The growth of macromolecules in reactive systems is associated with slowing down of the structural motions in a manner that closely resembles the effect of cooling or compressing glass-forming liquids. Depolarized photon correlation spectroscopy-which probes the molecular dynamics of a material via optical anisotropy fluctuations-has been used to monitor the reaction, at different temperatures, of three epoxy-amine formulations leading to network polymers via step-growth polymerization. The correlation function was fitted by the Kohlrausch-Williams-Watts form, and the parameters characterizing the structural relaxation process in the reactive mixtures were studied as a function of the extent of reaction, a quantity that was accurately measured by calorimetry. The behavior of the relaxation time successfully compares with a recently extended Adam-Gibbs entropy equation, derived from a connection between the reduction in configurations and the increase in number of chemical bonds during step polymerization.

Light scattering study of vitrification during the polymerization of model epoxy resins

COREZZI, Silvia
;
FIORETTO, Daniele;PUGLIA, Debora;KENNY, Jose Maria
2003

Abstract

The growth of macromolecules in reactive systems is associated with slowing down of the structural motions in a manner that closely resembles the effect of cooling or compressing glass-forming liquids. Depolarized photon correlation spectroscopy-which probes the molecular dynamics of a material via optical anisotropy fluctuations-has been used to monitor the reaction, at different temperatures, of three epoxy-amine formulations leading to network polymers via step-growth polymerization. The correlation function was fitted by the Kohlrausch-Williams-Watts form, and the parameters characterizing the structural relaxation process in the reactive mixtures were studied as a function of the extent of reaction, a quantity that was accurately measured by calorimetry. The behavior of the relaxation time successfully compares with a recently extended Adam-Gibbs entropy equation, derived from a connection between the reduction in configurations and the increase in number of chemical bonds during step polymerization.
2003
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11391/155114
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