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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.
451

Wire bond failure Mechanism and microstructure analysis

Jang, Herng-Shuoh 01 July 2002 (has links)
The Au-Al bond is a commonly used interconection in IC package.The different composition for Au wire will change the different IMC growth. In this study, we will discuss the pure Au wire, and little Pd or Cu addition in Au wire reacted with Al pad for thermal aging, and we will give the models for these cases.
452

Coking Characteristics on Cu/Ni Catalysts

Tzeng, Li-De 26 June 2003 (has links)
none
453

Defect Engineering

Steinegger, Thomas 10 July 2009 (has links) (PDF)
Die Kenntnisse über die zur Passivierung führenden Wechselwirkungen des Verunreinigungselements Cu mit EL2 und EL6 wurden dahingehend erweitert, dass ein Gültigkeitsbereich für die Messungen zur Bestimmung der konzentrationsproportionalen Messgröße der Defekte festgelegt wurde. Der Defekt EL6 ist das die 0.8 eV-PL-Emission bedingende und die Ladungsträgerlebensdauer determinierende Rekombinationszentrum. Die Lebensdauer wird durch mindestens ein weiteres Zentrum beeinflusst. Die atomare Struktur des EL6 wurde mit AsGa VAs und die des weiteren Zentrums mit Asi bestimmt. Mittels Wärmebehandlung kann die Ladungsträgerlebensdauer gezielt beeinflusst werden. Bei der Bildung und Annihilation sowie der Verteilung der Defekte EL2, EL6, VGa und der As-Ausscheidungen besteht eine wechselseitige Korrelation. Sowohl strukturelle Defekte als auch die Inkorporation von Dotierelementen, deren Atomradien deutlich kleiner sind als Ga und As, stellen beeinflussende Faktoren dar. Das Defekt-Transformations-Modell erklärt die Bildung wachstumsfähiger Keime einer As-Ausscheidung durch EL2 bzw. EL6 mit den sich in der ersten Koordingationssphäre befindenden As-Atomen. Das Gitterrelaxations-Modell ermöglicht die Interpretation der katalytischen Wirkung des Dotierelements C. Die Umsetzung dieser Ergebnisse bedeutet die Anwendung des Defect Engineerings im SI-LEC-GaAs.
454

Metal release from powder particles in synthetic biological media

Midander, Klara January 2006 (has links)
<p>Humans are exposed to metals and metal-containing materials daily, either conscious, e.g. using metal tools or objects, or unconscious, e.g. during exposure to airborne metal-, and metal-containing particles. The diffuse dispersion of metals from different sources in the society, and the concern related to its potential risk for adverse effects on humans have gained an increased public and governmental attention both on a national and international level. In this context, the knowledge on metal release from metallic objects or metal-containing particles is essential for health risk assessment.</p><p>This thesis focuses on the study of metal release from powder particles of stainless steel and Cu-based materials exposed to synthetic body fluids mainly for simulating lung-like environments. The study comprises: i) development of a suitable experimental method for metal release studies of micron sized particles, ii) metal release data of individual alloy constituents from stainless steel powder particles of different particle sizes, and iii) Cu release from different Cu-based powder particles. In addition, the influence of chemical and physical properties of metallic particles and the test media are investigated. Selected results from Ni powder particles exposed to artificial sweat are presented for comparison. The outcome of this research is summarized through ten questions that are formulated to improve the general understanding of corrosion-induced metal release from metallic particles from a health risk perspective.</p><p>A robust, reproducible, fairly simple, and straightforward experimental procedure was elaborated for metal release studies on particles of micron or submicron size. Results in terms of metal release rates show, for stainless steel powder particles, generally very low metal release rates due to a protective surface oxide film, and Fe preferentially released compared to Cr and Ni. Metal release rates are time-dependent for both stainless steel powder particles and the different Cu-containing powders investigated. The release of Cu from the Cu-containing particles depends on the chemical and compositional properties of the Cu-based material, being either corrosion-induced or chemically dissolved. Moreover, the test medium also influences the metal release process. The metal release rate increases generally with decreasing pH of the test media. However, even at a comparable pH, the release rate may be different due to differences in the interaction between the particle surface and specific media.</p><p>The nature of particles is essentially different compared to massive sheet in terms of physical shape, surface composition and morphology. The surface area, and even the surface composition of metallic particles, depend on the particle size. The specific surface area of particles, area per mass, is intimately related to the particle size and has a large effect on the metal release process. Release rates increase with decreasing particle size due to a larger active surface area that takes part in the corrosion/dissolution process. The surface area that actually is active in the corrosion and metal release process (the effective area) governs the metal release process for both particles and massive sheet of metals or alloys. For particles, the effective surface area depends also on agglomeration conditions of particles during exposure.</p>
455

