Avaliação de diferentes modificações da atapulgita para aplicação no desenvolvimento de nanocompósitos de polietilenos
Data
2023-08-25
Autores
Silva, Thais Ferreira da 
Orientadores
Passador, Fabio Roberto
Tipo
Tese de doutorado
Título da Revista
ISSN da Revista
Título de Volume
Resumo
O desenvolvimento de embalagens é um dos setores mais importantes do segmento polimérico. O polietileno linear de baixa densidade (PELBD) e o polietileno de alta densidade (PEAD) são poliolefinas muito usadas nesse setor. Buscando a obtenção de embalagens segundarias rígidas cada vez mais resistentes e com propriedades diferenciadas adicionou- se a atapulgita (ATP) ao polímero, um argilomineral hidratado de magnésio e alumínio com morfologia microfibrosa. No entanto, dependendo da origem geológica, a ATP está associada à presença de minerais acessórios que precisam ser retirados para não interferirem em sua aplicação final. Dessa forma, realizou-se um processo de purificação da ATP natural (ATPn) por meio de separação física e tratamento químico, com peróxido de hidrogênio (H2O2) e ácido sulfúrico (H2SO4) obtendo-se a ATP purificada (ATPp). Visando uma melhor interação da ATP com as poliolefinas, foi realizada a modificação superficial da ATP por dois processos: silanização com adição de aminosilano (ATPs) e a organofilização com adição do cloridrato de trimetilamina (ATPo). As ATP foram caracterizadas quanto a composição química (espectroscopia de fluorescência de raios X - FRX) e mineralógica (difratometria de raios X - DRX), suas propriedades térmicas (análise termogravimétrica - TGA), morfológicas (microscopia eletrônica de varredura e de transmissão – MEV-FEG e MET), análise elementar (dos elementos carbono (C), hidrogênio (H), nitrogênio (N) e enxofre (S) – CHNS), e área superficial específica (método de Braunauer, Emmet e Teller - B.E.T.). Visando melhorar ainda mais a eficiência do reforço, foram utilizados os agentes compatibilizantes PELBD e PEAD enxertados com anidrido maleico (PELBD-g-MA e PEAD-g-MA) para a produção dos nanocompósitos. Dessa forma, a pesquisa foi direcionada na avaliação dos diferentes teores e tipos de modificações da ATP e no efeito da adição da ATP modificada e de agente compatibilizante nas poliolefinas. Nanocompósitos de PELBD/ATP e PEAD/ATP com diferentes teores e tipos de ATP (ATPn, ATPp, ATPs, ATPo) foram preparados pelo processo de extrusão seguido da prensagem a quente e caracterizados por ensaios mecânicos, térmicos, morfológicos e permeabilidade ao vapor de água. A adição de ATP modificada foi essencial para melhorar as propriedades dos nanocompósitos. Para ambas as matrizes poliolefínicas, o teor de 3% em massa de ATP foi o que apresentou a melhor performance. Os nanocompósitos mais promissores foram o PELBD/PELBD-g-MA/ATPs 3% e PEAD/PEAD-g-MA/ATPo 3%, evidenciando a importância do estudo na escolha da matriz, do uso do agente compatibilizante e das modificações superficiais no reforço utilizado.
