In recent years, Teflon bellows have been widely used in nuclear power, non-ferrous metal smelting and petrochemical industry because of their unique corrosion resistance, good fatigue resistance and so on. In order to use the Teflon bellows better, this paper studies the stiffness properties of the Teflon bellows on the basis of the mechanical properties of the PTFE materials
and the relevant experimental results, and the corresponding empirical formulas are obtained.
Teflon referred to as PTFE, it is a kind of white waxy thermoplastic. Due to the molecular structure characteristics of PTFE, on the one hand, it has great deformation capacity; on the other hand, it can generate deformation after being stressed like other elastic materials (such as metal). At the same time, it is similar to viscous substances (such as polymer molten fluid). The deformation is not only related to load and temperature, but also affected by time factors, that is, "viscoelastic" characteristics.
The large deformation capacity of PTFE is much larger than that of common metal materials, and the fracture elongation of PTFE is measured as 233% according to GB1040-79. This ability to deform is due to its unique molecular structure. PTFE is a straight chain nonpolar polymer. No branched chain exists in the molecule. Due to the regularity of the chain and the symmetry of the molecules, large molecules are easy to be arranged in parallel, and a large molecule can be folded back and forth. In the polymer, the ordered crystal region can be formed, with high crystallinity, generally 57~75% and up to 93~97%. PTFE is commonly used as a "mixture" between solid crystal zone and amorphous zone.