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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Navegando Programa de Pós-Graduação em Ciência e Engenharia de Materiais - PPGCEM/Ananindeua por Orientadores "MAIA, Ana Áurea Barreto"
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Item 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/0000-0002-1880-1442The 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.Item 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/0000-0002-1880-1442This 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.Item 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/0000-0002-1880-1442The 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.