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 resu lts have been calculated the dispersive and polar components of the su rface free energies of the film surfaces, and also the thermodynamic w ork of adhesion to polystyrene in dry conditions and in the presence o f 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 i s unstable in the presence of water. This prediction has been confirme d experimentally, in that expanded polystyrene beads bonded with this adhesive disintegrated when immersed in water.