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Dielectric analysis as curing control for aminoplast resins—correlation with DMA

Dielektrische Analyse als Härtungskontrolle für Aminoplastharze – Korrelation mit DMA

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Abstract

Dielectric analysis (DEA) is a well-known method used for the monitoring of curing processes in non-aqueous radical or polyadditive systems. Tests on polycondensating binders used in wood-working industry show that the method is also suited for the curing characterization of aminoplast materials. As an evaluation of the test method, a correlation with dynamic mechanical analysis (DMA)—a conventional method for curing characterization—was carried out using simultaneous measurements. For thermally cross-linked urea-formaldehyde (UF) resins, ion viscosity measured by DEA is synchronously increasing with the storage modulus determined by DMA. Significantly, deceleration effects are detectable upon using latent ionic curing agents. Model free kinetics allows the calculation of isothermal values from dynamic measurements of logarithmic ion viscosity. The correlation tests provide a basis for DEA to be established as an in situ curing characterization method for aminoplast resin systems.

Zusammenfassung

Die dielektrische Analyse (DEA) ist im Bereich von nichtwässrigen radikalischen und polyadditiven Systemen eine bekannte Methode zur Verfolgung der Vernetzung. Versuche mit in der Holzwerkstoffindustrie verwendeten, polykondensierenden Bindemitteln zeigen, dass die Methode prinzipiell auch zur Verfolgung der Vernetzung von aminoplastischen Materialien geeignet wäre. In dieser Arbeit wurde zur Verifizierung der Messmethode eine Korrelation zur dynamisch-mechanischen Analyse (DMA), einer herkömmlichen Methode der Härtungscharakterisierung, durchgeführt. Die Messungen erfolgten in einer simultanen Messeinrichtung. Bei rein thermisch vernetzten Harnstoff-Formaldehyd (UF) Harzen verläuft der Anstieg der Ionenviskosität der DEA synchron mit dem Anstieg des Speichermoduls der DMA.

Bei Verwendung latenter ionischer Härter sind Verzögerungseffekte nachweisbar. Über eine modellfreie Kinetik ist es möglich, aus dynamischen Verläufen der logarithmierten Ionenviskosität isotherme Verläufe zu ermitteln. Die Korrelationstests stellen eine Basis für eine zukünftige in situ Härtungscharakterisierung aminoplastischer Leimsysteme über die DEA dar.

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Acknowledgements

The scientific work was financed by the COMET program. The authors would like to thank for the support of the Competence Center for Wood Composites and Wood Chemistry (Wood K plus—Kompetenzzentrum Holz GmbH, Linz, Austria). Further thanks to the Institute of Polymer Chemistry of Johannes Kepler University in Linz, and to Netzsch Gerätebau GmbH for providing of measurement instruments.

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  1. Kompetenzzentrum Holz GmbH, St.-Peter-Str. 25, 4021, Linz, Austria

    Claudia Pretschuh, Uwe Müller, Günter Wuzella, Florian Dorner & René Eckmann

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  1. Claudia Pretschuh
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  2. Uwe Müller
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  3. Günter Wuzella
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  4. Florian Dorner
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  5. René Eckmann
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Correspondence to Claudia Pretschuh.

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Pretschuh, C., Müller, U., Wuzella, G. et al. Dielectric analysis as curing control for aminoplast resins—correlation with DMA. Eur. J. Wood Prod. 70, 749–753 (2012). https://doi.org/10.1007/s00107-012-0612-0

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  • DOI: https://doi.org/10.1007/s00107-012-0612-0

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