INVESTIGADORES
ARANGUREN Mirta Ines
artículos
Título:
Curing Kinetics of Epoxy-Urethane Copolymers
Autor/es:
STEFANI, PABLO M.; MOSCHIAR, STELLA M.; ARANGUREN, MIRTA I.
Revista:
JOURNAL OF APPLIED POLYMER SCIENCE
Editorial:
Wiley
Referencias:
Lugar: ny; Año: 2001 vol. 79 p. 1771 - 1779
ISSN:
0021-8995
Resumen:
ABSTRACT: The cure of the epoxy resin diglycidyl ether of bisphenol A (Araldyt
GY9527) with a mixture of cycloaliphatic amines (Distraltec) was studied, and the focus
was on the effect of the copolymerization with a commercial polyurethane (PU) elastomer
(Desmocap 12). A simplified phenomenological model was proposed to represent
the copolymerization reaction. It considered the effect of the temperature and the
concentration of the elastomer on the reaction rate, and it was simple enough to be
included in models of processing conditions. A nonlinear regression analysis of the
experimental conversion data obtained from differential scanning calorimetry was
utilized to find the best fitting parameters to Kamals equation for the chemically
controlled part of the reaction (short times) under isothermal and constant heating-rate
conditions. The Rabinowitch approach together with the AddamGibbs theory was
utilized to introduce the effect of diffusion control at the end of the reaction on the
overall constant for the reaction rate. The Di Benedetto equation was used to predict
the conversion at which vitrification takes place for each run. Experimental results for
conversions higher than this critical conversion were utilized to obtain information
about the diffusion kinetic constant using a nonlinear regression analysis as previously.
The overall model obtained was used to calculate a calorimetric conversion and reaction
rate as functions of time, which was in excellent agreement with the experimental
results. The addition of PU elastomers affected the values of the activation energies of
the chemically and diffusion controlled parts of the reaction, as well as the final
conversion reached by the epoxyamine system. The proposed model allowed prediction
of all the observed features using parameters that were independent of the temperature
of the curing reaction. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 17711779, 2001
Key words: epoxyamine; modified epoxy resins; polyurethane modifiers; curing
kinetics; diffusion control