Fechar
Metadados

@PhDThesis{Santos:2017:SíCaHí,
               author = "Santos, Ester Pinheiro dos",
                title = "S{\'{\i}}ntese e caracteriza{\c{c}}{\~a}o de h{\'{\i}}bridos 
                         celul{\'o}sicos modificados com {\'o}xidos met{\'a}licos 
                         hidratados para aplica{\c{c}}{\~a}o como aditivos em espumas 
                         r{\'{\i}}gidas de poliuretano",
               school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
                 year = "2017",
              address = "S{\~a}o Jos{\'e} dos Campos",
                month = "2017-06-23",
             keywords = "celulose, {\'o}xidos met{\'a}licos hidratados, h{\'{\i}}bridos 
                         org{\^a}nico-inorg{\^a}nico, poliuretano, comp{\'o}sitos, 
                         cellulose, hydrous metallic oxide, organic-inorganic hybriids, 
                         polyurethane, composites.",
             abstract = "O sinergismo de propriedades entre diferentes componentes em um 
                         {\'u}nico material torna-se cada vez mais atrativo, no que se 
                         refere {\`a} diversidade de aplica{\c{c}}{\~o}es assim como na 
                         utiliza{\c{c}}{\~a}o de subprodutos agroindustriais. Al{\'e}m 
                         disso, a busca por fontes renov{\'a}veis aliada {\`a} elevada 
                         disponibilidade evidenciam as fibras lignocelul{\'o}sicas como 
                         precursoras no desenvolvimento de novos materiais. Os 
                         h{\'{\i}}bridos org{\^a}nico-inorg{\^a}nicos apresentamse 
                         promissores, podendo ser aplicados em v{\'a}rios setores, tais 
                         como cat{\'a}lise, adsor{\c{c}}{\~a}o e como aditivos em 
                         matrizes polim{\'e}ricas para a produ{\c{c}}{\~a}o de membranas 
                         e comp{\'o}sitos. A proposta deste trabalho {\'e} desenvolver e 
                         caracterizar h{\'{\i}}bridos, provenientes da 
                         combina{\c{c}}{\~a}o entre a celulose da folha de bananeira e os 
                         {\'o}xidos met{\'a}licos hidratados de ni{\'o}bio 
                         (Nb\$_{2}\$O\$_{5}\$.nH\$_{2}\$O), de alum{\'{\i}}nio 
                         (Al\$_{2}\$O\$_{3}\$.nH\$_{2}\$O) e de zinco 
                         (ZnO.nH\$_{2}\$O), visando a produ{\c{c}}{\~a}o de espumas 
                         r{\'{\i}}gidas de poliuretano e verificar o efeito destes 
                         aditivos h{\'{\i}}bridos e seus precursores nas propriedades 
                         t{\'e}rmicas e mec{\^a}nicas dos comp{\'o}sitos. Inicialmente, 
                         as folhas de bananeira foram submetidas a diferentes tratamentos 
                         qu{\'{\i}}micos, a fim de avaliar a modifica{\c{c}}{\~a}o mais 
                         eficiente para o isolamento da celulose. Posteriormente, os 
                         h{\'{\i}}bridos foram sintetizados via precipita{\c{c}}{\~a}o 
                         convencional e um estudo de propor{\c{c}}{\~a}o foi realizado, 
                         com diferentes rela{\c{c}}{\~o}es m{\'a}ssicas entre a celulose 
                         e os {\'o}xidos met{\'a}licos hidratados. O estabelecimento da 
                         melhor propor{\c{c}}{\~a}o de cada aditivo h{\'{\i}}brido foi 
                         determinado por termogravimetria. Os h{\'{\i}}bridos escolhidos 
                         foram caracterizados por testes de absor{\c{c}}{\~a}o de 
                         {\'a}gua, DSC, FTIR, DRX, MEV/EDX e, em seguida, incorporados 
                         {\`a} matriz de poliuretano para a s{\'{\i}}ntese das espumas 
                         r{\'{\i}}gidas. Os comp{\'o}sitos foram obtidos mediante a 
                         adi{\c{c}}{\~a}o de 1 a 5 \% m/m dos h{\'{\i}}bridos 
                         escolhidos, al{\'e}m dos respectivos precursores (celulose e 
                         {\'o}xidos met{\'a}licos hidratados), e caracterizados por TGA, 
                         DSC e ensaio de compress{\~a}o. Os resultados de termogravimetria 
                         indicaram as propor{\c{c}}{\~o}es 
                         97Celfb/3Nb\$_{2}\$O\$_{5}\$.nH\$_{2}\$O, 
                         94Celfb/6Al\$_{2}\$O\$_{3}\$.nH\$_{2}\$O e 97Celfb/3ZnO.nH2O 
                         como as melhores rela{\c{c}}{\~o}es celulose/{\'o}xido 
                         (h{\'{\i}}bridos). As curvas DSC exibiram o efeito da 
                         fra{\c{c}}{\~a}o inorg{\^a}nica na supress{\~a}o de calor, 
                         evidenciando os h{\'{\i}}bridos 
                         97Celfb/3Nb\$_{2}\$O\$_{5}\$.nH\$_{2}\$O e 
                         94Celfb/6Al\$_{2}\$O\$_{3}\$.nH\$_{2}\$O com propriedades em 
                         potencial para atuarem como retardantes de chamas. As 
                         an{\'a}lises de EDX confirmaram a incorpora{\c{c}}{\~a}o dos 
                         metais na matriz celul{\'o}sica, corroborando com os resultados 
                         de DRX e FTIR. Nos testes de absor{\c{c}}{\~a}o de {\'a}gua o 
                         h{\'{\i}}brido 94Celfb/6Al\$_{2}\$O\$_{3}\$.nH\$_{2}\$O 
                         apresentou a maior redu{\c{c}}{\~a}o no car{\'a}ter 
                         hidrof{\'{\i}}lico, comparado {\`a} celulose isolada e aos 
                         demais h{\'{\i}}bridos, o que nos induz a esperar por um aditivo 
                         que proporcione aumento de ades{\~a}o na interface fibra/matriz 
                         polim{\'e}rica, resultando em melhores propriedades t{\'e}rmicas 
                         e mec{\^a}nicas. Os resultados t{\'e}rmicos e mec{\^a}nicos 
                         evidenciaram o h{\'{\i}}brido 
                         94Celfb/6Al\$_{2}\$O\$_{3}\$.nH\$_{2}\$O como o melhor 
                         aditivo na formula{\c{c}}{\~a}o para o comp{\'o}sito PU + 1\% 
                         m/m 94Celfb/6Al\$_{2}\$O\$_{3}\$.nH\$_{2}\$O. ABSTRACT: The 
                         synergism properties between different components in an unique 
                         material become increasingly attractive, as regards the variety of 
                         applications like the use of agro industrial by-products. 
