Adhesive Bonding

10 Pages 2483 Words

the Americans also adopted this process to produce the most effective aircraft of the war, the De Havilland Hornet which used the adhesive to bond the aluminum extrusions to the capped wing spars (4, 41).

Adhesives have since grown considerably and since no one universal adhesive exists up to date, the boundaries are limitless. They can be found in mostly all types of industries, from high tech aerospace to dishwashing machines, and are more and more, replacing conventional ways of fastening joints, namely mechanical fasteners and welding process.

Principles of Bonding:
In most cases, monomers are applied to it’s adherent ( part to be jointed) and are turned into polymers, which are long chain type molecules, by means of diverse catalyst ranging from heat, pressure or some other chemical compound all depending on the type of adhesive used.

The reason why the bond takes place between the mating surfaces however has taken different theories over the past years. The three most common, principle of diffusion, principle of mechanical adherence and the principal of inter-atomic bonding have been well more developed than other explanations of why adhesive bonds occur.

The diffusion principle states that at polymerization, some of the molecules diffuse in the adherent and consequently, some molecules of the adherent diffuse into the adhesive in order to form a solid joint. The mechanical principal states that, the imperfections on the wetted surface of the adherent serve as to grip the adhesive when it turns into it's solid polymer state and takes advantage of these imperfections to establish a solid bond. However, this might not help in explaining why perfectly strong bonds are also possible on highly polished surfaces. The third and most generally accepted theory attributes the bonding forces to the fact of the sharing of valence electrons between the newly formed polymer and the adhered material. Some may like ...