Morfologia de ionômero E/MMA-Na+ proposta por técnicas termo-ópticas

• Ano de defesa: 2017
• Autor(a) principal: Gomez Higuita, German Dario
• Orientador(a): Canevarolo Júnior, Sebastião Vicente
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Carlos; Câmpus São Carlos
• Programa de Pós-Graduação: Programa de Pós-Graduação em Ciência e Engenharia de Materiais - PPGCEM
• Palavras-chave em Português: Ionômeros; Transformações morfológicas; Relaxação; Reordenamento
• Palavras-chave em Inglês: Ionomers; Morphological transformations; Relaxation; Reordering
• Área do conhecimento CNPq: ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA::MATERIAIS NAO METALICOS
• Link de acesso: https://repositorio.ufscar.br/handle/ufscar/9564

The DSC low temperature endothermic peak shown by sodium neutralized poly(ethylene-random-methacrylic acid) (E/MAA) ionomers has been shown here to be the result of two different and dependent morphological transformations, i.e. relaxation of the ionic aggregates and molecular reordering of ethylene chain segments. These two events could be separated by applying a hydrothermal treatment that swells the ionic clusters and allows the thickening the secondary PE crystals. Water plasticizes the ionic aggregates, shifting his glass transition temperature downwards. On the other hand the endothermic peak due to the molecular reordering of the thicker secondary crystals independently shifts upwards. The relaxation of the ionic aggregates was detected either by static (DSC) or dynamic (DMTA) thermal analysis. The reordering of ethylene segments were observed optically following the cross-polarized transmitted light intensity and by X-Ray diffraction pattern. Both, primary and secondary PE crystals, after either dry or wet thermal annealing improve the PE chains packing by expelling out the non-crystallizable methacrylic comonomer mers.