No description available.

Thesis (M.E.S.)--The Evergreen State College, 2007. / Title from title screen viewed (2/14/2008). Includes bibliographical references (leaves 34-40).

Thesis (MSc.(Chemistry))--University of Pretoria, 2008. / Includes bibliographical references.

Submitted by Juliana Bovi de Oliveira null (juliana_bovi@hotmail.com) on 2016-04-28T03:07:28Z No. of bitstreams: 1 Dissertação de Mestrado - Juliana B Oliveira.pdf: 3628116 bytes, checksum: 38a7295f033a2a9bda4b4118db7acee0 (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-05-02T11:57:44Z (GMT) No. of bitstreams: 1 oliveira_jb_me_guara.pdf: 3628116 bytes, checksum: 38a7295f033a2a9bda4b4118db7acee0 (MD5) / Made available in DSpace on 2016-05-02T11:57:44Z (GMT). No. of bitstreams: 1 oliveira_jb_me_guara.pdf: 3628116 bytes, checksum: 38a7295f033a2a9bda4b4118db7acee0 (MD5) Previous issue date: 2016-03-08 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Nos últimos anos, reforços constituídos de nanoestruturas em carbono, tais como nanotubos de carbono, fulerenos, grafenos e nanofibras de carbono, vêm sendo muito pesquisados devido às suas elevadas propriedades mecânicas, elétricas e térmicas. Uma vez que, as nanofibras de carbono consistem em um reforço contínuo (ou na forma de mantas) de elevada área superficial específica, associado ao fato de que estas podem ser obtidas a um baixo custo e em grandes quantidades, estas vêm se mostrando vantajosas quando comparadas aos tradicionais nanotubos de carbono. Assim, as nanofibras de carbono são ótimas candidatas para a obtenção de materiais avançados, podendo estas serem utilizadas como reforços em compósitos com diversas aplicações, tais como em implantes neurológicos e ortopédicos, como suportes de catalisadores, artefatos para aplicações aeroespaciais, dentre outras. Desta forma, o objetivo principal deste trabalho é a produção de nanofibras de carbono, empregando como precursora a manta de poliacrilonitrila (PAN) obtida pelo processo de eletrofiação via solução polimérica, com posterior utilização como reforço em compósitos poliméricos. Neste trabalho, uma manta de poliacrilonitrila com nanofibras de diâmetro de aproximadamente (375 ± 85) nm foi obtida por eletrofiação, sendo esta posteriormente carbonizada. A massa residual resultante do processo de carbonização foi de aproximadamente 38% em massa, com uma redução de 50% nos diâmetros das nanofibras após a queima das mantas de PAN, sendo que as mesmas apresentaram um rendimento de 25%. Na análise da estrutura cristalina do material carbonizado, verificou-se que o material apresentou uma desorganização estrutural. E a partir do ensaio de condutividade elétrica da manta carbonizada, concluiu-se que o material se comporta como um semi-condutor. O compósito de nanofibras de carbono/resina epóxi processado apresentou módulo de elasticidade de (3,79 ± 0,48) GPa, temperatura de transição vítrea (Tg) na faixa de 108,9 a 135,5°C, e um coeficiente de expansão térmica linear entre a faixa de 68 x 10-6/°C e 408 x 10-6/°C. / In recent years, reinforcement consisting of carbon nanostructures, such as carbon nanotubes, fullerenes, graphenes, and carbon nanofibers has been very researched due to its mechanical, electrical and thermal properties, besides having good thermal conductivity, mechanical resistance and high surface area. Since the carbon nanofibers comprise a continuous reinforcing with high specific surface area, associated with the fact that they can be obtained at a low cost and in large amounts, they have shown to be advantageous compared to traditional carbon nanotubes. Thus, the carbon nanofibers are excellent candidates in order to obtain advanced materials, and these can be used as reinforcements in composites with several applications such as for example, neurological and orthopedic implants, integrates in catalysts systems, devices for aerospace applications, among others. So, the main objective of this work is the processing of carbon nanofibers, using PAN as a precursor, obtained by the electrospinning process via polymer solution, with subsequent use for applications as reinforcement in polymer composites. In this work, PAN nanofibers were produced by electrospining with a diameter of approximately (375 ± 85) nm. The resulting residual weight after carbonization was approximately 38% in mass, with a diameters reduction of 50%, and the same showed a yield of 25%. From the analysis of the crystallinity structure of the carbonized material, it was found that the material presented a disordered structure. From the electrical conductivity results of the specimens, it was concluded that the material behaves as a semi-conductor. The epoxy resin/carbon nanofiber composite presented an elastic modulus value of (3.79 ± 0.48) GPa, a glass transition temperature (Tg) in the range from 108.9 to 135 5 ° C and a linear thermal expansion coefficient within the range of 68 x 10-6/°C and 408 x 10-6/°C.

