Programa de Pós-Graduação em Ciência e Engenharia de Materiais - PPGCEM/Ananindeua
URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/12420
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Dissertação Acesso aberto (Open Access) Código de resposta rápida nanoestruturado impresso em 3D(Universidade Federal do Pará, 2023-07-12) OLIVEIRA, Dhonata Sebastião Caldas; REIS, Marcos Allan Leite dos; http://lattes.cnpq.br/8252507933374637; https://orcid.org/0000-0003-2226-2653Due to the Fourth Industrial Revolution, also known as Industry 4.0, factories increasingly have systems dependent on the Internet and communication technologies, which guarantees them unprecedented efficiency, but makes them vulnerable to cyber attacks. For this reason, cybersecurity it is an increasingly relevant topic, with technologies such as blockchain and quantum cryptography based on physically unclonable functions (PUFs) presenting themselves as alternatives in this area. In this sense, this work presents the synthesis of poly(acrylonitrile-butadiene-styrene) (ABS) nanocomposites with respectively 1 and 2 % by mass of carbon nanotubes (CNTs) for the 3D printing of the so-called NanoCodecs, which present Raman spectral signatures, classified as PUFs, which can be used as cryptographic keys generated by a code built in the Python programming language. For this, two solutions were prepared, the first with multi-walled CNTs functionalized with carboxylic acid in acetone, and the other with pure ABS pellets in this same solvent. After mixing these solutions and ultrasonic baths, the acetone was evaporated and ABS/NTC1%m/m and ABS/NTC2%m/m pellets were produced, which were used for the production of nanostructured filaments in an extruder. Then NanoCodecs as quick response code (QR code) and as round/square stamps were 3D printed. The electrical characterization of samples printed with nanostructured filaments showed a reduction in electrical resistance with an increase in the percentage by mass of CNTs. Despite this, the morphological characterization by Scanning Electron Microscopy showed that there is a low concentration of nanotubes on the surface of the samples, which indicates that they are dispersed throughout the volume of the samples. The vibrational characterization by Raman spectroscopy was used to identify the characteristics of pure materials, both ABS and NTCs, and compare with the Raman spectrum of the ABS/NTCs nanocomposite. As a result, there was an overlap of the vibrational modes of both materials, with emphasis on the shift to the right of the sub-band 𝐺𝑒𝑥𝑡 in 8 𝑐𝑚−1, which indicates that the nanotubes are compressed in the polymeric matrix. Finally, using nanocomposites as PUFs, it was possible to generate keys from the main vibrational modes of these materials: the D, G and 2D bands of nanotubes and the bands named as 1001-PS and 2239-PAN of ABS. Therefore, the results obtained indicate that NanoCodecs can be used as elements of ybersecurity in Industry 4.0, through cryptographic keys generated by the spectral analisys of the nanocoposite used for produtction of the NanoCodecs.Dissertação Acesso aberto (Open Access) Desenvolvimento de "língua eletrônica" nanoestruturada baseada em buckypaper e seu uso para autenticação de bebidas etílicas(Universidade Federal do Pará, 2023-03-06) FERREIRA, Luiza de Marilac Pantoja; REIS, Marcos Allan Leite dos; http://lattes.cnpq.br/8252507933374637; https://orcid.org/0000-0003-2226-2653; BARBOSA NETO, Newton Martins; http://lattes.cnpq.br/3177694073540758; https://orcid.org/0000-0001-9082-5433The development of electronic gadgets has become of great relevance for the detection of fraud in beverages such as wine, as illegal practices involving the addition of exogenous substances such as alcohol and dilution with water pose risks to human health as well as economic impacts. Thus, in this study, Buckypapers (BPs) films were developed based on pure Multi-Walled Carbon Nanotubes (pure-MWCNTs) and functionalized with Carboxylic Acid (COOH-MWCNTs) deposited through vacuum filtration on cellulosic filter paper for application as an element sensor in the analysis of ethylic beverages based grapes and açaí (unadulterated and adulterated with 1.0, 2.5, 5.0, 7.5 and 10% distilled water and ethyl alcohol). The