PCTFE is a thermoplastic fluoropolymer with excellent mechanical and chemical resistance properties. Exceptional is the wide termperature range it can handle starting from -250°C up to +180°C and melts around 216°C. This polymer is commonly used for cryogenic applications like gaskets and seals for gas distribution components.
Some active brand names for basic PCTFE material are Neoflon® (Daikin Chemicals) and voltalef® (Arkema). In the past a common used material was KEL-F® from 3M Corporation.
[source wikipedia]