Solvent bonding

 ( Bonding ) 

Solvent bonding (also called solvent welding) is not a method of adhesive bonding (the final result does not rely on the adhesion of another substance adhesive and its cohesion between two substrates), but rather a method of fusing two thermoplastic plastic joining. Application of a solvent to a thermoplastic material softens the polymer, and with applied pressure this results in polymer chain interdiffusion at the bonding junction. When the solvent evaporates, this leaves a fully consolidated bond-line. An advantage to solvent bonding versus other polymer joining methods is that bonding generally occurs below the glass transition of the polymer.

Solvent bonding differs from adhesive bonding, because the solvent does not become a permanent addition to the joined substrate. Solvent bonding differs from other plastic welding processes in that heating energy is generated by the chemical reaction between the solvent and thermoplastic, and cooling occurs during evaporation of the solvent.

Solvent bonding can be performed using a liquid or gaseous solvent. Liquid solvents are simpler and generally have lower manufacturing costs but are sensitive to surface imperfections that may cause inconsistent or unpredictable bonding. Some solvents available may not react with the thermoplastic at room temperature but will react at an elevated temperature resulting in a bond. Curing times are highly variable.