Evaluation of viscoelastic characteristics by indentation technique and application of time-temperature superposition principle

Indentation technique was applied to evaluate the viscoelastic characteristic of a polymeric material. In addition, time-temperature superposition principle was used to obtain the master curve of the viscoelastic characteristics. In the present stydy, load controlled indentation test with a Berkovich indenter was performed on Polypropylene (PP). The results showed that the measured penetration depth exhibits typical creep behavior of viscoelastic materials. The viscoelastic and plastic deformation can be separated from the measured penetration depth through the shape measurement of impression by using AFM. Creep compliance estimated by the viscoelastic deformation are in good agreement with that obtained by tensile creep test. Moreover, the master curves evaluated by indentation and tensile creep test were corresponding over a wide range of the reduced time. This fact means that indentation is useful technique for the measurement of viscoelastic characteristics of polymeric materials.