Dissertações em Ciência e Engenharia de Materiais (Mestrado) - PPGCEM/Ananindeua

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/12421

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Acesso aberto (Open Access)
Estudo da influência da incorporação dos resíduos de caulim nas propriedades tecnológicas de cerâmica marajoara para obtenção de tijolo ecológico
(Universidade Federal do Pará, 2025-07-30) BRITO, Fabio Moreira; CÂNDIDO, Verônica Scarpini; http://lattes.cnpq.br/8274665115727809; https://orcid.org/0000-0002-3926-0403; MONTEIRO, Sérgio Neves; http://lattes.cnpq.br/2962183322412029; https://orcid.org/0000-0003-1208-1234
The effects of global climate change are occurring at an unprecedented pace. For this reason, human activities urgently require a paradigm shift to halt this entropic process before the consequences become irreversible. In this context, the use of highly eco-efficient materials aims to conveniently neutralize CO₂. This study aims to incorporate Kaolin waste—KDI (clayey) and KAI (sandy)—into the properties and microstructures of clay mass, assessing its mechanical strength after firing at temperatures of 750 and 950 °C. Within this framework, six formulations were tested, varying from 0% to 50% kaolin waste. The specimens were uniaxially pressed into cylindrical shapes and then subjected to firing at 750 °C and 950 °C for 2 hours at peak temperature. The raw materials underwent tests that provided a comprehensive characterization of their properties, such as X-ray diffraction (XRD), X-ray fluorescence (XRF), optical microscopy (OM), scanning electron microscopy (SEM), and laser diffraction techniques (LD). After mixing and forming the materials into test specimens with different compositions, they were uniaxially pressed in cylindrical molds and subjected to compression testing. The results demonstrated the feasibility of using these wastes, showing favorable outcomes for their incorporation into red ceramics for the production of ceramic products in compliance with current standards.
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/0000-0003-2226-2653
The 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.
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/0000-0002-0635-9095
The 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.
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.
Acesso aberto (Open Access)
Estudo das propriedades de argamassa geopolimérica produzida com resíduos de caulim e escória de alto-forno da Região Amazônica
(Universidade Federal do Pará, 2025-02-27) SANTANA, Rayanne Oliveira Leão; SILVA, Alisson Clay Rios da; http://lattes.cnpq.br/7389345867032737; https://orcid.org/0000-0001-9186-2287
The growing demand for sustainable solutions in the construction sector has driven research into the use of industrial waste as alternatives to conventional materials. This study investigated the utilization of kaolin industry residues in the production of geopolymers, focusing on the substitution of soft metakaolin with flint metakaolin and conventional sand with sandy kaolin residue in geopolymer mortars. The research was conducted in three stages: first, a physicochemical characterization of the raw materials was performed, including tests to determine mineralogical, chemical, granulometric compositions, and specific mass. In the second stage, the substitution of soft metakaolin with flint metakaolin at different percentages (0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%) was evaluated, and the compressive strength of geopolymer pastes was analyzed. Although a linear relationship between the increase in flint metakaolin substitution and compressive strength was not observed, the highest strength (52 MPa) was achieved with the full substitution of soft metakaolin by flint metakaolin. In the third stage, geopolymer mortars were produced by combining geopolymer paste with aggregates, testing substitution percentages of conventional sand with sandy kaolin residue (0%, 25%, 50%, 75%, and 100%). Physical tests revealed that substituting 50% of the conventional aggregate with sandy residue resulted in a more compact matrix with lower water absorption, higher specific mass, and reduced porosity. The results showed that replacing 50% of conventional sand with sandy residue led to the highest compressive strength (46 MPa), suggesting that this proportion enhanced matrix densification and improved interaction between the residue and the paste. Morphological analysis using SEM confirmed that the formulation with 50% sand substitution presented a densely compacted matrix with good cohesion between the paste and aggregates and an adequate distribution of N-A-S-H and C-A-S-H gels. These findings highlight that partial replacement of sand with sandy kaolin residue improves the densification and strength of geopolymeric mortars while demonstrating the potential of flint metakaolin and sandy residue as sustainable alternatives in construction.
