Propriedades reológicas, térmicas e cinética de cristalização não isotérmica de blendas de polipropileno linear/polipropileno ramificado

• Ano de defesa: 2021
• Autor(a) principal: Macedo, Thatiana Cristina Pereira de
• Orientador(a): Ueki, Marcelo Massayoshi
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Programa de Pós-Graduação: Pós-Graduação em Ciência e Engenharia de Materiais
• Palavras-chave em Português: Ciência dos materiais; Polipropileno; Polímeros; Reologia; Ramificações; Blendas poliméricas; Propriedades reológicas; Propriedades térmicas; Cinética de cristalização não isotérmica
• Palavras-chave em Inglês: Polypropylene; Branched; Polymeric blends; Rheological properties; Thermal properties; Non-isothermal crystallization kinetics
• Área do conhecimento CNPq: ENGENHARIAS::ENGENHARIA ELETRICA::MATERIAIS ELETRICOS
• Link de acesso: https://ri.ufs.br/jspui/handle/riufs/15076

This work aimed to evaluate the rheological and thermal properties and nonisothermal crystallization kinetcs of blends of linear homopolymer polypropylene (PPH) and branched polypropylene (PPr). Two linear polypropylenes with different melt flow index were used: PPH301 with MFI=10 g/10min and PPH604 with MFI=1.5 g/10min (230°C e 2.16 Kg); and one branched polypropylene with MFI= 2 g/10min (230°C e 2.16 Kg). The rheological properties of the polymer blends were evaluated using the oscillatory, steady state and extensional dynamic mode. The analysis of the thermal conditions were investigated using DSC, using the Pseudo-Avrami/Jeziorny, Ozawa and Mo models in the analysis of non-isothermal crystallization kinetics; and Kissinger's model for analyzing the activation energy of crystallization. The rheology result show that the PPH301/PPr blends have an increase in viscosity, complex viscosity, storage modulus and loss proportional to the addition of PPr amount, while for the PPH604/PPr blends, it was observed higher influence of PPH604 on rheological properties, due to the greater entanglement of the branches in blends using polymers with similar melt indexes. The analysis of logarithmic additivity proposed by Utracki and the curves of Cole-Cole and Han, it was possible to conclude that the PPh/PPr blends are miscible, regardless of the MFI of the linear polypropylene. The addition of low PPr amount (10 wt %) the strain hardening behavior was observed in the extensional rheology tests of the studied polymer blends. From the results of thermal analysis, it was observed that the branches act as nucleating agents, resulting in an increase in the crystallization temperature of the branched polypropylene and polymer blends. The PseudoAvrami/Jeziorny and Mo models satisfactorily describe the non-isothermal crystallization kinetics of polypropylenes and PPh/PPr blends but the Ozawa model did not show a good fit between the experimental and theoretical results. The results of the activation energy obtained by the Kissinger model indicated that the addition of branches accelerates the polypropylene crystallization process. From the results, it is conclude that use of blends of linear polypropylene and branched polypropylene in processes that demand the combin