Analyzing the Effect of Thermal Ramp Rate on Epoxy Network Formation During Cure Using Real Time Infrared Spectroscopy
Full understanding of network formation in an epoxy/diamine matrix has previously not been achieved due to a limitation in directly studying the creation and consumption of secondary amine during cure. In this work, the development of epoxy/diamine networks was monitored, in real time, throughout cure with Fourier Transform Infrared Spectroscopy in the near infrared region (NIR) and the effect of ramp rate studied. Networks were heated at slow and rapid ramp rates and held at 180 °C for 2 hours with functional group consumption monitored throughout. Networks cured with difunctional or tetrafunctional epoxy monomers were also compared in order to determine the effect of chemical gelation on final network formation. Molar absorptivity was determined to be dependent on temperature and was adjusted during analysis to allow for more representative results of functional group consumption and overall network conversion. The accuracy of this method to measure network conversion was validated using dynamic scanning calorimetry. This work establishes a means to view a complete picture of the development of epoxy-amine networks throughout cure, which allows for a more complete understanding of the effect of cure protocol on final network structure.
Author: Andrew Janisse
Conference: SAMPE Seattle 2017