Abstract
This study focused on the relationship between adhesion force and withdrawal speed, which is one of the primary time-dependent characteristics of the surface force. Highly precise measurement of the surface force was conducted using a surface force apparatus. Polydimethylsiloxane (PDMS) and glass (BK7) were used for the spherical probe and Si wafer was used for the plate sample. The results showed that the adhesion force, adhesion displacement, and withdrawal energy increased as the withdrawal speed was increased when the PDMS probe and Si sample were used in combination. These characteristics could not be seen in the adhesion forces between BK7 and Si. Moreover, we proposed an empirical theoretical model of the PDMS-Si contact assuming viscoelasticity. The spring constant and the damping coefficient of the contact were formulated as functions of the withdrawal speed and the displacement with reference to the experimental results. It was found that the spring constant decreases and the damping coefficient increases as the displacement increases or the withdrawal speed decreases.