Acesso aberto (Open Access)
Estudo de rotas tecnológicas para a síntese de geopolímeros com adição de micropartículas de vidro: análise da influência do tamanho e forma das partículas
(Universidade Federal do Pará, 2025-02-14) MODESTO, Alex da Silva; SILVA, Alisson Clay Rios da; http://lattes.cnpq.br/7389345867032737; https://orcid.org/0000-0001-9186-2287
The sustainable construction of the future requires materials that consume less energy, emit fewer greenhouse gases and reuse waste that is harmful to the environment, such as discarded glass, one of the main waste products in the production chain. This research developed geopolymers, inorganic polymers formed by the activation of amorphous aluminosilicates in an alkaline medium, using me-takaolin and blast furnace slag as precursors and recycled glass microparticles as an additive. Com-positions were formulated with glass contents ranging from 0% to 60%, in particle size ranges of < 38 μm, 38-45 μm, 45-75 μm and 75-180 μm, and alkaline hydroxide and sodium silicate activators. Compression tests carried out on cylindrical specimens after 7 days of curing revealed that the addi-tion of 40% glass with a grain size of 38-45 μm resulted in an 80% increase in compressive strength compared to the unmodified material, reaching values of over 40 MPa. Microstructural analysis by SEM and EDS confirmed greater density and reduced porosity in the geopolymer matrix. Tensile adhesion tests also indicated the viability of the material as a substrate for coatings, meeting the demands of the construction industry. It is concluded that geopolymers with added recycled glass combine high mechanical performance and sustainability, promoting circular economy and repre-senting a viable alternative to the use of Portland cement.
Acesso aberto (Open Access)
Desenvolvimento de Redes Semi-Interpenetrantes de PCL-pHEMA-copaíba para potencial uso com scaffolds na Engenharia de Tecidos
(Universidade Federal do Pará, 2024-02-22) LIMA, Tainara de Paula de Lima; PASSOS, Marcele Fonseca; http://lattes.cnpq.br/0588450144351187; https://orcid.org/0000-0002-5616-2127
Tissue engineering is an alternative to replace organs and tissues in the biological system affected by an illness. Therefore, it is necessary to study the material used as a scaffold in depth. Among the materials in this area, polymers and hydrogels stand out, such as poly (ε-caprolactone) (PCL) and poly (2-hydroxyethyl methacrylate) (PHEMA), respectively. PCL is a bioresorbable, biodegradable, and biocompatible polymer. However, it is hydrophobic.On the other hand, pHEMA is a biocompatible and hydrophilic hydrogel but does not show good degradability. Furthermore, it is possible to intersperse bioactive compounds through the use of Amazonian vegetable oils in these structures to further enhance tissue regeneration and combat possible infections by microorganisms. Therefore, this work aimed to obtain and characterize PCL-PHEMA-copaíba semi-IPN networks for scaffolds in tissue engineering using the rotospinning technique. The results successfully demonstrated the processing of PCL fibers (with and without copaiba oil) and the formation of PCL-C-PHEMA semi-IPN networks. Gas chromatography confirmed the presence of bioactive components in copaiba essential oil, the majority being (β)-caryophyllene (40.75%). The FTIR spectrum showed interactions of the materials' functional groups, confirming the incorporation of the oil into the PCL structure and the formation of semi-interpenetrating networks. Micrographs and topographies revealed tangled and disorganized microfibers in all samples, with different diameters, porosities, and roughness. The PCL, PCL-C, and PCL-C-PHEMA samples presented fiber diameters ranging from 18.40 to 19.50 μm, 3.11 to 24.44 μm, and 6.29 to 8.14 μm, respectively. Contact angle analyses (PCL: 86.96°, PCL-C: 93.99°, PCL-PHEMA: 29.42°, and PCL-C-PHEMA: 56.02°) and swelling test (PCL: 4.49%, PCL-C: 2.73%, PCL-PHEMA: 21.57%, and PCL-C-PHEMA: 10.11%) demonstrated that the addition of the hydrogel to the PCL structure optimized the hydrophilic properties of material. The sol-gel tests indicated that the PCL-PHEMA and PCL-C-PHEMA materials presented 73.5 74.3% gel fractions. Thermograms confirmed that the material did not significantly change in thermal stability with the addition of the hydrogel and oil. Microbiological tests confirmed the antimicrobial action of copaiba oil, PCL-C-PHEMA, and PCL-C scaffolds against the gram-positive bacterium Staphylococcus aureus, with an inhibition halo of 9, 7, and 5 mm, respectively. Moreover, the cytotoxicity tests concluded that the PCL, PCL-PHEMA, and PCL-C scaffolds showed good cell viability. However, optimizing the photopolymerization process of the semi-IPN network is necessary, given that the PCL-C-PHEMA materials were moderately toxic. Finally, a new biomaterial is expected to be developed for use in tissue engineering, valuing the use of natural Amazonian resources.
