Berlin 2001 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 18: Poster: Polymer Blends, Heterogeneous Systems, Colloids and Nanoparticles, Interfaces, Polyelectrolytes

CPP 18.2: Poster

Wednesday, April 4, 2001, 12:30–15:00, AT1

Comparative study of curing behavior of epoxy resin with rheological and ultrasonic methods — •Jarlath McHugh, Joachim Döring, and Wolfgang Stark — Bundesanstalt fuer Materialforschung und -pruefung, 12205 Berlin, Unter den Eichen 87, Germany

By measuring the ultrasonic sound velocity and the attenuation it is possible to monitor the curing process. From the literature there remain uncertainties on the sensitivity of ultrasound to the critical transformations in epoxy resin cure: gelation and vitrification. A commercial high temperature epoxy amine resin (tradename RTM6, used in aircraft industry) was chosen.

Isothermal cure temperatures between 120 to 180 C following experiments were performed:

Ultrasonic measurements in through transmission, parallel plate rheometer to determine time to gelation, DSC in combination with a kinetic model to establish time to vitrification.

Results: The ultrasound results indicate that a relaxation region is passed through during cure. The peak in attenuation could easily be mistaken for gelation as it coincides with gelation at 160 C which is the recommended processing temperature. At other temperatures 120 C and 180 C the peak in ultrasonic attenuation is observed before and after gelation respectively. The peak in attenuation and the form of the sound velocity profile is actually caused by vitrification being observed earlier at 4 MHz.