Os resíduos orgânicos alimentares são um tipo de resíduo de difícil aproveitamento. Milhões de toneladas de lixo orgânico são descartados todos os anos, sobretudo os de origem alimentar, sendo que boa parte não é reaproveitada. Tradicionalmente, quando reaproveitados, esses resíduos são destinados à compostagem. No entanto, para que esse processo seja bemsucedido, é necessário que os resíduos sejam separados corretamente a fim de que a qualidade do produto final seja aceitável para o uso como fertilizante. Uma alternativa proposta de utilização dos resíduos alimentares consiste na produção de material carbonáceo obtido pela carbonização ou torrefação destes. Avaliam-se as propriedades e as características qualitativas e quantitativas desses materiais carbonáceos e seus derivados, como a composição, a resistência mecânica e a microestrutura. Tenciona-se, desse modo, contribuir para o conhecimento das possíveis aplicações desses carvões, materiais carbonosos e derivados em diversas áreas da indústria, inclusive na siderúrgica. / Millions of tons of organic waste are discarded every year, especially from food sources, and most of it is not reused. Traditionally, when reused, this kind of waste is destined for composting. However, for that procedure to be successful it is necessary that the waste is properly separated so that the quality of the final product is acceptable for fertilizer. An alternative reuse of food waste constitutes obtaining carbonaceous material by carbonization or torrefaction of this material. This work studies the charcoalmaking that uses these kind of residues, the characteristics of charcoals obtained, and the possible applications for these carbonaceous materials. The properties and the qualitative and quantitative characteristics of this object of study, such as its composition, its mechanical resistance and its microstructure, are evaluated. It is intended to contribute to the knowledge of the possible applications of these charcoals in several areas of industry, including in the steel industry.

M.Tech. (Chemistry) / This study investigated the functionalization of coke particles and their utilization for the preparation of coke-polymer composite. Looking at the possibility of using it for the removal of lead and chromium ions from their aqueous solutions. Due to various inorganic materials in coke, it was treated with acid to demineralize the ash content. The demineralized coke was further oxidized with hydrogen peroxide to add functional groups on its surface as well as in the bulk of coke particles before coating of the polymers. The composite preparation entails modifying the surface properties of coke with hydrophilic polymers like polyvinyl alcohol (PVA), poly ethylene glycol (PEG) and poly vinyl pyrrolidone (PVP) followed by the crosslinking to improve the interfacial interaction between the polymer and coke to make the synthesized composite stable in water. The structural composition of coke and modified coke was examined by FT-IR spectroscopy, X-ray diffraction, X-ray fluorescence, Raman Spectroscopy, thermal analysis and scanning electron microscopy combined with energy dispersive X-ray analysis. It was also observed that the modified coke samples have enhanced carbon reactivity which indicates that the non-carbon phases were removed by the treatment with acid. The adsorption studies for the removal of Pb (II) and Cr (III) ions from contaminated water was done in batch mode using variables such as pH, contact time and the initial concentration. The synthesized material was found to have better adsorption capacity as compared to raw coke. To understand the adsorption isotherm processes, Freundlich and Langmuir isotherms were applied. The monolayer adsorption capacity for the removal of lead ions was found to be 2.41 mg/g, 2.95 mg/g, 8.32 mg/g, 9.70 mg/g and 9.84 mg/g for raw coke, acid treated coke, PVA coated coke, PEG coated coke and PVP coated coke, respectively. The chromium monolayer adsorption capacity was found to be 9.48 mg/g, 9.94 mg/g, 35.84 mg/g, 32.79 mg/g and 34.13 mg/g for the same order of adsorbents mentioned for lead. Studies were carried out at the optimum pH of 6.0 for both the metal ions. The adsorption kinetic studies showed that both the metal ions followed pseudo second order rate equation and the adsorption equilibrium was attained in 60 minutes and 120 minutes for Pb (II) and Cr (III) ions, respectively.