Acesso aberto (Open Access)
Avaliação microestrutural e mecânica das fibras de cotia e dos compósitos de matriz poliéster
(Universidade Federal do Pará, 2025-01-20) NASCIMENTO, Damares da Cruz Barbosa; OLIVEIRA, Michel Picanço; http://lattes.cnpq.br/6383844066460475; https://orcid.org/0000-0001-9241-0194; CANDIDO, Verônica Scarpini; http://lattes.cnpq.br/8274665115727809; https://orcid.org/0000-0002-3926-0403
The search for sustainable and low-cost materials has driven the use of natural fibers in the development of polymer composites, due to their mechanical and sustainable properties. The aim of this work is to study and characterize a new natural fiber, as well as to study the mechanical properties of composites made with in natura fibres (FC) and mercerized fibres (FM) in volumetric percentages of 10, 20 and 30%. The fibres and composites were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Thermogravimetry (TGA), Scanning Calorimetry (DSC), Energy Dispersive Spectroscopy (EDS) and Raman Spectroscopy, as well as mechanical characterization. The physical characterization of the fiber indicated an average density of around 0.34 g/cm3. The FTIR of the FC and FM fibers indicated chemical structural changes, which were confirmed with Raman, SEM and EDS. The thermal stability of Cotia fiber in natura was close to 145 and 272 ºC. The mechanical properties of the FC and FM fibers showed average strengths of around 151.32 and 99.98 MPa, respectively. The FTIR and Raman scans of the composites showed few changes related to the variation in chemical treatment, but differences when percentages of fibers were added. The tensile and flexural results indicated that the CF fibers were stronger and stiffer in relation to the matrix than the modified fibers. The SEM confirmed the existence of defects and flaws that caused early rupture of the composites with FM fibers. The single and double F ANOVA confirmed that both factors, chemical modification and increase in volume percentage, had an impact on the final properties. Although the results of the FM fibers did not have a positive impact, the properties of the in natura fibers stand out as efficient reinforcements for engineering applications.