7 - 8 klasių mokinių kūno kultūros žinių įgyjimo ir fizinio aktyvumo skatinimas aktyvinamaisiais mokymosi metodais / Activating teaching methods and their effect on the physical activity of the knowledge of healthy way of life among 7 - 8 form student in a basic school

Balevičiūtė, Rūta 30 May 2005 (has links)
According to the scientific research schoolchildren lack knowledge of healthy way of life and physical education. Most researchers claim that students health is getting worse and physical inactivity, smoking. Irrational nutrition has been spreading. However, school physical education research is mostly based on the development of schoolchildren physical abilities of various body systems. Thees the experiment was carried out to investigate the incorporation of theoretical lessons on physical education and healthy way of life into the process of physical training by using using different activating methods. Research objective: To investigate the efficiency of activating teachings methods and their effect on the physical activity and acquistition of the knowledge oh healthy way of life among 7 -8 fom students in a basic school. 386 schoolchildren participated in the pedagogical experiment conducted in Vilnius „Emilijos Pliaterytės” basic school from September 2004 till March 2005. Research methods used in a Masters thesis were as follows: analysis of literature, questionnaire methods, pedagogical experiment, mathematical, statistical analysis. The change in the knowledge of the healthy way of life and physical educations was determined by a questionnaire method during the period of experiment. Activating methods (discussions, debates, brainstorming, each student active invillvement) were used in experimental gruops to extend and improve students knowledgw of healthy... [to full text]
456

Développement d'un modèle d'efforts de coupe multi-opérations et multi-matériaux. Application au tournage du cuivre pur dans différents états métallurgiques.

Campocasso, Sébastien 29 November 2013 (has links) (PDF)
La modélisation des efforts de coupe en usinage est nécessaire pour prédire certaines caractéristiques de la pièce usinée comme sa géométrie, son état de surface ou encore l'intégrité de la matière en sub-surface.Les nombreux modèles d'efforts de coupe déjà développés sont souvent appliqués dans le cas d'opérations d'usinage simples, ce qui limite leur diffusion vers le milieu industriel, alors qu'il existe un réel besoin de modélisation d'opérations d'usinage complexes et variées, et prenant en compte d'éventuels changements métallurgiques au niveau du matériau usiné.L'objectif de ces travaux est de proposer un modèle d'efforts de coupe appliqué à toute opération de tournage d'une part et considérant certaines propriétés mécaniques du matériau usiné d'autre part.Concernant l'aspect multi-opérations, un modèle géométrique utilisant des transformations homogènes a été développé et permet de décrire à la fois la trajectoire et la géométrie de l'outil. Les effets de paramètres originaux, tels que le diamètre de la pièce, l'angle de direction d'arête et le rayon de bec, sont étudiés, notamment à l'aide de nouvelles configurations de coupe élémentaires. La prise en compte de ces paramètres dans les relations de coupe locales permet finalement d'améliorer la simulation des efforts de coupe lors d'un contournage.L'approche utilisée pour l'aspect multi-matériaux consiste à modifier progressivement le matériau usiné. Ainsi, le matériau initial, le cuivre pur, a été étudié dans différents états métallurgiques, obtenus par des traitements thermo-mécaniques. En particulier, le procédé d'extrusion coudée à aires égales (ECAE) a été utilisé afin d'écrouir le matériau dans la masse. Ainsi, trois matériaux aux caractéristiques mécaniques différentes mais conservant plusieurs caractéristiques communes (thermiques notamment) ont pu être comparés en termes d'efforts de coupe. Les coefficients des relations de coupe sont finalement mis en regard des propriétés mécaniques obtenues par des essais de traction et de compression à grande vitesse.
457

