Otimização do processamento de partículas lead-free para aplicação em compósitos polímero/cerâmica com propriedades piezoelétrica e fotoluminescente

• Ano de defesa: 2015
• Autor(a) principal: Teixeira, Guilhermina Ferreira [UNESP]
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual Paulista (Unesp)
• Palavras-chave em Português: Anisotropia; Piezoeletricidade; Fotoluminescencia; Compositos polimericos; Ferroeletricidade; Polymeric composites
• Link de acesso: http://hdl.handle.net/11449/124539

The main goal of this research was improved the process for obtaining of NaNbO3 lead-free particles, in order to use the particles in flexible composites with piezoelectric and photoluminescence properties. By microwave-assisted hydrothermal synthesis, Na2Nb2O6.H2O fiber-like particles (a metaestable phase resulting from crystallization of NaNbO3) and NaNbO3 cubic-like particles were obtained. By thermal treatment, the Na2Nb2O6.H2O fiber-like particles were converted to NaNbO3 fiber-like particles, maintaining the anisotropic morphology of the Na2Nb2O6.H2O. After the characterization, the NaNbO3 fiber-like particles and cubic-like particles wich presented the best characteristics were chosen to be combined with PVDF to make composites. Knowing of good properties of materials obtained from anisotropic particles, and their influence in composites characteristics, a conductor polymer was inclused in composite composition. For this, the NaNbO3 fiber like particles were partially covered by PAni polymer in the state conductive. Using different volume fraction of NaNbO3 particles immersed in PVDF polimeric matrix, the composites were obtained by hot press. The results showed that the increasing of vome fraction of NaNbO3 improve the electric properties of materials, but reduced the flexibility. The anisotropic of the particles influenced positively in the electric and optical properties of composites. The composites obtained from NaNbO3 fiber-like presented better propperties tha composites obtained from NaNbO3 cubic-like particles. The PAni presence in the composites improved the electric properties, but reduced the photoluminescence emission. The composites obtained from anisotropic NaNbO3 without PAni were the materials that showed simultaneously the best combination of piezoelectric and photoluminescence properties. These composites can be used in piezophotonic devices.