Acesso aberto (Open Access)
Desenvolvimento e caracterização de bioplásticos de fécula de mandioca com extrato alcoólico de Vismia Guianensis
(Universidade Federal do Pará, 2024-08-27) SANTOS, Josiel Ferreira; PASCA, Gabriel Adolfo Cabrera; http://lattes.cnpq.br/5642784995274060; https://orcid.org/0000-0002-9411-0889
This work investigates the incorporation of the alcoholic extract of Vismia Guianensis (EAVG) cassava starch, aiming to improve its bioplastic properties. Cassava starch was dissolved in distilled water at the following concentrations with 0.2%, 0.5% and 1.0% EAVG under controlled temperature at the gelatinization point (~70 °C) and then molded to form bioplastics. The prepared samples were characterized by Attenuated Total Reflectance/Fourier Transform Infrared Spectroscopy (ATR/FTIR), Thermogravimetric and Thermal Differential Analysis (TGA-DTA), X-ray Diffraction (XRD), Scanning Electron Microscopy/Energy Spectroscopy Dispersive (SEM/EDS), Atomic Force Microscopy (AFM) and mechanical assays, providing insights into chemical composition, thermal stability, crystallinity, surface morphology and mechanical properties. These techniques comprehensively characterized cassava starch bioplastics with EAVG addition, highlighting their enhanced mechanical properties. The results demonstrated that EAVG played an effective role as a plasticizer, increasing the flexibility, resistance and stability of the biofilm that has a thickness of 0.8 mm, and supports a traction of 4.19 to 18.43 MPa. This study justifies EAVG as a promising additive for the production of biocompatible and sustainable materials, suitable for numerous applications in biodegradable plastics. EAVG presents a path forward for the advancement of bioplastics with improved mechanical, thermal and functional properties, with a promising future in terms of their contribution to new developments in these areas.
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/0000-0003-2226-2653
With 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.
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/0000-0002-9411-0889
A 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.
Acesso aberto (Open Access)
Síntese e Caracterização da Zeólita Ferrierita (FER) a partir de resíduo caulinítico: a influência dos parâmetros do processo
(Universidade Federal do Pará, 2024-06-06) VILHENA, Thefeson Oliveira; MAIA, Ana Áurea Barreto; http://lattes.cnpq.br/0820112425394964; https://orcid.org/0000-0002-1880-1442
The present work addresses the synthesis of ferrierite zeolite from kaolin residue from the Amazon region. Ferrierite is a high-silica zeolite with a topology considered complex due to its structure, which presents a three-dimensional arrangement of atoms with intersecting perpendicular channels. It is widely used in catalysis, adsorption, ion exchange, among other processes. Its synthesis from alternative materials, such as kaolin residue, offers a recyclable and cost-reducing approach. Thus, kaolin residue from the Amazon was used as a source of Si and Al for the synthesis of ferrierite. In this context, thermal treatment of the kaolin residue was carried out to obtain metakaolinite for the formation of the reaction mixture. Since the Si/Al ratio of metakaolinite was insufficient to achieve the objectives, silica gel was added to the reaction mixture, along with other reagents, sources of other necessary elements/constituents, such as compounds with compensating cations (Na+ and K+) and a structural directing agent (ethylenediamine). The methodology of the IZA (International Zeolite Association) was used for the synthesis of ferrierite, and to reduce the synthesis time, an aging step of the silica gel solution was added to make it more reactive. The hydrothermal process took place at a constant temperature of 180°C. The research investigates the influence of different process parameters, such as aging time and synthesis time of ferrierite, as well as the combined use of different compensating cations. The products were characterized by X-ray diffraction, scanning electron microscopy, infrared spectroscopy, and thermal analysis. The results showed that ferrierite was effectively synthesized from 48 hours onwards. However, with the extension of the synthesis time, ferrierite with higher crystallinity was obtained. The use of different compensating cations also led to the formation of the ferrierite phase with the prolonged synthesis time. Furthermore, the research highlighted the importance of the aging step of the silica gel solution, which proved to be very effective for the synthesis of ferrierite zeolite.
