Estimating work of adhesion using spherical contact between a glass lens and a PDMS block

This study proposes a method of estimating the thermodynamic work of adhesion using the spherical contact between a glass lens and a polydimethylsiloxane (PDMS) block. An equivalent stiffness of the measurement system is determined prior to the experimental measurements. Parameters such as force, contact radius, and displacement are measured during the contact processes that consist of a loading process and an unloading process. The elastic modulus of the PDMS is determined from the measured parameters. Hysteresis is observed in the contact process, showing that the process is in a non-equilibrium state. However, an equilibrium instant exists when the contact area attained a maximum value. The work of adhesion can be determined from the strain energy release rate using the parameters of the instant. The estimated work of adhesion is in the range estimated by another method. The limitation of the conventional method is also presented. The proposed method is suggested to be applicable to interface characterization in a practical adhesive contact with soft materials.