Structural study of a series of ethylene-tetrafluoroethylene copolymers with various ethylene contents, Part 1: Structure at room temperature investigated for uniaxially-oriented samples by an organized combination of 2D-WAXD/SAXS and IR/Raman spectra

The X-ray fiber diagrams, polarized infrared/Raman spectra, and small-angle X-ray scattering data have been successfully measured for a series of uniaxially-oriented ethylene (E)-tetrafluoroethylene (TFE) random copolymers. The difference in crystal structure and morphology has been investigated. All the samples of E/TFE copolymer were found to take the planar-zigzag conformation at room temperature except pure polytetrafluoroethylene case. The layer line intensities of the X-ray fiber diagram and the 00l reflection intensities were found to change systematically. From this, the E and TFE sequences were considered to be included commonly in a crystal lattice. The detailed investigation of the polarized infrared and Raman spectra allowed us to assign the bands to some characteristic structures. These can be used effectively in the study of structural changes occurring in the phase transition of these copolymer samples. The 2-dimensional small-angle X-ray scattering patterns were compared among the copolymers and the difference in stacked lamellar structure has been discussed.