morphological characterization of BPs by Scanning Electron Microscopy indicates the formation of dispersed COOH-MWCNTSs agglomerates on the surface and between the cellulosic fibers of the paper, as well as poor adhesion and non-uniform deposition of highly agglomerated pure-MWCNTs. Electrical resistance measurements were performed as a function of time (R × t) using the two-tip method, at room temperature, adding the analytes to the surface of the sensor element samples using a micropipette. The analysis of the response obtained through normalized relative resistance curves demonstrates a different behavior for BP-COOH-MWCNTs, obtaining a positive variation in the presence of Port and Açaí wines adulterated with water and a negative variation for adulteration with ethyl alcohol. Such behaviors were not observed in the BP-pure-MWCNTs, showing that the responses originate from the polar interactions established between the COOH groups and the adulterant molecules added to the wines, culminating in pronounced performance parameters for the BP-COOH-MWCNTs (response maximum of 5.67 ± 1.82 for unadulterated açaí ethyl beverage and maximum response and recovery times of 37.33 min and 50.58 min for Port wine adulterated with 5.0 and 10% distilled water, respectively). Data processing by PCA showed the ability of BP-COOH-MWCNTs to discriminate and recognize analytes and adulterants, indicating its potential application as a chemoresistive sensor element of low cost, easy handling and real-time response in an “Internet of Things” (IoT) device composing a nanostructured “electronic tongue” for ethyl beverage authentication.Dissertação Acesso aberto (Open Access) Desenvolvimento de sensor piezorresistivo nanoestruturado impresso em 3D(Universidade Federal do Pará, 2023-07-05) QUARESMA, Luciano José Barbosa; REIS, Marcos Allan Leite dos; http://lattes.cnpq.br/8252507933374637; https://orcid.org/0000-0003-2226-2653; FEIO, Waldeci Paraguassu; http://lattes.cnpq.br/3512689932467320; https://orcid.org/0000-0003-4980-4694The emergence of smart factories based on Industry 4.0 increases the automation and optimization of industrial processes in production chains. In this context, the integration between physical and digital systems depends on intelligent sensors, with greater sensitivity and integrated by the Internet of Things (IoT). The literature indicates that piezoresistive sensors can be produced by additive manufacturing (AM) and nanostructured with carbon nanotubes (NTCs), which generate a nanoelectromechanical system (NEMS) after its dispersion in the material. Thus, this work presents the development of a low-cost piezoresistive nanoelectromechanical sensor, produced by applying layers of NTCs on poly(acrylonitrile-butadiene-styrene) (ABS) parts printed by fused deposition modeling (FDM), integrable to the Industry 4.0 via IoT through ESP32 microcontrollers. For this, a diaphragm-type sensor device with dimensions 17.8, 17.8 and 5.5 𝑚𝑚 was developed, whose sensor element deformation occurs by pressing a button. After MA printing of the device parts, carboxylic acid functionalized multi-walled CNTs (MWCNT-COOH) were dispersed by ultrasonic bath in a solution with a concentration of 1 𝑚𝑔/𝑚𝑙 of acetone and dimethylformamide, in a ratio of 1 ∶ 1 in volume, for coating the sensor elements in successive layers with an aerograph. After the deposition of five layers of CNTs on the polymeric substrate, measurements of electrical resistance obtained with a picoammeter showed the percolation of the material in the second layer, with initial values above 10 𝑇 Ω and final values below 100 𝑘 𝑂𝑚𝑒𝑔𝑎 after the fifth layer, which occurs by the formation of conduction channels originating from the random arrangement of CNTs on the ABS surface, as observed by Field Emission Scanning Electron Microscopy (FEG-SEM). After that, the electrical resistance was measured during pressure cycles with progressive load and with maximum load, in which the sensor elements presented an operating range of 139.97 ± 0.46 to 363.25 ± 0.39 𝑘𝑃 𝑎. In the first test, the minimum sensitivity of 0.1 % and maximum sensitivity of 1.16 %. In the second, the highest average sensitivity was 0.63 ± 0.04 % and the lowest average response and recovery times were 0.55 ± 0.29 𝑠 and 12.29 ± 1.44 𝑠, respectively. Raman spectroscopy showed the overlapping of the signals of each material, in particular the ABS band at 1447 𝑐𝑚−1 which appears prominently between the NTCs 𝐷 and 𝐺 bands. Based on the piezoresistive response that the material presented from the NEMS generated by the deposition of NTCs on ABS, this concept of a load cell can be integrated into an ESP32 microcontroller board, making it an intelligent device with potential application in industrial systems. 