• JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
 
  Bookmark and Share
 
 
Doctoral Thesis
DOI
10.11606/T.3.2007.tde-07012008-180133
Document
Author
Full name
Danilo Justino Carastan
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2007
Supervisor
Committee
Demarquette, Nicole Raymonde (President)
Gonçalves, Maria do Carmo
Kawano, Yoshio
Petri, Denise Freitas Siqueira
Valera, Ticiane Sanches
Title in Portuguese
Obtenção e caracterização reológica de nanocompósitos de polímeros estirênicos.
Keywords in Portuguese
Nanocompósitos
Polímeros
Reologia
Abstract in Portuguese
Neste trabalho foram preparados nanocompósitos de polímeros estirênicos com argilas organofílicas. Os polímeros estudados foram o poliestireno (PS), um copolímero tribloco de poliestireno-b-polibutadieno-b-estireno (SBS) e quatro copolímeros tribloco de poliestirenob- poli(etileno-co-butileno)-b-estireno (SEBS), sendo um deles modificado com anidrido maléico. Os nanocompósitos foram preparados por três técnicas de obtenção: mistura no fundido, solução e uma técnica híbrida que combina as duas primeiras. Os materiais obtidos foram caracterizados por difração de raios X (XRD), microscopia óptica (OM), microscopia eletrônica de transmissão (TEM), espalhamento de raios X a baixo ângulo (SAXS) e também foram realizados estudos reológicos através do ensaio de cisalhamento oscilatório de pequenas amplitudes (SAOS). O grau de dispersão de argila em algumas amostras foi avaliado por uma técnica baseada na análise de imagens obtidas por TEM. Os resultados mostraram que na maioria dos casos foram obtidos nanocompósitos intercalados, graças à presença da fase de PS em cada polímero. Amostras preparadas por solução tiveram o melhor grau de dispersão de argila, e o polímero que resultou na estrutura mais exfoliada foi o SEBS maleatado. Estudos reológicos mostraram-se muito sensíveis à formação de reticulados de partículas de argila nos nanocompósitos, que passaram a ter comportamento semelhante ao de sólidos. A combinação de técnicas de SAXS com reologia foi bastante útil para estudar a morfologia de fases ordenadas em copolímeros em bloco, permitindo identificar e distinguir estruturas lamelares, cilíndricas e esféricas em cada copolímero. Foi possível verificar que a presença de argila perturba a ordem das fases dos copolímeros e causa diferentes efeitos nas propriedades reológicas destes materiais.
Title in English
Preparation and rheological characterization of nanocomposites of styrenic polymers.
Keywords in English
Block copolymers
Clay
Nanocomposites
Polymers
Rheology
Abstract in English
In this work nanocomposites of styrenic polymers and organoclays were prepared. The polymers studied were polystyrene (PS), a polystyrene-b-polybutadiene-b-polystyrene triblock copolymer (SBS) and four polystyrene-b-poly(ethylene-co-butylene)-polystyrene triblock copolymers (SEBS), with one containing maleic anhydride. The nanocomposites were prepared using three different techniques: melt mixing, solution casting and a hybrid technique combining the former two. The materials obtained were characterized by x-ray diffraction (XRD), optical microscopy (OM), transmission electron microscopy (TEM), small angle x-ray scattering (SAXS) and by rheological studies, through small amplitude oscillatory shear tests (SAOS). The degree of clay dispersion was evaluated in some samples using a TEM image analysis technique. The results have shown that in most cases intercalated nanocomposites were obtained, due to the PS phase present in each polymer. Samples prepared by solution had the highest degree of clay dispersion, and the maleated SEBS was the polymer which originated the most exfoliated nanocomposite. The results have also shown that rheological studies are very sensitive to the formation of clay networks within the nanocomposites, which behave more solidlike. The combination of SAXS techniques and rheology was very useful to study the morphology of ordered phases in block copolymers, allowing to identify and distinguish the different structures of each copolymer, such as the lamellar, cylindrical and spherical phases. It was possible to verify that the presence of clay disturbs the phase order in the copolymers and has different effects on the rheological properties of these materials.
 
WARNING - Viewing this document is conditioned on your acceptance of the following terms of use:
This document is only for private use for research and teaching activities. Reproduction for commercial use is forbidden. This rights cover the whole data about this document as well as its contents. Any uses or copies of this document in whole or in part must include the author's name.
Publishing Date
2008-02-14
 
WARNING: Learn what derived works are clicking here.
All rights of the thesis/dissertation are from the authors
Centro de Informática de São Carlos
Digital Library of Theses and Dissertations of USP. Copyright © 2001-2020. All rights reserved.