CONTACT ANGLES OF LIQUIDS ON FILMS FROM EMULSION ADHESIVES, AND CORRELATION WITH THE DURABILITY OF ADHESIVE BONDS TO POLYSTYRENE

Contact angles have been measured for a number of liquids against the surfaces of dried films from various emulsion adhesives. From the results have been calculated the dispersive and polar components of the surface free energies of the film surfaces, and also the thermodynamic work of adhesion to polystyrene in dry conditions and in the presence of water. The properties of the surfaces of adhesives dried against air, polystyrene and polytetrafluoroethylene are very similar. One of the adhesives was found to have a particularly polar surface. This causes the thermodynamic work of adhesion to become negative in the presence of water, implying that the particular adhesive bond to polystyrene is unstable in the presence of water. This prediction has been confirmed experimentally, in that expanded polystyrene beads bonded with this adhesive disintegrated when immersed in water.