4.0.Dissertação 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/0000-0003-2226-2653The 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.Dissertação Acesso aberto (Open Access) Eletrodeposição pulsada e caracterização de revestimentos de cobre/nanotubos de carbono em ligas de alumínio 3003 e 1350(Universidade Federal do Pará, 2025-06-25) SILVA, Alberto Solary da; SOUSA, Mário Edson Santos de; http://lattes.cnpq.br/4761512397509247; HTTPS://ORCID.ORG/0000-0002-7605-2371; REIS, Marcos Allan Leite dos; http://lattes.cnpq.br/8252507933374637; https://orcid.org/0000-0003-2226-2653The demand for more efficient and sustainable electrical systems has driven research toward innovative materials that enhance the properties of electrical conductors. Aluminum (Al) and its alloys are widely used in power transmission and distribution due to their low density and good electrical conductivity. The pursuit of improved electrical properties has led to the development of coatings that increase conductivity without compromising the lightweight nature of the material. This study presents an investigation into the anodization of Al substrates as a preparation step for nanostructured coatings, combined with pulsed current electrodeposition of a copper (Cu) and multi-walled carbon nanotube (MWCNT)-based nanocomposite, focusing on the correlation between electrical properties and microstructure. Experiments were conducted on Al 3003 alloy sheets, and on wires and cables made from Al 1350 alloy. Optimized anodization parameters were established using 100% H₂SO₄, direct current of 3 A, and 10 V applied for 2 hours. For the pulsed current electrodeposition, a concentration of 1 mg/mL of MWCNTs, an 80% duty cycle, 2 A, and 10 V were applied for 1 hour. Field Emission Gun Scanning Electron Microscopy (FEG-SEM) micrographs confirmed the formation of a uniform and porous aluminum oxide (Al₂O₃) layer, essential for coating adhesion, and revealed the homogeneous and effective distribution of the nanocomposite over the anodized surface. Energy Dispersive Spectroscopy (EDS) verified the presence of Cu and carbon (C) elements distributed throughout the coating layer. Raman spectroscopy identified characteristic vibrational modes of MWCNTs: D, G, and G′ bands, showing variations in intensity and bandwidth due to structural modifications induced by electrodeposition. X-ray Diffraction (XRD) analysis revealed the crystalline phases present in the coating and structural changes resulting from the surface treatment, confirming the integration of the nanocomposite into the metallic substrate. Electrical conductivity tests using the four-point Kelvin probe method, before and after coating, demonstrated a significant increase in electrical conductivity (σ), indicating improved charge transport efficiency due to the synergy between Cu and MWCNTs. Among the results, a ∼ 52.33% increase in surface electrical conductivity (σₛ) of the Al sheets and an increase in IACS from 67.76% to ∼ 73.5% in the coated wires stood out. Similarly, the average resistance of the coated cable decreased from 4.88×10⁻⁴ Ω to 1.934×10⁻⁴ Ω, a reduction of ∼ 60.37% compared to the uncoated cable. Statistical analyses supported these findings and confirmed their significance. Joule heat dissipation and ampacity calculations confirmed the superior performance of the coated material and its potential for application in power transmission and distribution systems. Therefore, the Cu-MWCNT nanocomposite coating obtained via pulsed current electrodeposition on anodized surfaces represents a promising approach for improving the electrical properties of Al-based conductors.Dissertação Acesso aberto (Open Access) Formação de heteroestruturas compostas por microtubos de Cu/Cu2O/CuO decorados com nanocristais de