Acesso aberto (Open Access)
Produção de agregados sintéticos para construção civil a partir de materiais geopoliméricos
(Universidade Federal do Pará, 2023-06-20) CRUZ, Kamila Sindy Pinheiro da; SILVA, Alisson Clay Rios da; http://lattes.cnpq.br/7389345867032737; http://lattes.cnpq.br/7389345867032737
The civil construction industry is one of the sectors of the economy that consume the most natural resources, from the production of inputs to the execution of the work, which can significantly affect the environment and the quality of life of the population. Geopolymers are inorganic polymers with great ecological potential, produced from aluminosilicates and synthesized by alkaline solutions, providing the material with better mechanical resistance. Geopolymeric cement is a high-tech material developed using clay minerals, with characteristics such as durability, mechanical resistance, strong adhesion, heat resistance, in addition to being easily mixed and applied. The present study sought, through a correct proportion of the components that constitute the geopolymer, the production of a Geopolymeric Synthetic Aggregate (ASG), making variations with percentages of blast furnace slag and variations in the alkaline concentration of sodium hydroxide (NaOH). Soon after, physical tests were carried out on the powdered materials to verify the fineness index, loss on fire and moisture content of kaolin, metakaolin and blast furnace slag. The samples underwent characterization and the main analyzes involved in the process were: X-ray diffraction (DRX), infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and EDS. A compression test was also carried out on the geopolymer synthetic aggregate specimen. The results of the compressive strength test indicated that the specimen with a percentage of 35% blast furnace slag and an alkaline concentration of sodium hydroxide at 10 molar presented better results. In the analysis of the microstructure of the paste, a dense morphology was observed, which gives the material high resistance to compression.
Acesso aberto (Open Access)
Caracterização de tintas industriais aplicadas na região amazônica a partir de análises físico-químicas, mecânicas e de durabilidade
(Universidade Federal do Pará, 2024-02-28) LUCAS, Mathaus Moraes; SILVA, Alisson Clay Rios da; http://lattes.cnpq.br/7389345867032737; https://orcid.org/0000-0001-9186-2287
In Brazil, the industrial sector of paints and varnishes is among the five largest in the market. The manufacture of paints for various applications, with technology and technical responsibility, equals the most advanced global production centers. The durability of a paint refers to its resistance to weathering. For weathering, a weather-resistant paint is necessary so that fading does not occur on the substrate where it will be used, which can occur among some factors, due to the incidence of sunlight and heavy rains. The North region, with high rainfall, influenced by instability lines, presents significant spatial and seasonal heterogeneity of rainfall and has the highest annual rainfall total. Given this reality, a paint commercially applied in the Amazon region was developed. In the standard formulation, variations of mineral loads (Kaolin, Dolomite and Precipitated Calcium Carbonate) were made and subsequently analyses and tests were carried out to evaluate the performance of this paint, compared with the original formulation, such as abrasion resistance and weathering resistance. The paint production methodology will be according to Castro (2009) using Hare’s technique (1974). The characterization of the paints in the fresh state was carried out through the Viscosity, pH and specific weight tests, while the characterization of the paints in the hardened state was carried out through the abrasion resistance tests, weathering resistance test and Scanning Electron Microscopy. The physico-chemical tests revealed that, in relation to Stormer viscosity, all formulations exceeded the standard (130 KU), with the exception of the paints containing 30% Dolomite, 15% PCC, 15% Dolomite and the ternary combination of 5% Kaolin, 5% Dolomite and 20% PCC. As for the specific weight, the formulation that came closest to the standard was the binary paint with 15% Kaolin and 15% PCC, presenting an average value of 1.43 g/cm³. In terms of pH, all formulations showed alkalinity, with values ranging between 7.5 and 9.6. After a period of exposure of 180 days, none of the mixtures, including the standard formulation, showed the formation of pathologies, demonstrating resistance to weathering. The formulations with 30% Dolomite; 15% PCC and 15% Dolomite; 5% PCC, 5% Kaolin and 20% Dolomite; 10% Kaolin, 10% PCC and 10% Dolomite, exhibited respectively 300, 290, 240, 270 cycles of abrasion resistance, indicating the potential of these paints for a variety of applications, such as floor paints, external paints and road paints.
