conditions depend on the used materials. Hardening of the adhesives are possible: at room temperature through heating cycles using UV light by applying pressure Surface preparation of plastics To create a desirable surface for the adhesive bonding of plastics, there are three major requirements: the weak boundary layer of the given material must be removed or chemically modified to create a strong boundary layer; the surface energy of the adherend should be higher than that of the adhesive for good wetting; and the surface profile can be improved to provide mechanical interlocking. Meeting one of these major requirements will improve bonding; however, the most desirable surface will incorporate all three requirements. Numerous techniques are available to help produce a desirable surface for adhesive bonding. Degreasing When preparing a surface for adhesive bonding, all oil and grease contamination must be removed in order to form a strong bond. Although the surface may appear to be clean, it is important to still use the degreasing process. Prior to performing the degreasing process, the compatibility of the solvent used and the adherend must be considered to prevent irreversible damage of the surface or part. Vapor degreasing One method of degreasing is that of vapor degreasing, in which the adherend is dipped in a solvent. When removed from the solvent, the vapors condense on the surface of the adherend and dissolve any contaminants that had existed. These contaminants then drip off the adherend with the condensed vapors. In lieu of vapor degreasing The other method of degreasing requires a cloth or rag soaked in solvent, which can be used to wipe down the surface of the adherend to remove contaminants. It is important that all residue that had been left behind from the solvents be removed, so that there is no detrimental effects to the adhesive bonding. Following degreasing process After degreasing, a good test to determine cleanliness of the surface is to use a drop of water. If the drop spreads on the surface, a low contact angle and good wettability has been achieved, which indicates the surface is clean and ready for application of the adhesive. If the drop beads up or retains its shape, the degreasing process should be repeated. Abrasion In general, abrasion is superior to other methods of surface preparations due to the fact that it is simple to perform, and it does not produce a significant amount of