Characterization of High-PGE Low-Sulphur Mineralization at the Marathon PGE-Cu Deposit, Ontario

Ruthart, Ryan January 2013 (has links)
The Marathon PGM-Cu deposit is hosted by the Coldwell alkaline complex, which consists predominantly of gabbro and syenite and was emplaced at 1108 Ma as part of the Mid-Continent Rift System. Mineralization at the Marathon PGM-Cu deposit is hosted by the Two Duck Lake Gabbro (TDLG), a fresh olivine-bearing gabbro. The Marathon deposit contains several zones of mineralization including the Basal Zone, the Main Zone and the W-Horizon. The W-Horizon is a high-grade PGE zone characterized by low S, low Cu/Pd and high Cu/Ni. The sulphide mineral assemblage is predominantly chalcopyrite and bornite. This contrasts with the Main Zone where the dominant sulphide mineral assemblage is chalcopyrite and pyrrhotite. The Main Zone contains higher S, higher Cu/Pd and shows a decrease in Cu/Pd and pyrrhotite/chalcopyrite from base to top. Four drill holes were selected for detailed analysis to characterize the W-Horizon style of mineralization. Detailed petrographic study of the pristine and largely unaltered TDLG shows that wide spread hydrothermal alteration is not responsible for the mineralization. Detailed outcrop mapping shows that the TDLG intruded as a series of multiple intrusions in a dynamic magmatic system. Geochemical studies through the W-Horizon show that the mineralization is not the result of crystallization in a layered intrusion. The results of geochemical assays and electron microprobe analysis of olivine grains show that the chemistry through the TDLG hosting the W-Horizon is erratic. This data supports the TDLG intruding as a series of sills in a dynamic conduit environment. The calculated sulphide metal tenors for the W-Horizon are higher than can be explained by closed system R Factor models. Multistage dissolution upgrading in an open system is examined as the process forming the W-Horizon. This model is able to produce the sulphide metal tenors observed in the W-Horizon. Sulphur loss also affects grades and tenors and was examined through geochemical and petrological data. The change in sulphide mineral assemblage from a pyrrhotite and chalcopyrite (S-rich) to chalcopyrite and bornite (S-poor) supports S-loss. Whole rock S and Se contents are also analyzed to investigate S loss, a lower S/Se indicates that sulphur has been removed from the system. Average S/Se values are ~800 for the W-Horizon, ~1980 for the Main Zone and ~1700 in unmineralized samples. The very low S/Se observed within the W-Horizon supports S-loss. Sulphur loss in a dynamic magmatic conduit system is proposed for the formation of the W-Horizon mineralization. In this model sulphur undersaturated basaltic magma interacted with an immiscible sulphide liquid in a magma conduit, resulting in the dissolution of sulphide into the basaltic melt and PGE enrichment.
458

Catalisadores Cu-, Co- ou Fe-ZSM-5 caracterização e avaliação na redução de NO a N2 com hidrocarbonetos na presença ou ausência de vapor de água.

