Characterization of elastic modulus and work of adhesion in elastomeric polymers using microinstrumented indentation technique

This study combines Johnson-Kendall-Roberts (JKR) theory with the instrumented indentation technique (IIT) to evaluate the work of adhesion and modulus of elastomeric polymers. Indentation testing was used to obtain load-displacement data for contact between a tungsten carbide indenter and the elastomeric polymer. The JKR contact model, which was designed to take polymer viscoelastic effects into account, was applied to adjust the contact area and the elastic modulus, which the Hertzian contact model would respectively underestimate and overestimate. In addition, we obtained the thermodynamic work of adhesion by considering the surface energy in this contact model. In order to define the relation between the JKR contact radius and applied load without measuring the contact radius optically, we used a relation between applied load and contact stiffness by examining the correlation between the JKR contact radius and stiffness through dimensional analysis with 14 elastomeric polymers. This work demonstrated that the interfacial work of adhesion and elastic modulus of a compliant polymer can be obtained from simple instrumented indentation testing without area measurement, and provided an algorithm for compliant polymer characterization.