Analysis of microstructural deformation in polytetrafluoroethylene under heating or stretching conditions by synchrotron X-ray scattering

Abstract

The analysis of microstructure deformation in polytetrafluoroethylene (PTFE) under heating or stretching conditions is essential to determine the failure mechanism. This study employed the synchrotron X-ray scattering technique to study microstructural deformation in PTFE under heating (25~300 °C), different strains at room temperature, and constant stress at variable temperatures (25~175 °C). The results indicate that the scattering the scattering intensity of PTFE increases with an increase in the temperature, and the imperfect crystals gradually melt. When PTFE was stretched under relatively lower strains at room temperature, its molecular chains tilted and lamellar crystals slid and rotated along the stretching direction. Moreover, when PTFE was stretched at constant stress and varying temperatures, its imperfect crystals gradually melted with an increase in the temperature and lamellar crystals were fractured by stress; the crystals were further fractured owing to the α-transition temperature caused by the movement of molecular chains in the amorphous regions.

Keywords

• polytetrafluoroethylene
• microstructure
• synchrotron radiation
• small-angle x-ray scattering (saxs)
• ultra small-angle x-ray scattering (usaxs)