Abstract
Methods were developed for calculating reaction activation energies from dielectric property measurements during isothermal and nonisothermal cure of thermosetting polymers. These methods were derived by assuming that features of the dielectric response occurred at unique extent of reaction values. Activation energy results were obtained through dielectric analysis for two thermosetting resin systems: a model epoxy system — tetraglycidyl-4, 4′-diaminodiphenylmethane cured with 25 parts per hundred of 4,4′-diaminiphenylsulfone hardener; and a model dicyanate blend resin, 55% (by weight) of bisphenol A dicyanate and 45% of tetrao-methyl bisphenol F dicyanate. Results were in excellent agreement with activation energies determined from differential scanning calorimetry measurements.
Zusammenfassung
Es wurden Verfahren zur Berechnung der Aktivierungsenergien aus dielektrischen Messungen der isothermen bzw. nichtisothermen Aushärtung von Duroplasten entwickelt. Dabei wurde angenommen, daß die dielektrische Antwort bei einem einzelnen Wert der Reaktionswerte erfolgt. Die Aktivierungsenergie-Ergebnisse wurden für zwei Duroplast-Harze ermittelt: ein Epoxysystem — Tetraglycidyl-4,4′-diamonidiphenylmethan, gehärtet mit 25% 4,4′-Diaminodiphenylsulfonhärter; und ein Dicyanatmischharz aus 55 Gew.% Bisphenol A Dicyanat und aus 45 Gew.% Tetra-o-methylbisphenol F Dicyanat. Die Ergebnisse stehen in guter Übereinstimmung mit den aus DSC-Messungen erhaltenen Werten.
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References
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The authors would like to thank Dr. M. A. Bachmann of ICI, Dr. R. B. Prime of IBM, and Dr. E. M. Woo of the Polymeric Composites Laboratory and currently with Boeing Commercial Airplane Group, for helpful discussions in the development of this technique. In addition, the expert coordination for the project provided by Ms. Louise Peterson and Dr. Kyujong Ahn, as well as Shangying Zeng in analyzing the dicyanate data at the Polymeric Composites Laboratory, is gratefully acknowledged. Equipment support for this project was provided by Tetrahedron Associates and TA Instruments (formerly DuPont Instruments), through their participation at the Polymeric Composites Laboratory consortium at the University of Washington. Financial assistance for this work was provided by ICI, and the National Science Foundation Grant # MSM 8352414.
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Nass, K.A., Seferis, J.C. Activation energy determinations from dielectric thermal analysis of reacting polymeric systems. Journal of Thermal Analysis 37, 2407–2421 (1991). https://doi.org/10.1007/BF01913743
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DOI: https://doi.org/10.1007/BF01913743