Navegando por Assunto "Nanocomposite"

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Acesso aberto (Open Access)
Desenvolvimento de ligas de alumínio nanoestruturadas para a utilização em cabos elétricos
(Universidade Federal do Pará, 2023-03-15) PRAZERES, Emerson Rodrigues; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968; BRAGA, Eduardo de Magalhães; http://lattes.cnpq.br/4783553888547500
Aluminum nanocomposites demonstrate the ability to improve mechanical properties, thermal and electrical conductivity. For aluminum, the incorporation of multi-walled carbon nanotubes (NTCPM) using conventional melting methods is an old problem, due to disintegration of the walls of carbon nanotubes when subjected to high temperatures. In this study, aluminum nanocomposites were manufactured by the conventional casting method, using stainless steel powder (304LSS), nanostructured silicon and nickel. The carbon nanotubes were treated with hydrogen peroxide, allowing adhesion by polar interaction with the particles of the metallic powders. The nanostructured compounds were added to the aluminum matrix by means of conventional casting. After obtaining the material as a melt, it went through the machining process to a diameter of 18.5 mm and then through the cold working process until a diameter of 3.0 mm was obtained. The alloys were characterized mechanically through tensile and microhardness tests, electrically through electrical resistance tests, using a 2-point kelvin bridge, and structurally through macrostructure and microstructure analyses. The 304LSS powder added alloying elements, refined the grains and the NTC improved electrical conductor performance, with electrical conductivity gains in the range of 10%. Associates associated with carbon-associated components not linked to chains of protein chains are compounds of carbon, associated with proteins, aggregates, associated with carbon, associated with proteins, associated with significant proteins in the LRT. The alloys with Ni and carbon nanotubes contributed to significant gains in electrical conductivity and LRT, with the alloy with 2% nickel and 0.1% NTC showing gains of approximately 8% in electrical and mechanical properties. Nanostructured alloys were also superior in terms of electrical and mechanical properties than commercial alloys.
Acesso aberto (Open Access)
Desenvolvimento de termosensores nanoestruturados impressos em 3D
(Universidade Federal do Pará, 2023-06-26) SANTOS, Leandro José Sena; REIS, Marcos Allan Leite dos; http://lattes.cnpq.br/8252507933374637; https://orcid.org/0000-0003-2226-2653
The market for temperature sensors and other related devices has grown significantly in recent years. It is estimated that there will be an annual growth rate of 11% between 2019 and 2026. This growth has sparked interest in studies focusing on alternative nanosensors that offer better portability, sustainability, and may contribute to achieving the Sustainable Development Goals (SDGs). This work presents the development of four sensors based on Poly (lactic acid) - PLA and Carbon Nanotubes - CNTs, produced using additive manufacturing. These sensors are designed for monitoring body temperature (35 to 45ºC) and cold room temperatures (5°C to -40°C), covering an active area of 15cm2. One of these sensors was developed using only PLA as a control sample, while the others were nanostructured by adding two different types of inks containing CNTs. The synthesis of these sensors was performed through 3D printing using Fused Deposition Modeling (FDM) technology, with a specific synthesis method for each sensor. Through morphological, vibrational, and electrical characterizations, the devices/sensors exhibited thermoresistive and thermoelectric responses to temperature variations. Electronic microscopy and vibrational Raman spectroscopy analyses of the nanocomposite samples revealed the successful incorporation of CNTs into the PLA matrix, as evident from their characteristic vibrational spectra. The sensors demonstrated a Seebeck coefficient of 1.33μV/K under temperature gradients of 300K, and a maximum thermoresistive response of -4.35± 0.15% at approximately 45°C. Thus, such developed devices exhibited the behavior of thermistors and thermocouples, making them a promising alternative for implementation in cold rooms and Home Health systems.
Acesso aberto (Open Access)
Reforço superficial em alumínio fundido por nanotubos de carbono via tratamento de solubilização
(Universidade Federal do Pará, 2021-10-14) BRITO, Paulo Roberto de Oliveira; REIS, Marcos Allan Leite dos; http://lattes.cnpq.br/8252507933374637
Carbon nanotubes (CNTs) are noteworthy, as they reinforce the metallic matrix, due to mechanical properties, such as the ~ 1.0 TPa Young module. To improve the maintenance of the commercially pure aluminum surface, multi-walled carbon nanotubes (MWCNTs) were incorporated into the aluminum surface with heat treatment by solid solubilization, in order to improve the surface properties of aluminum. The aluminum samples were subjected to chemically attacked with the Keller reagent, for a period of 30, 60 and 120 seconds, and soon after the roughness assessment was carried out, and then they were placed in a container containing NTCs, being subjected to a 640°C for one hour. Afterwards, the morphology was evaluated in the scanning electron microscope, where an aggregate of NTCs was observed, the DRX was performed to evaluate the addition of the NTCs in the matrix, and the Raman Spectrum that evaluated the charge transfer to the matrix. Microhardness was performed to evaluate the result of the incorporation of the NTCs in the matrix. The results obtained show that the incorporation of CNTs in the aluminum matrix increases the hardness in approximately 20% of the surface, in comparison with the control sample. The process of incorporating CNTs into the aluminum matrix by solubilization is a promising, simple and inexpensive alternative to improve the durability of the aluminum surface.
Acesso aberto (Open Access)
Síntese e caracterização de nanocompósitos poliméricos biodegradáveis para aplicação no setor de embalagens
(Universidade Federal do Pará, 2025-03-28) RAMOS JÚNIOR, Gilberto Sérgio da Silva; ALVES JÚNIOR, Severino; http://lattes.cnpq.br/9563158536061549; HTTPS://ORCID.ORG/0000-0002-8092-4224; PAULA, Marcos Vinícius da Silva; http://lattes.cnpq.br/7538211324097974
The search for more effective methods for food preservation has improved in recent years, which has led to the development of technologies that aim to extend the durability and ensure the stability of food products. Emerging solutions include the use and development of active packaging, which interacts directly with food, tending to increase its shelf life. And with the growing focus on sustainability, films made from blends of natural polymers together with more versatile polymers, with the addition of reinforcements, are becoming a promising alternative for the production of food packaging. In this scenario, this study seeks to produce and characterize nanocomposites composed of arrowroot starch, carboxymethyl cellulose (CMC), glycerol and citric acid, reinforced with zinc oxide nanoparticles in different concentrations (0%, 0.5%, 2% and 5% w/w), with the aim of evaluating their potential for applications in more sustainable and efficient food packaging. The films were obtained by the casting solution technique (solvent evaporation) and characterized by experimental techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), tensile test to analyze their mechanical properties, moisture percentage, swelling and solubility were analyzed, in addition to performing tests to study their biodegradability behavior in natural soil and their practical application as bread packaging. In the visual aspect, all the films obtained presented considerable optical transparency. The results demonstrated that in a period between 18 and 20 days buried in natural soil, total degradation was observed in all the films produced. The addition of ZnO NPs as a reinforcing agent in arrowroot starch and CMC films promoted an improvement in tensile strength from 1,75 to 35,84 MPa and in the elastic modulus from 5,79 to 1142,29 MPa. Finally, during the nine weeks of application of the films as bread packaging, no macroscopic changes characteristic of colonization by microorganisms, such as fungi, were observed. Thus, the results demonstrate that the nanocomposite films increased the shelf life of bread for a considerable period and can be effectively used as active packaging for bread storage.