Printing ink is a main component of the modern printer, and it has always been throughout the history of printing. Ink and toners are expensive replaceable components that inkjet and laser printers cannot function without. The digital printing industry, which is majorly composed of monochrome printing, is expected to increase by 225% by 2024 from a 2013 baseline (Smithers et al., 2014). Expenses aside, toner cartridges and ink cartridges pose an overlooked threat to the environment. Manufacturing, packaging, transporting, and waste disposal of printer ink and toners result in carbon dioxide emissions. The complete elimination of ink in monochrome printing is potentially viable with the patented new discoloration technique. The patent studies a discoloration method by carbonizing a paper’s surface (Alhashem et al., 2015). The printing method optimizes surface paper pyrolysis via laser heating. The aim is obtaining the darkest possible shade without compromising paper quality. The challenge is in creating a printed area from the paper material itself, rather than depositing ink on paper. A 75-watt CO2 laser engraving machine emitting a 10.6 μm wavelength beam for heating is used with low power settings to carbonize a fraction of the paper surface. The carbonization is essentially a combustion reaction. Solid fuel burns in three stages: drying, devolatilization (pyrolysis, or distillation phase), and lastly, the char (charcoal) combustion. These stages are driven by heat from the CO2 laser. Moving the laser rapidly above the paper surface arrests the reaction at the second stage, after the formation of blackened char. The control variables in the experimental method are laser power, speed, and the vertical position that affects the laser intensity. Computer software controls these variables. The discoloration of paper is quantified by measuring the light absorptivity using a UV-Vis-IR Spectrometer.

No description available.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22430号 / 工博第4691号 / 新制||工||1732(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 高岡 昌輝, 教授 米田 稔, 准教授 大下 和徹 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Consumers put higher demands on low environmental impact from the products they use, and the materials they consist of. As a result, more research is being made on finding environmentally friendly production techniques and materials. Hydrothermal carbonization (HTC) is a relatively environmentally friendly method that has been used in this study. Cellulose and pine, the latter, one sample with and one without bark, were carbonized at 220 °C and 240 °C for two hours. This generated solid carbon products that could be used in composites with the biopolymer Polylactide (PLA). The composites were thereafter extruded as filaments and used for 3D printing. X-ray powder diffraction (XRD), Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) showed that HTC of all precursors generated an amorphous carbon material, with carbon microspheres and increased aromaticity. Three different composites were produced from PLA and 0.1 wt% of the solid carbon products from all three precursors carbonized at 240 °C. Composites were also made from PLA and 1 wt% non-carbonized pine with bark, and 1 wt% of pine with bark carbonized at 240 °C. Filaments were extruded from neat PLA, as well as the composites of 0.1 wt% carbonized cellulose and 0.1 wt% carbonized pine with bark mentioned above. The filaments were used to 3D print six dog bones per filament according to the ISO standard ISO 527-2 1BA. There was one instance of clogging for each filament from the composite materials, but it was easily solved. No mechanical tests could be performed, although the 3D printed models’ physical properties were visually observed, and no deficiencies were found. Both extrusion and 3D printing were successful. / Konsumenter ställer högre krav på att material och produkter de använder har liten påverkan på miljön. Till följd av detta lägger forskningen mer resurser på att hitta miljövänliga tillverkningsmetoder och material. Hydrotermisk karbonisering (HTC) är en relativt miljövänlig process som har använts i denna studie. Tall (ett prov med och ett utan bark) samt cellulosa karboniserades vid 220 °C och 240 °C i två timmar, för att på detta vis producera en fast kolprodukt som kunde användas i en komposit med biopolymeren Polylaktid (PLA). Kompositen extruderades sedan till filament som användes vid 3D printing. Röntgenpulverdiffraktion (XRD), Svepelektronmikroskopi (SEM) och Fourier-transform infraröd spektroskopi (FTIR) visade på att HTC hade genererat amorfa kolmaterial, med mikrosfärer och ökad aromaticitet från både cellulosa och båda tallproverna. Samtliga produkter från karbonisering vid 240 °C användes för att göra tre olika kompositer med vardera 0,1 vikt% kolmaterial. Kompositer tillverkades även från PLA och 1 vikt% tall med bark, samt 1 vikt% tall med bark karboniserad vid 240 °C. Filament extruderades av ren PLA samt ovan nämnda kompositer med 0.1 vikt% karboniserad cellulosa och 0.1 vikt% karboniserad tall med bark. Dessa användes vid 3D printing för att skriva ut sex hundben per filament, enligt ISO standarden ISO 527-2 1BA. Vid ett tillfälle för vardera av de två kompositerna täpptes mynningen till 3D skrivaren igen av partiklar i filamenten. Detta löstes dock enkelt. Mekaniska tester kunde tyvärr inte utföras på hundbenen, men inga fysiska brister beskådades på dem. Både extrudering och 3D printing var lyckade.