Resin Cure Kinetics and Exploring the Possibilities of Material Degradation

• Elizabeth Rock, Chemical Engineering, University of Delaware

• Thomas Cender, Center for Composite Materials, University of Delaware
• Steve Sauerbrunn, Center for Composite Materials, University of Delaware

Thermosetting resins are polymers that are irreversibly hardened once cured and are stable at high temperatures. Increasing temperature will induce the resin’s curing process. The purpose of this research is to develop an equation that can model the curing process and exclude degradation which occurs during a dynamic heating test. First, multiple DSC (Differential Scanning Calorimeter) scans were run at different temperature ramp rates. A DSC measures the sample’s heat flow as a function of temperature and time. Data collected for an epoxy resin showed two peaks, which could indicate a second reaction other than curing is happening. Varying discoloration was observed at the end of the runs. These two observations suggest that the test method is inducing material degradation. Material degradation is the reduction of the polymer’s physical properties such as weight loss and strength. To create a strong kinetics model, the possibility of degradation must be addressed. To further investigate this issue, multiple tests were conducted using an instrument which combines a hotstage microscope and DSC. The microscope captures images of the sample during its DSC run and compiles them into a movie. The movie helps to identify when discoloration begins and any other observations worth noting while the sample cures. The method being developed will be able to correlate sample color (due to degradation) to the heat flux observed in the degradation reaction. The results will allow a more precise determination of the epoxy’s heat of reaction.