Análise de falhas em materiais através de técnicas avançadas de microscopia

Chinaglia, C.R.; Correa, Carlos A.

doi:10.1590/s0104-14281997000300005

Cited by 4 publications

(4 citation statements)

References 1 publication

(1 reference statement)

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“…Os pontos brancos (EDS Spot 1) constituem depósitos do fotocatalisador TiO 2 , com teor de 42,35% de Ti, sendo pouco inferior aos 59,93% esperado para o Ti no cálculo teórico para o TiO 2 . As regiões mais escuras (EDS Spot 2), com teor de apenas 5,50%, são compatíveis com a matriz orgânica com sinais subsuperficiais 37 de fotocatalisador (Figura 3). De modo geral, acredita-se que possivelmente as partículas de TiO 2 ficaram envolvidas pelo alginato de cálcio, seja na porção interna, bem como na mais externa, sendo que o tempo de espera de estabilização e de amadurecimento contribuem para a formação de uma camada superficial de alginato de cálcio sobre toda a esfera.…”

Section: Análise Por Microscopia Eletrônica De Varredura (Mev)unclassified

Degradação fotocatalítica de tartrazina com TiO2 imobilizado em esferas de alginato

Dalponte¹,

Mathias²,

Jorge³

et al. 2016

Quim. Nova

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PHOTOCATALYTIC DEGRADATION OF TARTRAZINE WITH IMMOBILIZED TiO 2 IN ALGINATE BEADS. The potential of heterogeneous photocatalysis using TiO 2 immobilized in alginate beads was evaluated for the degradation of tartrazine yellow azo dye. The treatment was performed under the action of a high-pressure mercury vapor lamp of 125 W and the degradation performance was investigated with the absorbance supplied by a photocolorimeter. Alginate beads with TiO 2 were prepared and the catalyst was quantified by thermogravimetric analysis (TG) and characterized by scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) and specific area analysis (BET). The immobilization was performed as a very simple and reproductible technique. The bead diameter was approximately 1 mm and its surface presented a homogeneous dispersion of catalytic sites containing about 1-2% (w/w) of TiO 2 . The TiO 2 /alginate beads presented low density and can be easier separated than the TiO 2 dispersed from the reacting medium, remaining available to be reused in another batch. The dye degradation reached 30% after 120 minutes of irradiation, for the following conditions: alcaline pH (pH=9.0), 3 g of TiO 2 /alginate beads and 20 mol L -1 dye concentration.Keywords: heterogeneous photocatalysis; calcium alginate; azo dye. INTRODUÇÃOO descarte de efluentes com alto índice de coloração leva a alterações na quantidade e qualidade da luz que penetra nas camadas mais profundas dos corpos hídricos, alterando as condições da biota aquática, diminuindo a transparência da água e a penetração da luz solar, o que pode afetar a atividade fotossintética e o regime de solubilidade dos gases, principalmente próximos às regiões de descarga.1,2 Devido ao alto grau de aromaticidade das moléculas de corantes e à sua alta estabilidade, os métodos de tratamento biológi-cos são ineficientes para a descoloração e degradação. Esta estrutura recalcitrante também inibe o metabolismo de certos microrganismos presentes no tratamento biológico.3,4 Logo, outras técnicas de tratamento físico-químico se fazem necessárias, tais como coagulação com agentes químicos, adsorção em carvão ativado, ultrafiltração, osmose reversa, remoção com uso de resinas de troca iônica, etc. Todavia, essas operações constituem técnicas não destrutivas, uma vez que transferem os compostos orgânicos da água para outra fase, causando então uma poluição secundária. 5Neste contexto, a fotocatálise heterogênea surge como uma tecnologia muito efetiva e limpa, e que tem se destacado para a eliminação definitiva de poluentes orgânicos tóxicos de efluentes, sendo capaz de promover a degradação total de inúmeros compostos orgânicos a dióxido de carbono, água e íons inorgânicos provenientes de heteroátomos.5-8 O dióxido de titânio está muito próximo de ser um catalisador ideal para o processo de fotooxidação, pois apresenta muitas vantagens: não é tóxico, tem baixo custo, é abundante, é de simples obtenção e é resistente a processos fotocorrosivos. 5,7 No processo da fotocatálise, o TiO 2 pr...

