Untitled in english

Author(s)

Augusto Teruo Morita

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Escola Politécnica (EP/BC)
• Defense date: 2002-09-10

Examining board members

Nicole Raymonde Demarquette; Elias Hage Junior

• Advisor: Nicole Raymonde Demarquette

Abstract

The properties of polymer blends, including ternary blends, are strongly influenced by their morphology. Therefore, the knowledge and prediction of morphology of polymer blend after processing step is necessary. In this work, ternary blends of PMMA/PP/PS were processed in a internal mixer and their morphology were observed by scanning electron microscopy. The observed morphologies were compared to the morphologies predicted by thermodynamics theories (spreading coefficient theory and minimal surface free energy theory). These theories predict the type of morphology for ternary blends as a function of interfacial tension between the components of the blend. In this work, the interfacial tension values were evaluated by rheological and static methods. The equilibrium morphologies predicted by thermodynamics theories were compared to the experimental morphologies evaluated by scanning electron microscopy. The major part of experimental morphologies observed corroborated the morphologies predicted by the minimal surface free energy theory. The morphology type was shown to be basically dependent on the polymer matrix. It was observed that the spreading coefficient theory couldn\'t predict the major part of observed morphologies. One possible reason for this discrepancy between experimental behaviour and theory was that the values of interfacial tension led to spreading coefficient values close to zero and in some cases spreading coefficient values were lower than the experimental error, leading to incorrect predictions of the morphology of ternary blends. In order to evaluate the influence of viscosity of PMMA, two differentes types of PMMA with different viscosities were studied. It was observed that the viscosity of PMMA didn\'t influence the type of morphology. Great differences were not observed as far as quantitative analysis was analysed. The evolution of morphology was evaluated as a function of time. It was observed that the evolution process of morphology occurs principally in the first stages of mixture process. (AU)