Acesso aberto (Open Access)
Amido termoplástico: obtenção de nanocompósitos de amido de araruta termoplastificado com nanopartículas de óxido de zinco
(Universidade Federal do Pará, 2024-02-07) PINTO, Bianca Corrêa; PAULA, Marcos Vinícius da Silva; http://lattes.cnpq.br/7538211324097974; MAIA, Ana Áurea Barreto; http://lattes.cnpq.br/0820112425394964; https://orcid.org/0000-0002-1880-1442
The search for new materials with comparable performance to synthetics has driven the development of sustainable and biodegradable materials. The growing demand has stimulated the creation of innovative materials, such as starch-based films, biopolymers, and others, which offer excellent mechanical and barrier properties while being environmentally friendly. To achieve higher levels of sustainability, starch-based films, enriched with new components, gain prominence as possible candidates for food packaging applications. In this context, the present study aims to obtain and characterize thermoplasticized nanocomposites with arrowroot starch (TPA) and zinc oxide nanoparticles (ZnO NPs) in different proportions (1%, 3% and 5%). Films without ZnO NPs were used as controls. The thermoplasticized starch films were made using the casting solution technique (solvent evaporation). They were evaluated for the concentration of ZnO NPs, and were also submitted to laboratory techniques, such as moisture, solubility and swelling tests. In addition, they were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and tensile, strain at break and modulus of elasticity tests. For the moisture test, the results revealed that the addition of 1, 3 and 5% of ZnO NPs to the polymeric matrix provided a gradual decrease in the percentage of moisture when compared to the control TPA film. This fact is attributed to the interfacial interaction between the ZnO NPs and the arrowroot starch matrix, which in turn hinders the interaction of water molecules with the nanocomposite film. For the percentage of solubility of the films, a small change was observed after the addition of the NPs ZnO to the starch matrix, which becomes important for the maintenance of products stored in food packaging as well as the stability of the polymeric films. As for the swelling test, for the 1% TPA, 3% TPA and 5% TPA films, it was verified that when the SPL was added, they presented smaller variations compared to the TPA film containing only arrowroot starch in the polymeric matrix. In view of the above, the micrographs obtained by SEM revealed the presence of randomly dispersed aggregates of ZnO NPs in the polymeric matrix of arrowroot starch. The stress properties tests were conducted in 5 replicates, with a speed of 5 mm/min. The TPA film showed an average of 0.34 MPa and 59.80% for tensile strength and deformation at break, respectively. The incorporation of ZnO nanoparticles into the arrowroot starch matrix resulted in an increase in the tensile strength and deformation of TPA 1%, TPA 3% and TPA 5% films compared to TPA film. The mean strength for the films TPA 1%, TPA 3% and TPA 5% were 0.42 MPa, 0.45 MPa and 0.60 MPa, respectively. In addition, the mean strain at break for TPA 1%, TPA 3% and TPA 5% films were 77.14%, 86.34% and 86.05%, respectively. The FTIR spectra exhibited the same spectral behavior. This phenomenon is due to the presence of high starch content in the polymeric matrix of the films. The thermal stability for TPA, TPA1%, TPA 3% and TPA 5% films was investigated by thermogravimetric analysis (TGA). The results obtained for the TPA1%, TPA 3% and TPA 5% films presented similar data to the thermal stability of the TPA film and showed that the addition of ZnO NPs to the polymeric matrix did not cause a significant decrease in them. The results showed that it is possible to use the films produced in this work in the packaging sector.
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/0000-0003-2226-2653
Due 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.
