Síntese e caracterização de polímeros parcialmente fluorados (PVDF) como materiais porosos

• Ano de defesa: 2023
• Autor(a) principal: Rolon, Natasha Villa
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso embargado
• Idioma: por
• Instituição de defesa: Universidade Federal da Grande Dourados; Brasil; Faculdade de Ciências Exatas e Tecnologia; Programa de pós-graduação em Ciências e Tecnologia Ambiental; UFGD
• Palavras-chave em Português: Prensagem a quente; Método casting; Tecnologia ambiental; Hot pressing; Casting method; Environmental technology; CNPQ::CIENCIAS EXATAS E DA TERRA
• Link de acesso: http://repositorio.ufgd.edu.br/jspui/handle/prefix/5630

Fluoropolymers are a unique class of materials with several interesting properties due to their chemical structures formed by strong carbon-carbon and carbon-fluorine bonds. With various application areas, from membrane distillation, smart sensors and tissue engineering to the biomedical field. In this sense, the present work aimed to synthesize and characterize porous polymers of partially fluorinated PVDF, through different delivery routes. Polyvinylidene Kynar® Fluoride, Sodium Chloride (NaCl) and Corn Starch were used to prepare films and membranes. The starch-doped PVDF films were synthesized by the casting method, while the NaCl-doped films were obtained by the hot pressing method, both films underwent a washing process after obtaining, and the PVDF membranes were synthesized by the casting method. and immersed in deionized water. After synthesizing the optical characterizations of FTIR and UV-vis, thermal characterization of DSC and TG, analyzes were carried out to verify the porosity of the material by density and SEM. Through characterization by FTIR, we observed a greater amount of peaks characteristic of the α phase, with no significant difference for both films and membranes. Through the calculation of the β phase, the presented values were relatively low, varying between 42.80% and 45.50%. The membranes adhered by the casting method showed visible characteristics of porosity and were confirmed by scanning electron microscopy (SEM) and the decrease in density. In the films obtained by the mechanical route with the use of the NaCl material, the satisfaction was favorable, they presented porosity in the material after the washing process. For the films obtained by the starch-doped casting method, there were some pores in the samples, however, the interaction of PVDF and starch in the formation of a blend was observed. It was observed that the properties of PVDF prevailed, according to the characterizations performed. Through the UV-vis results, the sharpest peaks after 215 nm and close to 220 nm may be correlated with the electronic transition in fluorocarbons (F-C), a characteristic factor of PVDF. The direct bandgap was obtained by UV-vis analysis, around 5.22 to 5.81 eV and indirect bandgap between 2.62 and 4.54 eV. It is possible to observe a significant decrease of 30% in the indirect bandgap of PVDF/Starch 10% and 10% washed. For washed PVDF/NaCl 10% and PVDF/NaCl 10% films, there was a variation of approximately 39% in indirect bandgap, a factor resulting from the presence of unstructured volume defects. Considering the significant variation in the curves of the DSC/TG graphs, the crystallization point is observed around 156°C and from 420°C, the beginning of material degradation. Finally, the results reveal that the different obtaining routes showed porosity after the washing process, being potential candidates for applications in the food industry and in filtering systems.