Why is difficult to stick PTFE, the most important are the following reasons: first, low surface energy, the critical surface tension of normal, only 31 to 34 dyne / cm. Due to low surface energy, contact angle, can not be sufficiently adhesive wetting PTFE, and thus not well adhered to the PTFE; secondly, the degree of crystallinity, good chemical stability, PTFE swell and dissolve better than non-crystalline polymer difficulties begin when the adhesive coated on the PTFE surface hardly occurs polymer molecular chain into chain domain proliferation and entangled with each other, can not form a strong adhesion; third, PTFE structure highly symmetric, also belong to the kind of non-polar molecules high. PTFE and adsorbed on the surface of the adhesive by van der Waals forces (intermolecular forces) and caused by van der Waals forces comprising the alignment, induction forces and dispersion forces. For the surface of the non-polar polymer materials, do not have the ability to form an alignment force and induction conditions, and can only form a weak dispersion forces, and thus poor adhesion properties.
Based on the above understanding, in general, in order to solve the problem of bonded PTFE difficult, people mainly synthetic surface modification and departure from the new adhesive.