9 ноября, 2015 
Pokraskin Good wetting of the substrate surface is essential for developing reliable bonds. Adhesives that do not wet the surface will not spread out and fill substrate surface irregularities. Wetting occurs when the surface tension of the liquid adhesive is lower than the critical surface tension of the substrates being bonded (see Section 6.1).
In many applications one of the benefits of using adhesives is that surface treatments are not normally required on engineering plastics and indeed in many applications parts are bonded ‘as received’. Nevertheless, a well-defined surface finish will optimise bonding and ensure the repetition of bonding characteristics on large assembly lines by maintaining the designed quality levels. Slightly roughened surfaces will be beneficial [6] and in certain applications this can be achieved by spark eroding the surface of the mould to provide a key for the adhesive.
Solvent cleaning with solvents such as isopropyl alcohol is generally a very acceptable cleaning method although it should be noted that sometimes these solvents can stress crack or craze some amorphous thermoplastics [7]. They can also remove all traces of moisture from the surface and this can slow down or even inhibit the cure of cyanoacrylates.
Correct surface preparation also results in improved durability [8] (see Section 9.1.1).
No single adhesive will satisfy all needs. Designers and engineers must balance a variety of adhesive properties to obtain the required bond strength and ease of use in production.
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