ABSTRACT
Generally, fluoropolymers are among the organic materials with the highest resistance to thermal degradation; however, there are significant differences between them. Relative thermal stability of selected fluoropolymers was studied by thermogravimetry [1]. The findings indicated that ethylene tetrafluoroethylene (ETFE) has the lowest thermal stability, which can be explained by the presence of ethylene linkages in its molecule. Fluorinated ethylene propylene (FEP) is next, and in spite of being fully fluorinated its lower-than-expected thermal stability is very likely due to a high degree of –CF3 branching. Perfluoroalkoxy (PFA) is more stable than FEP because of the presence of a stable, highly shielded ether group in its structure [2]. Polytetrafluoroethylene (PTFE) is the most stable of this group since its hydrocarbon backbone is protected by the large fluorine atoms attached by a very strong bond. There are two competing thermal degradation mechanisms, namely, unzipping (depolymerization) to form monomer and chain transfer reactions. The high-energy, very strong C-F bond makes depolymerization the dominant mechanism, whereas weaker C-H and C-Cl bonds promote thermal degradation by chain transfer reaction [2].
