Full text
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| Author(s): |
Elisangela Moura Linares
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Química |
| Defense date: | 2009-09-18 |
| Examining board members: |
Fernando Galembeck;
Regina Celia Reis Nunes;
Edvaldo Sabadini
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| Advisor: | Fernando Galembeck |
| Abstract | |
This work shows the effect of ionic specie distribution on the morphology and on the mechanical properties of latex blend films, as well as it demonstrates the use of energy-filtered transmission electron microscopy (EFTEM) technique to morphological characterization of these blends and its clay nanocomposites, by exploring the low-loss electron energy region. Natural rubber (NR)/poly(styrenebutyl acrylate) [P(S-BA)] and NR/poly(vinyl chloride) [PVC] blends were investigated by scanning electric potential microscopy (SEPM). Using the electric potential maps, it has been observed ionic specie migration from one polymer phase towards the other, during blend preparation. The migration is spontaneous because it allows the reduction of system energy thanks to the decreasing of ionion electrostatic repulsion given by ion distribution throughout the phases. The migration is directed towards the polymer that has initially the lower charge concentration and that presents the higher dielectric constant. The domains formed by the two blend component present opposite charge signals, which contribute to compatibility enhancement through electrostatic adhesion. Low-energy-loss electron spectra show differences on molecular structure of polymers that form the blends. Such differences are expressed through contrast changing in low-energyloss images (molecular maps) acquired between 20 and 90 eV. NR/P(S-BA), P(SBA)/ PVC, P(S-BA)/poly(styrene-2-hydroxyethyl metacrylate) and their respective clay nanocomposites have been analyzed by EFTEM without staining and it revealed nano-sized domains, even when chemical composition was slightly different. Clay platelet distribution within nanocomposites was revealed due to contrast canceling of polymer domains on EFTEM images. (AU) | |