Fernandes, Juliana Esteves 04 March 2005 (has links)
Made available in DSpace on 2016-06-02T19:56:55Z (GMT). No. of bitstreams: 1 DissJEF.pdf: 1826030 bytes, checksum: a3043074648b14bbec76bd05d3190200 (MD5) Previous issue date: 2005-03-04 / Universidade Federal de Sao Carlos / The minimization of the emissions of nitrogen oxides (NOx) in the atmosphere has been one of the great goals in the area of environmental protection. Among the possible processes to treat the NOx, the selective catalytic reduction of NO with hydrocarbons (SCR-HC) has presented important expectations. For this process, the metal/ZSM-5 type catalysts have appropriate levels of conversion in oxidative conditions. In this context, the aim of this work was to prepare Cu, Co and FeZSM-5 catalysts. The samples were characterized by XRD, DRS-UVVIS, FTIR, H2-TPR, SEM and tested in the reduction of NO to N2 with propane or methane in oxidative atmosphere in the presence or absence of water steam. The H2-TPR data showed that the cationic species present in the prepared Cu, Co and FeZSM-5 catalysts, after thermal activation, were mainly Cu2+ (Cu&#945; 2+ e Cu&#946; 2+), Co2+ and Fe3+ cations located in charge compensation sites in the zeolite, respectively. From FTIR and DRS-UVVIS it was also possible identify oxide species, which were present in a lower content. In the reduction of NO to N2 in the absence of water steam, the CuZSM-5 catalysts showed higher levels of conversion of NO than those based in Co and Fe. However, the FeZSM-5 catalysts showed, in this condition, activity at lower temperatures. This behavior makes them potentially interesting to be applied for practical purposes. On the other hand, in the presence of water steam, it was verified a higher loss of activity of the CuZSM-5 catalyst, which was totally restored removing the water in the feed. For the Co and FeZSM-5 catalysts, the activity loss in the presence of water steam was partially recovered during time on stream. / A minimização das emissões de óxidos de nitrogênio (NOx) na atmosfera tem sido um dos grandes desafios da área de proteção ambiental. Dentre os processos para o tratamento dos NOx possíveis, a redução catalítica seletiva do NO com hidrocarbonetos (RCS-HC) vem apresentando excelentes perspectivas. Para este processo os catalisadores metal/zeólita ZSM-5 possuem adequados níveis de conversão em condições oxidantes. Dentro deste contexto, este trabalho teve como objetivo preparar catalisadores Cu, Co e FeZSM-5. As amostras foram caracterizadas por DRX, DRS-UVVIS, FTIR, RTP-H2, MEV e sua atividade verificada através da redução de NO a N2 com propano ou metano em atmosfera oxidante, na presença ou ausência de vapor de água. Os resultados de RTP-H2 mostraram que as espécies presentes nos catalisadores Cu, Co e FeZSM-5, após ativação térmica, foram principalmente os cátions Cu2+ (Cu&#945; 2+ e Cu&#946; 2+), Co2+ e Fe3+ compensando carga na zeólita, respectivamente. A partir de FTIR e DRS-UVVIS foi possível, também, identificar espécies oxidas, as quais estavam presentes em teores menores. Na redução de NO a N2 na ausência de vapor de água os catalisadores CuZSM-5 apresentaram maiores conversões de NO que os contendo Fe ou Co. Entretanto, os catalisadores FeZSM-5 apresentaram, nessa condição, atividade em temperaturas menores, o que mostra uma vantagem para o seu uso prático. Na presença de vapor de água, verificou-se uma maior queda da atividade no catalisador CuZSM-5, somente recuperada com a retirada desse composto na alimentação, sendo que para os catalisadores CoZSM-5 e FeZSM-5 a perda de atividade foi parcialmente recuperada ao longo do tempo.
459

Correlações entre parâmetros microestruturais, parâmetros térmicos e resistência mecânica de ligas Sn- Bi e Sn-Bi-(Cu,Ag) / Correlations among microstructures, thermal parameters and mechanical resistances of sn-bi-(cu,ag) alloys

