| Abstract: | In an effort to elucidate the structure of the low-temperature phase of PTFE, a spectroscopic study of the effect of progressive irradiation on the low-frequency infrared spectrum was undertaken. Previous infrared and Raman measurements indicated that irradiation of PTFE decreases its crystalline content, resulting in a lowering of the 19°C phase transition temperature due to the introduction of disorder and defect structures into the lattice by chain scission. Far-infrared studies of virgin and irradiated PTFE at liquid nitrogen temperatures show that the medium to strong bands at 45, 54, 58, and 71 cm?1, attributed to lattice vibrations, decrease in intensity as the crystalline content decreases. These findings support the assignment of these bands to intermolecular vibrations of the crystalline lattice and are an indication of the presence of more than one molecule in the crystallographic unit cell. |