                         Furthermore, the search for renewable sources combined with high 
                         availability evidence the lignocellulosic fibers as precursor in 
                         the development of new materials. Organic-inorganic hybrids have 
                         to be promising and can be applied in several sectors, such as 
                         catalysis, adsorption and as additives in polymer matrices in the 
                         production of membranes and composites. The purpose of this work 
                         is to develop and characterize hybrids derived from the 
                         combination between the cellulose of leaf bananas plant and 
                         hydrous metallic oxides of niobium (Nb2O5.nH2O), aluminum 
                         (Al2O3.nH2O) and zinc (ZnO.nH2O), aiming at the production of 
                         rigid polyurethane foams and to verify the effect of these 
                         additives hybrid and their precursors on the thermal and 
                         mechanical properties of the composites. Initially, the banana 
                         leaves were submitted to different chemical treatments, in order 
                         to evaluate the most efficient modification for isolation of 
                         cellulose. After, the hybrids were synthesized through 
                         conventional precipitation and a proportion study was performed, 
                         with different mass relations between the cellulose and the 
                         hydrous metallic oxides. The establishment of the best proportion 
                         of each additive hybrid was determined by thermogravimetric 
                         analysis. The selected hybrids were characterized by water 
                         absorption tests, DSC, FTIR, DRX, MEV/EDX and then incorporated 
                         into the polyurethane matrix for the synthesis of rigid foams. The 
                         composites were obtained by adding 1 to 5 % m/m of the chosen 
                         hybrids, beyond to the respective precursors (cellulose and 
                         hydrous metallic oxides) and characterized by TGA, DSC and 
                         compression test. The results of thermogravimetric analysis 
                         indicated the proportions 97Celfb/3Nb2O5.nH2O, 94Celfb/6Al2O3.nH2O 
                         and 97Celfb/3ZnO.nH2O as the best cellulose/oxide ratios 
                         (hybrids). DSC curves exhibited the effect of oxides on heat 
                         suppression, evidencing the hybrids 97Celfb/3Nb2O5.nH2O and 
                         94Celfb/6Al2O3.nH2O with potential properties to act as flame 
                         retardants. EDX analyzes confirmed the incorporation of the metals 
                         in the cellulosic matrix, corroborating with the results of XRD 
                         and FTIR. In the tests of water absorption, the hybrid 
                         94Celfb/6Al2O3.nH2O presented the greatest reduction in 
                         hydrophilic character, compared to the isolated cellulose and the 
                         other hybrids, which induces us to wait for an additive that 
                         provides increased adhesion at the fiber/polymeric matrix 
                         interface, resulting in better thermal and mechanical properties. 
                         The thermal and mechanical results show the hybrid 
                         94Celfb/6Al2O3.nH2O as the best additive in the formulation for 
                         the composite PU + 1% m/m 94Celfb/6Al2O3.nH2O.",
            committee = "Nono, Maria do Carmo de Andrade (presidente/orientadora) and 
                         Silva, Maria L{\'u}cia Caetano Pinto da (orientadora) and 
                         Machado, Jo{\~a}o Paulo Barros and Soares Neto, Turibio Gomes and 
                         Pardini, Luiz Claudio and Ancelotti Junior, Antonio Carlos",
         englishtitle = "Synthesis and characterization of cellulosic hybrids modified with 
                         hydrous metallic oxides for application as additives in rigid 
                         polyurethane foams",
             language = "pt",
                pages = "247",
                  ibi = "8JMKD3MGP3W34P/3PAKJLH",
                  url = "http://urlib.net/rep/8JMKD3MGP3W34P/3PAKJLH",
           targetfile = "publicacao.pdf",
        urlaccessdate = "05 dez. 2020"
}


Fechar