Caracteriza??o do processo de gelifica??o de solu??es quitosana utilizando reometria e espalhamento din?mico da luz

• Main Author: Morais, Wildson Arcanjo de
• Other Authors: CPF:90623207753
• Format: Others
• Language: Portuguese
• Published: Universidade Federal do Rio Grande do Norte 2014
• Subjects: Espalhamento din?mico da luz; Quitosana; Tempo de gelifica??o.; Dynamic light scattering; Chitosan; Gelation time.; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA
• Online Access: http://repositorio.ufrn.br:8080/jspui/handle/123456789/17649

Made available in DSpace on 2014-12-17T15:41:55Z (GMT). No. of bitstreams: 1 WildsonAM_DISSERTPPGQ.pdf: 2126383 bytes, checksum: 6a1a9e8b2c55caac2fbd3fb938bff756 (MD5) Previous issue date: 2011-07-20 === Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior === Gels consist of soft materials with vast use in several activities, such as in pharmaceutical industry, food science, and coatings/textile applications. In order to obtain these materials, the process of gelification, that can be physical (based on physical interactions) and/or chemical (based on covalent crosslinking), has to be carried out. In this work we used dynamic light scattering (DLS) and rheometry to monitor the covalent gelification of chitosan solutions by glutaraldehyde. Intensity correlation function (ICF) data was obtained from DLS and the exponential stretched Kohrausch-William-Watts function (KWW) was fitted to them. The parameters of the KWW equation, β, Γ and C were evaluated. These methods were effective in clarifying the process of sol-gel transition, with the emergence of non-ergodicity, and determining the range of gelation observed in about 10-20 minutes. The dependence between apparent viscosity on reaction time was used to support the discussion proposed. === G?is s?o materiais que possuem aplica??es em v?rias ?reas, tais quais, na ind?stria de tintas, alimentos e farmac?utica. Os m?todos empregados para obten??o dos g?is podem ser f?sicos (intera??es f?sicas) e/ou qu?micos (baseado em intera??es covalentes), tal processo, ? denominado gelifica??o. Neste trabalho, o processo de gelifica??o de quitosana/glutaralde?do foi monitorado utilizando reometria e espalhamento da luz (DLS). As fun??es de correla??o de intensidade (ICF) foram obtidas atrav?s de DLS e a equa??o de Kohrausch-William-Watts (KWW) foi ajustada com os dados experimentais. Os par?metros da equa??o KWW, β, Γ e C foram avaliados. Estes m?todos foram eficazes na clarifica??o do processo que compreende a transi??o sol-gel, com o surgimento da n?o-ergodicidade, e na determina??o da faixa de gelifica??o, observada em torno de 10-20 minutos. A depend?ncia da viscosidade aparente em fun??o do tempo foi utilizada para comprovar o tempo de gelifica??o observado no DLS.