Characteristics of the structure and properties of low-temperature fractions recovered from the powder ultradispersed polytetrafluoroethylene by sublimation

Low-molecular fractions were recovered through sublimation of the ultradispersed powder polytetrafluoroethylene (UPTFE) under isothermal conditions and specified temperatures. The present paper describes the results of study of the fractions recovered at 50–100 °C with an increment of 10°. The studies revealed that the obtained fractions were in general characterized by a film structure, a paraffin-like phase composition with different crystalline structures, and a layered packing. Films of the fraction isolated at 50 °C have pores; those isolated at 60 °C had fibers. The molecular structures are represented by a short chain of molecules consisting of CF2 fragments with end CFCF2 groups. The chain length increases from 5 to 15 fragments along with the increasing temperature of the fraction isolation. The beginning and the process of decomposition of fractions depend on the temperature, at which the fraction of interest was obtained.