by weight, respectively. The nanocomposites were prepared double-screw extruder and the samples injection molded, then, they were characterized by X-ray diffraction, scanning electron microscope (SEM), thermal analysis (TG/DSC), infrared spectroscopy and mechanical strength, flexural and impact test. All the nanocomposites increased mechanical properties as compared to polymer without clay and fibers.

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