Measurement of kinetics and thermodynamics of the thermal degradation for charring polymers

This work was focused on developing and applying a systematic methodology for the measurement of kinetics and thermodynamics of the thermal degradation of polymeric materials. This methodology employed a simultaneous thermal analysis instrument capable of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). A numerical model was utilized to fit thermogravimetric data to obtain thermal degradation kinetics. This model was subsequently employed to analyze DSC heat flow and extract sensible, melting and decomposition reaction heats. The extracted set of kinetic and thermodynamic parameters was shown to simultaneously reproduce TGA and DSC curves. In the current study, this methodology was applied to polymers that produce a significant amount of carbon rich residue (char) upon thermal decomposition. The analyzed materials were a poly(methyl methacrylate)-poly(vinyl chloride) alloy (Kydex), polymerized diglycidylether of bisphenol A, poly(ethylene terephthalate), poly(paraphenylene terephthalamide) (Kevlar), polymerized bisphenol A cyanate ester, poly(phenylene sulfide), polyetherimide and poly(ether ether ketone). The materials that produced less than 40 wt.% of char upon decomposition were found to decompose endothermically. The materials whose char yield exceeded 40 wt.% were found to undergo an exothermic decomposition.