Silva, Bismarck Luiz 07 October 2016 (has links)
Submitted by Izabel Franco (izabel-franco@ufscar.br) on 2016-10-26T17:47:35Z No. of bitstreams: 1 TeseBLS.pdf: 15809941 bytes, checksum: e94eb4f0e858901ec9568dacd81ecf51 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-11-08T18:28:27Z (GMT) No. of bitstreams: 1 TeseBLS.pdf: 15809941 bytes, checksum: e94eb4f0e858901ec9568dacd81ecf51 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-11-08T18:28:33Z (GMT) No. of bitstreams: 1 TeseBLS.pdf: 15809941 bytes, checksum: e94eb4f0e858901ec9568dacd81ecf51 (MD5) / Made available in DSpace on 2016-11-08T18:28:40Z (GMT). No. of bitstreams: 1 TeseBLS.pdf: 15809941 bytes, checksum: e94eb4f0e858901ec9568dacd81ecf51 (MD5) Previous issue date: 2016-10-07 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / The present research aims to develop a theoretical/experimental analysis of the combined effects of solidification thermal parameters, Bi content and addition of ternary elements (Cu, Ag) on the final microstructure aspects and on the final mechanical resistances of directionally solidified Sn-Bi, Sn-Bi-Ag and Sn-Bi-Cu solder alloys under transient heat flow conditions. Hence, experimental interrelations between microstructure and thermal parameters and between mechanical properties and microstructure could be established. The microstructures regarding the Sn-34wt.%Bi and Sn-52wt.%Bi alloys show the presence of β-Sn dendrites with Bi precipitates on their own, being enveloped by a lamellar binary Sn-Bi eutectic. The Sn-58wt.%Bi eutectic alloy show a variety of microstructures along the length of the directionally solidified casting, which includes binary eutectic, Bi plates, Bi trifoils and fishbone eutectic. In the case of the ternary Sn-Bi-Ag and Sn-Bi-Cu chemistries, microstructures are constituted by β-Sn dendrites decorated with Bi particles, Bi-Sn eutectic and Cu6Sn5 and Ag3Sn intermetallic particles for the Cu and the Ag bearing alloys, respectively. Experimental growth laws have been derived for both dendritic (λ1, λ2, λ3) and eutectic (λfine, λcoarse) arrangements considering the following alloys: binary Sn-34wt.%Bi, Sn-52wt.%Bi e Sn-58wt.%Bi alloys and ternary Sn- 34wt.%Bi-0.1wt.%Cu, Sn-34wt.%Bi-0.7wt.%Cu e Sn-33wt.%Bi-2wt.%Ag. Considering the binary Sn-Bi, it has been observed that increasing Bi content (34wt.%-->52wt.%-->58wt.%Bi), may cause a decrease on both strength and ductility, except for the sample at P=6mm of the Sn-52wt%Bi alloy. Hall-Petch type functional correlations have been able to represent the evolution of the tensile mechanical properties for the examined Sn-Bi and Sn-Bi-X alloys. / A presente proposta objetiva desenvolver uma análise teórico/experimental sobre os efeitos combinados dos parâmetros térmicos de solidificação (velocidade de solidificação VL e taxa de resfriamento, ṪL), do teor de Bi e das adições de terceiros elementos (Cu, Ag) na microestrutura e na resistência mecânica de ligas Sn-Bi, Sn-Bi-Ag e Sn-Bi-Cu solidificadas unidirecionalmente, estabelecendo correlações experimentais do tipo microestrutura/parâmetros térmicos e microestrutura/propriedades mecânicas. As microestruturas para as ligas binárias Sn-34%Bi e Sn-52%Bi são constituídas de dendritas de Sn com precipitados de Bi em seu interior, circundadas por um eutético lamelar binário, Sn-Bi. A liga eutética Sn-58%Bi mostrou uma ampla gama de microestruturas ao longo de todo o lingote, englobando o eutético binário Sn-Bi, placas e trifoils de Bi e eutético fishbone. Quanto às ligas ternárias Sn-Bi-Cu e Sn-Bi-Ag observa-se que as microestruturas são constituídas de dendritas β-Sn “decoradas” com partículas de Bi em seu interior, circundadas por uma mistura eutética irregular (Bi+Sn) e seus respectivos compostos intermetálicos primários Cu6Sn5 e Ag3Sn, respectivamente. As leis de crescimento experimentais dendrítico (λ1, λ2, λ3) e eutético (λfino, λgrosseiro) para as ligas binárias Sn-34%Bi, Sn-52%Bi e Sn-58%Bi e para as ligas ternárias Sn-34%Bi- 0,1%Cu, Sn-34%Bi-0,7%Cu e Sn-33%Bi-2%Ag em função de V e Ṫ foram caracterizadas por equações na forma de potência com aplicação de expoentes típicos. No caso das ligas binárias Sn-Bi, foi observado que com o aumento do teor de Bi (34%-->52%-->58%Bi), tanto o limite de resistência à tração (σt) quanto o alongamento específico diminuem, com exceção dos resultados para a amostra P=6mm da liga Sn-52%Bi. Relações funcionais do tipo Hall-Petch foram capazes de descrever a variação das propriedades mecânicas de tração de ligas Sn-Bi e Sn-Bi-X.
460

