Analysis of pyrolysis products formed from ethylene–tetrafluoroethylene heterosequences of poly(ethylene- co-tetrafluoroethylene)

Abstract

Poly(ethylene- co-tetrafluoroethylene) (PETFE) was pyrolyzed and the pyrolysis products formed from the ethylene–tetrafluoroethylene heterosequences were analyzed using gas chromatography/mass spectrometry (GC/MS). Major pyrolysis products were 3,3-difluoropropene (DFP), 3,3,4,4-tetrafluoro-1-butene (TFB), 1,1,2,2,3,3-hexafluorocyclopentane (HFCP), 1,1,2,2,3,3-hexafluorocyclohexane (HFCH), 1,1,2,2,3,3,4,4-octafluorocyclohexane (OFCH), and 3-trifluoromethyl-3,4,4,5,5-pentafluorocyclohexene (FMPFCH). Their formation mechanisms were proposed. Peak intensity ratios of HFCP, HFCH, and FMPFCH compared to OFCH increased as the pyrolysis temperature increased, while those of DFP, TFB, HFCP, and HFCH compared to tetrafluoroethylene decreased. Order of the relative abundances of the major pyrolysis products formed from PETFE was OFCH > HFCP > HFCH > TFB > DFP. The order may be due to the difference in bond energies of CH 2–CH 2, CF 2–CH 2, and CF 2–CF 2. Formation of the pyrolysis product through the CH 2–CH 2 bond cleavage was more favorable than those through the CF 2–CH 2 and CF 2–CF 2 ones.