CoO(Universidade Federal do Pará, 2024-08-21) SANTOS, Suzilene Vasconcelos dos; PASCA, Gabriel Adolfo Cabrera; http://lattes.cnpq.br/5642784995274060; https://orcid.org/0000-0002-9411-0889A particularly important class of micro/nanostructured materials is that of transition metal oxides. In this work, copper and cobalt oxides are used to obtain micro/nanostructures. Copper (II) oxide (CuO) and copper (I) oxide (Cu2O) are p-type semiconductors, widely studied due to their peculiar characteristics and potential technological applications. Specifically, copper (Cu) microwires with approximately 50 μm in diameter and 4 cm in length, extracted from discarded cellphone earphones, were subjected to thermal treatments at 600°C with different synthesis parameters to obtain CuO microtubes. On the other hand, cobalt acetate was used in the synthesis of nanoparticles through the chemical method called thermal decomposition, which uses organometallic salts in organic solvents, being a suitable method for the synthesis of CoO nanostructures. Metallic cobalt and its oxides have been intensively studied due to numerous applications enhanced by their properties. CoO nanoparticles exhibit instability in the hexagonal close-packed Wurtzite structure (hcp - space group P63mc). This implies that, depending on the synthesis parameters, phase transition can occur, that is, from CoO-hcp to CoO-fcc (face-centered cubic phase - space group Fm3m), which is considered the most stable phase for CoO. However, in order to obtain a hierarchical structure of CuO microtubes decorated with CoO nanoparticles, this work uses different synthesis methodologies to produce a micro-nano-hierarchical structure. In this study, X-ray diffraction was used to identify the crystalline structures present in the microwires and nanoparticles, highlighting the influence of the time parameter on the phase transition of both structures. The morphological characterization of the samples was performed using scanning electron microscopy (for the microwires) and transmission electron microscopy (for the nanoparticles). Raman spectroscopy was also employed to obtain information about the sample surfaces. With these characterization techniques, it was possible to determine the elemental and structural composition of the microtubes and nanoparticles composed of copper and cobalt oxides, as well as to evaluate the influence of the laser on the nanoparticle samples. Thus, a Cu/Cu2O/CuO heterostructure with CoO monocrystals on the surface was developed, presenting potential sensory properties.Dissertação Acesso aberto (Open Access) Influência dos parâmetros de preenchimento, forma e reforço nanoestruturado em matriz polimérica de PLA impressos em 3D(Universidade Federal do Pará, 2024-04-08) FARIAS, Dorivane Cohen; REIS, Marcos Allan Leite dos; http://lattes.cnpq.br/8252507933374637; https://orcid.org/0000-0003-2226-2653With the advancement of Additive Manufacturing and its applications in various industrial sectors, it becomes increasingly important to investigate the processability parameters associated with this technology. Thus, the present study aimed to investigate the influence of shape (solid and honeycomb), infill patterns (concentric, hexagons, and triangles), and concentrations of Carbon Nanotubes - CNTs (1 and 2 wt%) in a polymeric matrix of Poly (Lactic Acid) - PLA. The material was fabricated using the Fusion Deposition Modeling - FDM technique. The CNTs, PLA, and nanocomposites were characterized by Scanning Electron Microscopy - SEM, X - Ray Diffraction (XRD), and Raman Spectroscopy. Mechanical properties were analyzed through tensile, compression, and Charpy impact tests. The results of the SEM analysis before and after mechanical testing show: voids, CNTs, cracks, pores, and fractures. XRD analysis reveals two diffraction peaks for CNTs at 2θ: 30.01° and 2θ: 50.03°, while PLA and nanocomposites exhibit predominantly amorphous phases. In Raman characterization, the vibrational bands of CNTs, PLA, and nanocomposites were deconvoluted into subbands. CNTs showed the following subbands: DL, DR, DLO, Dmiddle, Gout, Ginn, D', 2DL, 2DR, DL + Gout, and DR + Ginn, in PLA the most prominent subbands are associated with symmetric and asymmetric vibrations of CH3. In nanocomposites, the