Relation between Viscoelastic Properties of Polyvinyl Acetate and Adhesive Strength

Physical properties of polyvinyl acetate (PVAc) polymerized in solution vary in very wide ränge äs temperature increases from -100°C to -f 100°C The state of the material changes from glassy to rubbery and then to fluid, and accordingly tensile storage modulus (E') changes from 2 10 dyne/cm to less than l O dyne/cm. Adhesive shear Strength, adhesive tensile Strength and peel Strength for Kaba (Betula Maximowicziana RGL) and/or aluminium were measured in the temperature ränge — 100°C to 100°C in order to get informations on the relation between mechanical properties of adhesives and adhesive Strength. It was found that adhesive shear Strength becomes maximum at 30-35°C, where E' of the polymer is about 1.5 10 dyne/cm at 110 Hz which corresponds to the shear storage modulus (G') bf 5 9 dyne/cm, that adhesive tensile Strength becomes maximum at 40—45 °C, where E' is about 5 9 dyne/ cm, and that peel Strength becomes maximum at 70°C where E' is about 10 dyne/cm. These characteristics are substantially in good agreement with those found in some other adhesives, and the ideas on mechanism of wood adhesion previously proposed by us are supported data of this study.