Estudos de biopolímeros a base de quitina e quitosana quimicamente transformados para quelação de metais e para a captura e fixação de dióxido de carbono / Study of chitin and chitosan biopolymers chemically modified for metal chelation and for capture and fixation of carbon dioxide

Pereira, Fernanda Stuani [UNESP] 09 June 2016 (has links)
Submitted by Fernanda Stuani Pereira null (ferstuani@hotmail.com) on 2016-06-22T22:22:49Z No. of bitstreams: 1 Tese-FERNANDA STUANI PEREIRA.pdf: 6105856 bytes, checksum: 653cf59956934017da496664aa74e886 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-06-24T17:11:14Z (GMT) No. of bitstreams: 1 pereira_fs_dr_prud.pdf: 6105856 bytes, checksum: 653cf59956934017da496664aa74e886 (MD5) / Made available in DSpace on 2016-06-24T17:11:14Z (GMT). No. of bitstreams: 1 pereira_fs_dr_prud.pdf: 6105856 bytes, checksum: 653cf59956934017da496664aa74e886 (MD5) Previous issue date: 2016-06-09 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O presente trabalho descreve modificações estruturais feitas na cadeia lateral do polímero quitosana mediante a N-alquilação com diferentes aldeídos aromáticos, a qual originam bases de Schiff como produtos intermediários, seguido de uma redução com cianoborohidreto de sódio (NaBH3CN). Subsequentemente, reações de acoplamento entre o produto sintetizado N-benzil quitosana e diferentes sais de diazônio foram realizadas para produzir uma nova classe de compostos poli-azóicos a partir deste polímero. Diferentes materiais foram sintetizados para investigar a influencia de diferentes substituintes na complexação de metais e futuros estudos de eficiência biológica. Pela técnica de ressonância magnética nuclear de próton em solução, o grau de substituição dos poli-azo-compostos foi de 46 a 66%. Os compostos foram caracterizados por FT-IR e RMN de 13C no estado sólido e RMN de 15N em solução, que confirmaram a síntese dos derivados poliméricos. Também foi realizado um estudo da interação destes materiais sintetizados com os íons metálicos Cu(II) e Zn(II). Para a caracterização dos complexos, utilizou-se as técnicas de titulação complexométrica, FAAS, MEV, EDS, difratometria de raios X, EPR e TG/DTG. Por titulação complexométrica e FAAS, a quitosana pura mostrou maior capacidade em complexar/adsorver os metais do que seus derivados. A capacidade de adsorver íons Cu(II) foi maior do que íons Zn(II) para todos os compostos. Por MEV e EDS, observou-se que além do cobre coordenado pelos sítios reativos dos materiais, o sal sulfato de cobre foi adsorvido pela superfície polimérica dos mesmos. Assim, foram realizadas reações de complexação utilizando o sal CuCl2.2H2O e os resultados mostraram que esse comportamento não ocorre para este sal. Para os complexos utilizando o sal sulfato de zinco, praticamente não se observa o sal adsorvido na superfície polimérica, devido à baixa capacidade de complexação por esse metal. A difratometria de raios X mostrou uma redução da cristalinidade dos complexos de cobre e zinco formados pela quitosana e o derivado Q1Benzil devido a maior capacidade desses materiais em quelar íons metálicos. Para os complexos de Cu(II) e Zn(II) formados a partir do composto Azo-Anisidina, o índice de cristalinidade aumenta, o que pode estar associado a formação de diferentes ligações de coordenação nesse composto. A formação dos complexos também foi confirmada por espectroscopia Raman. Os espectros de EPR dos complexos de Cu(II) formados a partir do sal CuCl2.2H2O mostram a presença de uma estrutura hiperfina bem resolvida, da mesma forma que foi observado para o complexo Quitosana-CuSO4, na qual a grande maioria dos centros de cobre