subbands manifest as overlap of the vibrational modes of their respective constituents (PLA and CNTs). The mechanical analyses of tensile, compression, and Charpy impact tests indicate that infill patterns, shapes, and nanoreinforcement influence the mechanical properties. In tensile testing, the concentric infill pattern exhibited better performance for both shapes, with 40.75 MPa for the solid shape and 9.76 MPa for the honeycomb shape. The nanocomposites in tensile testing showed lower performance compared to the matrix. In compression testing, the triangular infill pattern showed better performance, with 52.8 MPa for the solid shape and 20.8 MPa for the honeycomb shape. In compression testing, the nanocomposites exhibited higher strengths than the matrix, with the PLA/2%CNTs nanocomposite showing the best performance in the solid shape at 73.5 MPa, and in the honeycomb shape, the PLA/1%CNTs nanocomposite performed the best at 33.2 MPa. In Charpy impact testing for the solid shape, the infill patterns did not differ in performance. However, in the honeycomb shape, the hexagon pattern stood out, with 2.88 J/m. For the nanocomposites, in both shapes, the PLA/2%CNTs fraction showed better performance, with 3.8 J/m for the solid shape and 2.98 J/m for the honeycomb shape.Dissertação Acesso aberto (Open Access) Sensor quimiorresistor baseado em nanotubos de carbono para detecção de éter-amina(Universidade Federal do Pará, 2025-06-25) FERREIRA, Débora Ely Medeiros; REIS, Marcos Allan Leite dos; http://lattes.cnpq.br/8252507933374637; HTTPS://ORCID.ORG/0000-0003-2226-2653; CORREA PABÓN, Rosa Elvira; http://lattes.cnpq.br/1410157252579591; https://orcid.org/0000-0002-0635-9095The development of nanostructured sensors has become highly relevant for the detection of chemical and biological substances, as they require small concentrations and offer easy handling. In the context of detecting and reusing flocculants in iron ore flotation, Buckypapers (BPs) based on functionalized Multi-Walled Carbon Nanotubes (MWCNTs) were employed to serve as sensing elements in the investigation of samples containing deionized water (DW), ether-amine (EA), and salts (AlCl₃, FeO₄·7H₂O, CaCl₂·2H₂O, MgCl₂·6H₂O) at different pH levels. Morphological characterization of the BPs using Scanning Electron Microscopy revealed an aggregated organization of carbon nanotubes (CNTs), which appeared randomly distributed on the phenolic surface. Through chemoresistive testing, electrical resistance measurements over time (R × t) were obtained. The results, based on the sensor response (as a percentage increase) over time (seconds) for three cycles—each with 0.1 μL of the solutions prepared from DW, EA, sodium hydroxide (NaOH), and salts—showed that the sensor was able to distinguish between the solutions and their pH differences. It exhibited specific response (%), response time (s), and recovery time (s) for each solution tested. A notable increase in sensor response was observed with rising pH, with the solution containing 30 ppm EA + salts (pH 9.63) reaching an average response of 20.14%, an average response time of 188.60 s, and an average recovery time of 154.91 s, indicating that the sensor is more sensitive in alkaline environments. Vibrational analysis by Raman spectroscopy revealed sub-bands around the D band resulting from the chemical functionalization and solubilization processes of the MWCNTs, as well as sub-bands near the G band associated with vibrations of the inner and outer nanotube walls. For samples containing EA and salts, the results indicated charge transfer between the ether-amine and the outer layers of the CNTs in the BP. The presence of metallic salts influenced the G band profile, altering electron density and causing local distortions. Principal Component Analysis (PCA) showed that the distribution of scores could distinguish the 30 ppm EA samples with higher pH (9.76 and 10.70) and 30 ppm EA + salts (pH 9.63) from the NaOH samples (pH 9.80 and 10.74) and salt-only samples (pH 4.73 and 9.77), indicating the system's detection and differentiation capability toward ether-amine, NaOH, and salts. Thus, the nanostructured sensor demonstrated relevant results for EA detection and potential application in the industry to recover unutilized EA.