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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Agora exibindo 1 - 9 de 9

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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)
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 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)
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 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)
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)
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.
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)
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.

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