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Section: Análise Por Microscopia Eletrônica De Varredura (Mev)unclassified

Degradação fotocatalítica de tartrazina com TiO2 imobilizado em esferas de alginato

Dalponte¹,

Mathias²,

Jorge³

et al. 2016

Quim. Nova

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“…In polymeric films, the presence of pores is decisive when determining gas permeation, as there is a greater possibility of the formation of channels that traverse through its thickness, but their detection demands advanced laboratory techniques such as energy-dispersive X-ray spectroscopy (EDS) [44] and positron annihilation lifetime spectroscopy (PALS) [45].…”

Section: Final Considerationsmentioning

confidence: 99%

Gas permeameter for polymers and nanocomposites: a new equipment

Pavani

Ferreira

2022

SN Appl. Sci.

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Information on the gas transport coefficients in the permeation of homogeneous semipermeable materials such as semicrystalline polymers under extreme pressures and temperatures is rarely found in the literature. Therefore, the objective of this work is to showcase innovation regarding the accuracy and usability of the medium pressure and temperature gas permeameter suitable for polymeric and polymeric nanocomposite plates built by the authors, which was tested with nitrogen at 1 MPa and 69 °C (342.15 K) permeating pure high density polyethylene samples (HDPE) and HDPE samples with added nanoclay, redoing the tests published in a previous work on the subject. The results were compared against data obtained previously and information present in the literature, validating the permeameter presented in this work, which is capable of analyzing gas permeability under the described conditions with greater accuracy and ease of operation than the previous model for the values of the transport coefficients of nitrogen permeating HDPE, demonstrating that the implemented improvements and advances were adequate, allowing the measurement of the transport properties of gases permeating polymeric and nanocomposite plates, necessary information for the design of risers for the transportation of oil and natural gas, for example.

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“…SEM images are threedimensional and suitable for analyzing and evaluating the surface area of polymer samples [23] . This tool investigates the fracture zone and tries correlating the topographical features of the sample surface [24,25] . Thus, the resulting photomicrographs characterized the surface topography aspects of castor oil-based PU with HA.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

Surface and micromechanical analysis of polyurethane plates with hydroxyapatite for bone structure

et al. 2022

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To analyze the surface topography and mechanical properties of a polyurethane derived from castor oil reinforced with hydroxyapatite (PU-HA) for bone fixation. The surface analysis was performed by Scanning Electron Microscopy (SEM) and the mechanical properties by Vickers microhardness and tensile tests. The SEM images showed that the PU surface presented important characteristics for materials intended for bone fixation, such as an irregular and porous surface. The analysis showed a surface with alternating areas with depressions and elevations of approximately 80±100 µm, presence of pores of 12 µm in size. The microhardness analysis showed values of 0.42±1.01 HV for PU-HA plates, lower in relation to the poly lactic-co-glycolic acid (PLGA) plate (control group). The elastic modulus and ultimate tensile strength of 317.4 MPa, and 35.57 MPa for PLGA sample, 1.187 MPa, and 0.29 MPa for PU-HA sample. The PU produced showed good surface properties, however demands better mechanical properties.

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Análise de falhas em materiais através de técnicas avançadas de microscopia

Cited by 4 publications

References 1 publication

Degradação fotocatalítica de tartrazina com TiO2 imobilizado em esferas de alginato

Degradação fotocatalítica de tartrazina com TiO2 imobilizado em esferas de alginato

Gas permeameter for polymers and nanocomposites: a new equipment

Surface and micromechanical analysis of polyurethane plates with hydroxyapatite for bone structure

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