The correlation between the glass transition temperature,T g , and the cure degree, α, of epoxy polymers has been analysed on the basis of an extension of the Vogel-Tamman-Fulcher equation for the viscosity of polymers and glasses. A physical meaning has been given to the coefficients of the series expansion of the functionT g=T g (α). This analysis allows one to verify that the experimental (T g ,α) data support the conclusion that, in the case of thermoset polymers, the ideal glass transition temperature,T o, appearing in the VTF equation, is larger thanT g . This conclusion may be supported by the thermodynamic interpretation ofT 0 as the temperature at which the excess entropy of the systems tends to vanish: in the case of partially cured thermosets;T 0 would represent the minimum temperature at which the system becomes able to enhance its cure degree.

Epoxy polymers : Glass transition/cure degree correlation / A. Schiraldi, P. Baldini, E. Pezzati. - In: JOURNAL OF THERMAL ANALYSIS. - ISSN 0368-4466. - 30:6(1985 Nov), pp. 1343-1348.

Epoxy polymers : Glass transition/cure degree correlation

A. Schiraldi
Primo
;
1985

Abstract

The correlation between the glass transition temperature,T g , and the cure degree, α, of epoxy polymers has been analysed on the basis of an extension of the Vogel-Tamman-Fulcher equation for the viscosity of polymers and glasses. A physical meaning has been given to the coefficients of the series expansion of the functionT g=T g (α). This analysis allows one to verify that the experimental (T g ,α) data support the conclusion that, in the case of thermoset polymers, the ideal glass transition temperature,T o, appearing in the VTF equation, is larger thanT g . This conclusion may be supported by the thermodynamic interpretation ofT 0 as the temperature at which the excess entropy of the systems tends to vanish: in the case of partially cured thermosets;T 0 would represent the minimum temperature at which the system becomes able to enhance its cure degree.
Die Korrelation zwischen der Glasumwandlungs-temperaturT g und dem Aushärtungsgrad α von Epoxidpolymeren wurde analysiert, und zwar basierend auf einer Erweiterung der Vogel-Tamman-Fulcher-Gleichung für die Viskosität von Polymeren und Gläsern. Den bei der Reihenentwicklung der FunktionT g =T g (α) auftretenden Koeffizienten wurde eine physikalische Bedeutung zugeschrieben. Diese Analyse ermöglicht nachzuweisen, daß die experimentellen Daten (T g ),α die Schlußfolgerung stützen, daß im Falle von hitzehärtbaren Polymeren die in der VTF-Gleichung auftretende sogenannte ideale GlasumwandlungstemperaturT 0 höher alsT g ist. Diese Konklusion wird auch durch die thermodynamische Interpretation vonT 0 gestützt, nämlich als die Temperatur, bei der die Überschußentropie des Systems gegen Null geht: im Falle von teilweise ausgehärteten hitzehärtbaren Polymeren würdeT 0 die minimale Temperatur darstellen, bei der eine Erhöhung des Aushärtungsgrades des Systems einsetzt.
epoxy polymers ; glass transition ; cure degree
Settore CHIM/02 - Chimica Fisica
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/190218
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