Raman spectrum and vibrational assignment for poly(tetrafluoroethylene)

Abstract

The Raman spectrum of polytetrafluoroethylene has been recorded under various conditions of sample crystallinity and temperature. Depolarization data for a perfluoropropylene–perfluoroethylene copolymer have also been recorded. From these a complete vibrational assignment has been made. The bands at Δ_ν= 576 and 597 cm^–1 whose intensity varies markedly with temperature have been discussed, the former being assigned to the E₁ CF₂ rocking fundamental and the latter to the rocking of a CF₂ group at a reversal in screw sense of the helical chains in the crystalline phase. The i.r.-active temperature-sensitive band at 625 cm^–1 is assigned to the out-of-phase motion of the two chain segments on either side of such a point.