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PTFE Surface Treatment And Bonding

There  are several reasons why PTFE is difficult to adhere: First, the surface  energy is low, and the critical surface tension is generally only 31 to  34 dyne/cm. Due  to the low surface energy and large contact angle, the adhesive cannot  fully wet PTFE, which can not adhere well to PTFE; Second, the  crystallinity is large, the chemical stability is good, and the swelling  and dissolution of PTFE are both To  be more difficult than non-crystalline polymers, when the adhesive is  coated on the surface of PTFE, it is difficult for the polymer chains to  spread and entangle with each other in the chain domain, and no strong  adhesion force can be formed. Third, the PTFE structure Highly symmetrical, it is also a nonpolar polymer. The  adhesion of the adhesive to the PTFE surface is caused by the van der  Waals force (intermolecular force). Van der Waals force includes  orientation force, inducing force, and dispersive force. The  surface of the non-polar high-molecular material does not have the  conditions for forming the orientation force and the inducing force, but  can only form a weaker dispersion force, and thus the adhesion  performance is poor.
 
Based  on the above understanding, in general, in order to solve the problem  of difficult adhesion of PTFE, people mainly proceed from the surface  modification and the synthesis of new adhesives.
 
▲ Surface treatment method
 
◆ Sodium-naphthalene complex chemical treatment
 
◆ High temperature melting method
 
◆ Radiation grafting
 
◆ Low temperature plasma technology
 
◆  Laser processing method (additive manufacturing method, material  modification, micro laser laser activation, electroless copper plating)