FURTHER CALORIMETRIC EVALUATION OF POLYMER/OLIGOMER DECOMPOSITION: APTAC TESTING

Abstract

The behavior of polymers and oligomers subjected to elevated temperatures in an air-free environment was recently studied to characterize the energetics of polymer/oligomer decomposition. This work, which focused exclusively on hydrocarbon and oxygenated species tested in an open-pan DSC/TBA, was pursued to test a widely-held notion that polymer decomposition is endothermic in nature. Selected species have now been tested in the APTAC, a calorimeter designed to provide an adiabatic environment for runaway reaction characterization. Comparison of results with those from the DSC/TGA reveals confirmation of energetics in some cases and startling differences in others. For example, in both the DSC/TGA and the APTAC, polymers with double bond or glycidyl groups display exothermic reactions. However, polymers with ether or ester functionalities can exhibit exothermic decomposition behavior in the APTAC—in contrast to the DSC/TGA results. These findings reinforce the hypothesis that loss of heat by vaporization and removal of reactive intermediates by carrier gas in the DSC/TGA can confound the observed energetics of polymer/oligomer reaction. Furthermore, functional groups present in polymers/oligomers can strongly influence the reaction energetics.