Berlin 2001 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 18: Poster: Polymer Blends, Heterogeneous Systems, Colloids and Nanoparticles, Interfaces, Polyelectrolytes
CPP 18.1: Poster
Mittwoch, 4. April 2001, 12:30–15:00, AT1
The Curing Process in the Epoxy Resin of DGEBA and DETA — •Thomas Britz1, Jan Kristian Krüger1, Bernd Valeske2, and Wulff Possart2 — 1Fachbereich 7.2 Experimentalphysik, Universtität des Saarlandes, Geb. 38, Postfach 151150, 66041 Saarbrücken — 2Fachbereich 8.15 Werkstoffwissenschaften und Fertigungstechnik, Universtät des Saarlandes, Geb. 22, Postfach 151150, 66041 Saarbrücken
We investigated the curing process of the epoxy resin with diglycidyl ether of bisphenol A (DGEBA) as prepolymer and diethylenetriamine (DETA) as curing agent for different mixture ratios by means of temperature modulated DSC, Brillouin and Raman scattering. The curing reaction is accompanied by a partly demixing of the educts resulting in small regions with a higher DETA concentration. In the cured epoxy resin these regions can be identified as bubblelike structures. Astonishingly, we could not distinguish their interior from the surrounding matrix in the cured resin by means of Raman scattering. This suggests, that the chemical composition is almost the same in the bubblelike structures as in the matrix. Furthermore the cured epoxy resin contains particles of crystalline DGEBA. The opto-acoustic dispersion function shows an anomalous behaviour during the curing process. It reaches a minimum at the time, when the refraction index begins to deviate from its linear increment and the cp(t)-curve has a inflexion point. We explain the minimum in the dispersion function by the arising of a second relaxator that is not related with the α-process. Reducing the thickness of the sample to 200nm, the glass temperature of the cured resin diminishes by approximately 75K compared with TG of the bulk.