Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/80143
Type: Artigo de periódico
Title: Relationship between pore structure and H-1-NMR relaxation times in TiO2/poly(dimethylsiloxane) and CaCO3/poly(dimethylsiloxane) composite powders
Author: Vichi, FM
Galembeck, F
Halstead, TK
Williams, MAK
Abstract: Titanium(IV) oxide/polydimethylsiloxane (PDMS) and calcium carbonate/ PDMS composite powders were obtained by adsorption of the polymer from a chloroform solution onto the inorganic particles followed by a thermal treatment. The composites were characterized by H-1-NMR relaxation and porosimetry. The composites present shorter spin-lattice (T-1) and spin-spin (T-2) proton relaxation times than silica-reinforced PDMS, and the activation energies for the motions that cause spin-lattice relaxation are 5.8, 4.9, and 0.72 kJ mol(-1) for TiO2/PDMS, CaCO3/PDMS, and neat PDMS, respectively, revealing the greater rigidity of the polymer chains within the composite. Spin-spin relaxation (T-2) measurements of the composites showed a major component with a shorter T-2 and a minor component with a longer T-2. The intensity ratio of these two components is very close to the ratio between the amount of polymer that remains between the particles and that penetrating the particle pores as measured by Hg intrusion porosimetry. The shorter T-2 component was thus assigned to polymer interspersed among the particles, while the longer T-2 component was assigned to polymer within the particle pores. (C) 1999 John Wiley & Sons, Inc.
Subject: polydimethylsiloxane/inorganic powder composites
proton NMR relaxation
porosity
Country: EUA
Editor: John Wiley & Sons Inc
Rights: fechado
Identifier DOI: 10.1002/(SICI)1097-4628(19991209)74:11<2660
Date Issue: 1999
Appears in Collections:Unicamp - Artigos e Outros Documentos

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