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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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)
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)
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)
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)
Caracterização do tecido fibroso de tururi e avaliação de propriedades mecânicas de compósitos de matriz poliéster reforçados com tecido fibroso de tururi
(Universidade Federal do Pará, 2023-01-30) SANTOS, Avener Gleidson Andrade; CÂNDIDO, Verônica Scarpini; http://lattes.cnpq.br/8274665115727809; https://orcid.org/0000-0002-3926-0403
In recent decades, the search for materials with high mechanical performance and that are in accordance with sustainability requirements has become increasing. In the context of sustainability, the United Nations (UN) established in 2015 the Sustainable Development Goals (SDGs), in order to guide the paths to sustainable development. The use of waste to produce new materials is beneficial, because the use of these materials represents a solution for environmentally friendly disposal, thus covering the requirements established by the SDGs. The use of natural fibers in the production of new materials has increased significantly in the last decade. The use of natural fibers as reinforcement in polymer matrix composites is already well established. This is due to the fact that some fibers have high mechanical performance and good thermal stability, two highly attractive properties in composite materials. Composites reinforced with natural fibers have a vast field of application, and can be used in civil construction, aerospace, and automotive industries, among others. In this scenario, the use of tururi fabric as a reinforcement agent in composites of polymeric matrix emerges as a viable alternative for sustainable disposal of this waste coming from the harvesting stage of its fruits. Thus, this study aims to characterize the tururi fibrous tissue by optical microscopy, scanning electron microscopy, X-ray diffraction, thermogravimetric analysis and Fourier transform infrared spectroscopy (FTIR), as well as to determine physical properties such as density, moisture content and weight. The composites were produced using a 2.5, 5.0 and 7.5% by mass percentage of reinforcement. Additionally, tensile, flexural and charpy impact tests were performed. The characterizations revealed that the tururi fibrous tissue is composed of fibers of various diameters and has regions of bifurcation, indicating that the tissue can act in different ways when incorporated as reinforcement. The density, moisture content and weight had average values of 1.17 g/cm3, 16.58% and 146.61 g/m2, respectively. The thermal analysis revealed good thermal stability for the tururi fabric. The mechanical tests pointed out that as the incorporation of reinforcement occurred, the composites tested in traction had a loss of resistance, presenting a loss of 15MPa in relation to the matrix. When requested in flexion the composites reinforced with up to 2.5% showed better mechanical performance, with values of 63.9 MPa. The impact test revealed that the energy absorption capacity increased by 371% compared to the matrix, which indicates that the fabric acted as a good reinforcement agent.
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 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.
Desconhecido
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.
Desconhecido
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.
Desconhecido
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.
Desconhecido
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.
Desconhecido
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.
Desconhecido
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.

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