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Doctoral Thesis
DOI
https://doi.org/10.11606/T.3.2008.tde-29012009-142355
Document
Author
Full name
Márcio Yee
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2008
Supervisor
Committee
Demarquette, Nicole Raymonde (President)
Alcântara, Maria Regina
Macaúbas, Paulo Henrique Pierin
Rezende, Mirabel Cerqueira
Scuracchio, Carlos Henrique
Title in Portuguese
Estudo do comportamento reológico da mistura polimérica PMMA/PS compatibilizada ou não.
Keywords in Portuguese
Misturas poliméricas
PMMA/PS
Reologia
Tensão interfacial
Abstract in Portuguese
Neste trabalho, foi estudado o comportamento reológico nos regimes de viscoelasticidade linear (VEL) e não linear (VENL) da mistura polimérica de polimetacrilato de metila/poliestireno (PMMA/PS), compatibilizada ou não com os copolímeros: estatístico P(S-co-MMA) (VEL e VENL) e bloco P(S-b-MMA) (VEL). No estudo do comportamento de VEL, ensaios de cisalhamento oscilatório de pequenas amplitudes (COPA) foram realizados utilizando-se um reômetro de tensão controlada. O comportamento de VEL das misturas poliméricas foi comparado com os modelos teóricos de Bousmina[1] e generalizado de Palierne[2]. Os tempos de relaxação das misturas poliméricas foram obtidos analisando o comportamento reológico no regime de VEL utilizando o software desenvolvido por Honerkamp e Weese[3]. Os tempos obtidos foram comparados com o modelo de Jacobs et al.[4]. O estudo do comportamento de VENL foi conduzido através de ensaios de relaxação de tensão utilizando-se um reômetro de deformação controlada. Os resultados do comportamento reológico no regime de VEL indicaram a presença de quatro tempos de relaxação, para as blendas compatibilizadas com P(S-co- MMA) (composições menores de 10% de fase dispersa e concentrações maiores de 4% de copolímero): dois picos relacionados às fases puras; F, relacionado com a relaxação das gotas da fase dispersa e o relacionado com a relaxação do compatibilizante na interface entre as fases matriz e dispersa. Os valores experimentais de F e foram utilizados para os cálculos de tensão interfacial () e do módulo complexo de interface () das blendas poliméricas compatibilizadas. Os resultados indicaram uma diminuição de com o aumento da concentração de copolímero. Os resultados do comportamento reológico no regime de VEL, para as blendas compatibilizadas com P(S-b-MMA), também apresentaram a presença de quatro tempos de relaxação. Observou-se que o aumento da adição de P(S-b-MMA) proporcionou uma redução no .. Os resultados de VENL de relaxação de tensão mostraram a presença de três fenômenos de relaxação, relacionados com: 1) as fases puras, 2) a relaxação das gotas da fase dispersa e um terceiro mais rápido. A adição de P(S-co-MMA) resultou numa diminuição do processo de relaxação das gotas da fase dispersa.
Title in English
Rheological behavior of PMMA/PS polymer blends compatibilized or not.
Keywords in English
Interfacial tension
PMMA/PS
Polymer blends
Rheology
Abstract in English
In this work, the dynamic behavior of polymethylmetacrylate/polystyrene (PMMA/PS) blends to which P(S-co-MMA) was added was studied. Several blend composition and copolymer concentrations were studied. The rheological behavior of blends was compared to Bousminas[1] and Paliernes generalized[2] models. The relaxation spectra of the blends were also inferred, and the results were analyzed in light of the analysis of Jacobs et al.[4]. The relaxation spectra of the blends with smaller dispersed phase (below 10 wt%) and larger copolymer concentrations (above 0.4 wt%) showed the presence of four relaxation times, two corresponding to the blend phases, F, corresponding to the relaxation of the shape of the dispersed phase of the blend, and , that can be attributed to the relaxation of Marangoni stresses tangential to the interface between the dispersed phase and matrix. The experimental values of F and were used to infer the interfacial tension () and the interfacial complex shear modulus () for the different blends, decreased with increasing copolymer concentration. decreased with increasing blend dispersed phase concentration and decreasing copolymer concentration. The predictions of Paliernes generalized model were found to corroborate the experimental data once the values of and found analyzing the relaxation spectra were used in the calculations. Bousminas model was found to corroborate the data only for larger dispersed phase concentration. The stress relaxation behavior of PMMA/PS blends with or without random copolymer addition, submitted to step shear strain experiments in the linear and nonlinear regime was studied. The effect of blend composition, viscosity ratio and random copolymer was evaluated. All blends presented three relaxation stages, a first relaxation which was attributed to the relaxation of the pure phases, a second one which was characterized by the presence of plateau and a third fast one.
 
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Publishing Date
2009-02-06
 
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