PTFE (polytetrafluoroethylene) is totally unique. It is an inert material, therefore it has excellent resistance to most mineral and organic chemicals such as acids, bases and solvents. It can be used in temperatures up to approximately 260ºC.
PTFE is generally used in the presence of aggressive chemicals as it is inert. It can be supplied as a bore liner to shield pipe gaskets from chemical attack: these are supplied to fit specific bore sizes and are known as PTFE envelopes.