Influence of the Bonding Solvent on the Structure and Strength of Solvent Welded Joints

Abstract The influence of the bonding solvent on the strength of solvent welded joints has been studied. Strong solvent welds are produced with solvents having the greatest ability to dissolve the polymer and not with solvents which could diffuse most rapidly into the adherend. The formation of a gel layer of highly mobile chains (on the application of a good solvent to the mating surfaces) promotes extensive and intimate bonding across the original interface so that no plane of weakness is obtained. Such welds exhibit high strength since they do not have any preferred plane of failure and extensive deformation of the weld accompanies crack initiation and propagation. When a poorer bonding solvent is used, solvent welds with lower strengths are obtained since soft and weak interfacial layers form at the original interfaces of the weld.