Heat Stability and Degradation of Thermostable Prepolymers in a Controlled Atmosphere

Abstract

The liquid study of propargylic monomers during heat treatment has shown the formation of secondary phenolic products in the reaction mixture. They are in the form of propargyl-phenol and chromene-phenol and could be the weak links in the thermal properties of the final polymer. Moreover, we note some differences between the reactivities of the two monomers, probably related to the nature of the central pivot of the skeleton. Solid state analyses by FTIR and solid state crossed polarization magic angle spinning 13C NMR have confirmed the structure of the final polymer, and the reaction paths proposed and have enabled the heat cycle used to be validated. Thermal analyses have shown that the fluorine pivot confers the best thermal properties on the crosslinked material and influences the reactivity and degradation mechanisms of the compounds. In addition, the degradation of the crosslinked compounds occurred as a single step for the dipropargyl ether of bisphenol A and as two steps for the dipropargyl ether of hexafluorobisphenol A.