Modified-creep experiment of an elastomer film on a rigid substrate using nanoindentation with a flat-ended cylindrical tip

We have developed a modified-creep experiment with nanoindenter to measure the viscoelastic properties of elastomer films. Load-controlled experiments on PDMS (polydimethylsiloxane) films were performed using the Nano Indenter® XP with a flat-ended tip. By adapting the force–depth relation obtained by Choi et al. [S.T. Choi, S.R. Lee, Y.Y. Earmme, Acta Mater. (submitted for publication)], the indentation results were analyzed to obtain the relaxation modulus of the PDMS film as a function of time. Residual deformation on the indented PDMS film after unloading was measured with an atomic force microscope.