The development of packaging is one of the most important sectors of the polymeric segment. Linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE) are polyolefins widely used in this sector. Seeking to obtain more and more resistant packages with different properties, attapulgite (ATP) was added to the polymer, a hydrated magnesium and aluminum clay mineral with a microfibrous morphology. However, depending on the geological origin, ATP is associated with the presence of accessory minerals that need to be removed so as not to interfere with its final application. Thus, a process of purification of natural ATP (ATPn) was carried out through physical separation and chemical treatment, with hydrogen peroxide (H2O2) and sulfuric acid (H2SO4), obtaining purified ATP (ATPp). Aiming at a better interaction of ATP with polyolefins, the surface modification of ATP was carried out by two processes: silanization with the addition of aminosilane (ATPs) and organophilization with the addition of an organic compound (ATPo). ATP were characterized in terms of chemical (X-ray fluorescence spectroscopy - FRX) and mineralogical (X-ray diffractometry - DRX) composition, thermal (thermogravimetric analysis - TGA), morphological (scanning and transmission electron microscopy - SEM- FEG and of TEM), elemental analysis (of the elements carbon (C), hydrogen (H), nitrogen (N) and sulfur (S) - CHNS), and specific surface area (method of Braunauer, Emmet and Teller - B.E.T.). To further improve the efficiency of reinforcement, compatibilizer agents PELBD and PEAD grafted with maleic anhydride (PELBD-g-MA and PEAD-g-MA) were used to produce nanocomposites. Thus, the research was directed towards evaluating the different levels and types of ATP modifications and the effect of adding modified ATP and a compatibilizer agent to polyolefins. LLDPE/ATP and HDPE/ATP nanocomposites with different levels and types of ATP (ATPn, ATPp, ATPs, and ATPo) were prepared by the extrusion process followed by hot pressing and characterized by mechanical, thermal, morphological and water vapor permeability tests. The addition of modified ATP was essential to improve the properties of the nanocomposites. For both polyolefin matrices, the content of 3 wt% of ATP showed the best performance. The most promising nanocomposites were PELBD/PELBD-g-MA/ATPs 3% and HDPE/PEAD-g-MA/ATPo 3%, evidencing the importance of the study in the choice of the matrix, the use of the compatibilizer agent and the surface modifications in the reinforcement used.
The development of packaging is one of the most important sectors of the polymeric segment. Linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE) are polyolefins widely used in this sector. Seeking to obtain more and more resistant packages with different properties, attapulgite (ATP) was added to the polymer, a hydrated magnesium and aluminum clay mineral with a microfibrous morphology. However, depending on the geological origin, ATP is associated with the presence of accessory minerals that need to be removed so as not to interfere with its final application. Thus, a process of purification of natural ATP (ATPn) was carried out through physical separation and chemical treatment, with hydrogen peroxide (H2O2) and sulfuric acid (H2SO4), obtaining purified ATP (ATPp). Aiming at a better interaction of ATP with polyolefins, the surface modification of ATP was carried out by two processes: silanization with the addition of aminosilane (ATPs) and organophilization with the addition of an organic compound (ATPo). ATP were characterized in terms of chemical (X-ray fluorescence spectroscopy - FRX) and mineralogical (X-ray diffractometry - DRX) composition, thermal (thermogravimetric analysis - TGA), morphological (scanning and transmission electron microscopy - SEM- FEG and of TEM), elemental analysis (of the elements carbon (C), hydrogen (H), nitrogen (N) and sulfur (S) - CHNS), and specific surface area (method of Braunauer, Emmet and Teller - B.E.T.). To further improve the efficiency of reinforcement, compatibilizer agents PELBD and PEAD grafted with maleic anhydride (PELBD-g-MA and PEAD-g-MA) were used to produce nanocomposites. Thus, the research was directed towards evaluating the different levels and types of ATP modifications and the effect of adding modified ATP and a compatibilizer agent to polyolefins. LLDPE/ATP and HDPE/ATP nanocomposites with different levels and types of ATP (ATPn, ATPp, ATPs, and ATPo) were prepared by the extrusion process followed by hot pressing and characterized by mechanical, thermal, morphological and water vapor permeability tests. The addition of modified ATP was essential to improve the properties of the nanocomposites. For both polyolefin matrices, the content of 3 wt% of ATP showed the best performance. The most promising nanocomposites were PELBD/PELBD-g-MA/ATPs 3% and HDPE/PEAD-g-MA/ATPo 3%, evidencing the importance of the study in the choice of the matrix, the use of the compatibilizer agent and the surface modifications in the reinforcement used.
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Citação
Silva, Thaís Ferreira Avaliação de diferentes modificações da atapulgita para aplicação no desenvolvimento de nanocompósitos de polietilenos/Thaís Ferreira da Silva – São José dos Campos, 2023. 195 f.