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 plastics. 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 temperature 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.
