Thermoplastic polymer with a high crystalline proportion, known for example by the brand name Teflon. Chemically extremely stable, is attacked only by dissolved or melted alkaline metals. Thermally stable up to min. 400 °C, excellent gliding characteristics, very low surface energy (approx. 18 mN/m), accordingly a strong hydrophobic and oleophobic effect; used as non-stick coating. Can be used in optical data transmission for its low hardness, non-transparency and very low refraction index. PTFE is considered practically “non-gluable” but by means of plasma activation with hydrogen as a process gas it can be activated in such a way that even very good bonding can be achieved with an ideally designed process. C-F bonds are broken up and the hydrogen reacts with the broken-off fluorine atom to form hydrogen fluoride, which is extracted via the vacuum pump. The carbon bond which is now free provided an excellent bonding spot for adhesives and coating materials.