Adhesive Bonding of Polymeric Materials

The use of adhesive bonding for the creation of a permanent bond between structural elements of the same or different polymeric materials is especially advisable when large surfaces with complex shapes must be joined to operate in structures under conditions of shear and tension and when the shape and properties of the bonded materials must be preserved. The strength of the bonded joint depends on the adhesion of the bonded surfaces to the adhesive layer, the cohesive strength of the adhesive layer, and the strength of the polymeric materials themselves. The strongest bonds are obtained with adhesives whose polymer base is similar in chemical nature to the polymer base of the bonded materials. In particular, thermosetting adhesives are most suitable for thermosetting plastics and thermoplastic adhesives are best for thermoplastics. Certain all-purpose adhesives, for example, epoxies, polyurethanes, polyacrylics, and rubber adhesives, may be used for a variety of polymeric materials.

The technological process of adhesive bonding of polymeric materials involves the preparation of the surfaces to be bonded (roughing, shotblasting and sandblasting, etching, electric discharge action, and degreasing with organic solvents) and the application of the adhesive by methods similar to those used in applying paint and varnish coatings. The adhesive layer is then allowed to stand until the solvent is removed. Next, the surfaces to be joined are placed in contact and allowed to stand, sometimes with the application of heat and pressure. The quality of the adhesive seam can be determined by subjecting the bond to shearing stress or by using ultrasonic techniques.