Mechanical properties of adhesives in situ and in bulk

The mechanical properties of adhesives are determined either from bulk material samples or from adhesively bonded joints (i.e., in the in situ form). Over the years there has been controversy as to whether the mechanical properties obtained through testing of the bulk material are representative of the adhesive in its thin-film form. In the design process it is important to know unambiguously the mechanical properties of the materials being used. This work deals with a thorough experimental investigation of the elastic properties of adhesives using Moire interferometry. It is shown that the mechanical properties of adhesives obtained from bulk specimens are no different from those obtained from tests on the adhesives in a thin-film form.