são monoméricos e provavelmente ligados aos polímeros. As curvas de TG/DTG mostraram que os derivados poliméricos degradam a temperaturas menores que o polímero não modificado, e os complexos com sulfato de cobre apresentaram perfis TG/DTG diferentes dos complexos sintetizados a partir do sal cloreto de cobre. Por fim, tanto a quitosana quanto seus derivados Q1Benzil, Q2Benzil e Q2Benzil utilizando a quitosana de baixo peso molecular se mostraram efetivos na síntese de carbonatos através da captura e fixação de CO2 por estes materiais poliméricos. / The present work describes structural modifications in the side chain of the polymer chitosan by N-alkylation with different aromatic aldehydes, which originates Schiff base as an intermediate, followed by reduction with sodium cyanoborohydride (NaBH3CN). Subsequently, coupling reactions between the synthesized product N-benzyl chitosan and various diazonium salts were carried out to produce a new class of poly-azo compounds from this polymer. Different materials were synthesized to investigate the influence of different substituents on metal chelation and future studies of their biological efficience. From nuclear magnetic resonance technique, the degree of substitution of the poly-azo compounds was between 46 and 66%. The compounds were characterized by FT-IR, 13C NMR in solid state and 15N NMR in solution, which confirmed the synthesis of the polymeric derivatives. The interaction of the synthesized materials with the metal ions Cu(II) and Zn(II) was also studied. For the characterization of such metal complexes, the techniques complexometric titration, FAAS, SEM, EDS, X-ray diffraction, EPR and TG/DTG were employed in this work. By complexometric titration and FAAS, pure chitosan showed greater capacity for complex/adsorb metals than its derivatives. The capacity of adsorbing Cu(II) ions was greater than Zn(II) ions for all compounds. The synthesized complexes were studied by various spectroscopic techniques. By SEM and EDS, it was observed that in addition of copper coordination, copper sulphate salt was adsorbed by the polymer surface. Thus, complexation reactions were carried out using the salt CuCl2.2H2O and the results showed that this behavior does not occur for this salt. For complexes using zinc sulfate salt, hardly observes this salt adsorbed on the polymeric surface due to the low capacity for complexing this metal. The X-ray diffraction showed a reduction of the crystallinity of copper and zinc complexes formed by chitosan and Q1Benzil derivative due to the greater ability of these materials to chelate metal ions. For the complexes of Cu(II) and Zn(II) formed from Azo-Anisidine compound, the crystallinity index increases, which can be associated with formation of different coordination bonds with the compound. The formation of the complex was also confirmed by Raman spectroscopy. EPR spectra of Cu(II) formed from the CuCl2.2H2O salt showed the presence of well resolved hyperfine structure in the same way as it was observed for chitosan-CuSO4, in which the majority of copper centers are monomeric and probably bound to the polymer. The TG/DTG curves showed that polymeric derivatives are less stable than the unmodified polymer, and complexes with copper sulfate had TG/DTG curves different from the complexes synthesized from copper chloride salt. Finally, chitosan and the derivatives Q1Benzil , Q2Benzil and Q2Benzil from low molecular weight chitosan were effective in the synthesis of carbonates through the capture and sequestration of CO2 by these polymeric materials. / FAPESP: 2012/13901-3

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