Acesso aberto (Open Access)
Avaliação da eficácia dos óleos essenciais das especies piper divaricatum e eugenia caryophyllus como inibidores de corrosão em aço carbono
(Universidade Federal do Pará, 2023-07-13) MONTEIRO, Heloise Leal; PAULA, Marcos Vinicius da Silva; http://lattes.cnpq.br/7538211324097974; MAIA, Ana Áurea Barreto; http://lattes.cnpq.br/0820112425394964; https://orcid.org/0000-0002-1880-1442
This research reports the evaluation of essential oils (EOs) such as those from the plant Piper divaricatum and Clove (button) Eugenia caryophyllus, as green corrosion inhibitors in metallic materials precisely in this work, carbon steel, these oils being considered environmentally sustainable. Corrosion tests were carried out in corrosive media such as 1M HCl and 3.5% NaCl, the concentrations used for both essential oils were 0.5g/L; 1g/L; 2g/L and 4g/L, for periods of time such as 24h and 7 days. The method used to evaluate the efficiency of the oils was gravimetric (weight loss). The Scanning Electron Microscopy technique of the field emission gun type (SEM-FEG) was conducted to investigate the surface of the specimen, while its chemical composition was obtained through Electron Dispersion Spectroscopy (EDS). In this work, several aspects were discussed, such as the efficiency in relation to the time exposed to the test specimen to corrosive media and factors such as the adsorption isotherm of the oils on the metal surface, in addition to calculations of the corrosion rate of the test specimens in the absence and presence of inhibitors and their relationship with the oil concentrations used. The studies indicated that the essential oils of Piper divaricatum and Clove (Eugenia caryophyllus) showed excellent results in an acid medium of up to 98.3% for the concentration of 2g/L of Piper divaricatum EO in 24h, and 89.5% for the concentration of 1g/L of Eugenia caryophyllus EO in 7 days. In the neutral medium, the highest percentages of inhibition were 61.1% for the concentration of 0.5g/L of EO from Piper divaricatum in 24h, and 83.3% for the concentration of 1g/L of EO from Eugenia caryophyllus in 24h. the isotherms of the oils followed the Langmuir adsorption model, where both oils adsorbed on the metal surface, the best results of isotherms were for the acid medium, for the neutral medium due to the high variability of the data it was not possible to establish a consistent correlation. In view of the proposed results, it was possible to conclude that the essential oils of P. divaricatum and E. caryophyllus have the potential to be used as corrosion inhibitors mainly in an acid medium, thus providing new alternatives in order to reduce the toxicity of this process in comparison to inhibitors already on the market.
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/0000-0003-4980-4694
The 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.
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)
Estudo das propriedades mecânicas e microestruturais de materiais cimentícios geopoliméricos produzidos a partir de metacaulim e escória de alto forno
(Universidade Federal do Pará, 2023-06-21) ALMEIDA, Bianca Mendes; SILVA, Alisson Clay Rios da; http://lattes.cnpq.br/7389345867032737; https://orcid.org/0000-0001-9186-2287
The environmental impacts caused by the production of Portland Cement point to the urgency of reducing the use of this binder mainly due to the CO2 emission and energy consumption that occur during its production process. In the search for alternative materials, geopolymeric cement has shown promise, both in terms of mechanical performance and conservation of natural resources. These cements are obtained from natural raw materials containing aluminosilicates activated by an alkaline solution. In this work, geopolymeric cement paste, mortar and concrete were developed using metakaolin, blast furnace slag and alkaline solution of sodium hydroxide and sodium silicate. The main objectives included evaluating the influence of blast furnace slag on the mechanical properties of geopolymer pastes, varying its addition in mass (30% to 60%), evaluating the influence of sand in geopolymer mortar varying its addition in the paste with better performance of 20% to 70%, and finally, the addition of gravel 0 in two mixtures. The results showed that the paste reached a maximum compressive strength of 36.5 MPa with 35% slag in the matrix. This value rose to 41.15 MPa in the mortar with the incorporation of 40% sand. For concrete, the best result was found for the mixture that contained less crushed stone. The results of the concrete were compared with the CPV-ARI Portland cement concrete by setting some dosing parameters such as binder consumption and water/binder ratio. Other properties investigated included setting time, slump, flexural tensile strength and microstructural analysis by SEM. Geopolymeric concrete was superior to Portland by up to 21.16%, reaching compressive strength of 41.8 MPa, flexural traction of 4.87 MPa and better matrix/aggregate adhesion in the mixture with less addition of gravel 0. The results obtained for geopolymers enable their application in civil works that demand materials that reach high strenght in the initial ages, precast and paving industries.