Session: Advances in Mass Spectrometry:

Diglycidyl ether of bisphenol F (DGEBF) is frequently used as a component of epoxy resins and is often found in carbon fiber–reinforced composites. Understanding the degradation kinetics of DGEBF is important for understanding the thermal decomposition of composite materials employing DGEBF in a composite matrix. The most common method for determining degradation kinetics of polymer materials is thermogravimetric analysis combined with an isoconversional kinetic method. However, this technique can only monitor the apparent activation energy from a mass loss upon heating a material, leaving it blind to the individual underlying chemistries contributing to degradation. At Oak Ridge National Laboratory, evolved gas analysis–mass spectrometry (EGA-MS) was used to determine the kinetics of the individual chemistries that contribute to thermal degradation of DGEBF. Results from EGA-MS were compared to traditional thermogravimetric analysis results for both inert and oxidative atmospheres. Activation energies calculated from EGA-MS measurements were determined to be more accurate because the lower mass required by EGA-MS mitigates thermal diffusion effects. Finally, product specific kinetics were determined from the extracted ion thermograms in inert and oxidative environments. These product specific results reveal that under inert conditions the degradation kinetics of DGEBF resemble the formation kinetics of the bisphenol F fragments, whereas in oxidative conditions the degradation kinetics best align with those of xanthone fragment formation. In this presentation, experimental methodologies will be presented with a discussion of chemical degradation pathways and kinetics.

Douglas Duckworth

Appearances