Dynamic nanoindentation as a tool for the examination of polymeric materials

Abstract

The determination of the mechanical properties of polymers is more complex than that of many other structural materials, because they display time-dependence in their response to load. Generally, dynamic analysis techniques, such as dynamic mechanical thermal analysis (DMTA), are used to characterize the viscoelastic properties of bulk polymers. However, polymers are increasingly being used as thin films, the properties of which are not readily determined using conventional techniques. Nanoindentation offers the possibility of determining the properties of thin films but has generally only been used to measure static properties. Dynamic nanoindentation equipment has recently become available, but its accuracy with soft polymers is unproven. This paper presents results of a comparison between dynamic nanoindentation, DMTA, and differential scanning calorimetry (DSC) for the determination of the thermal response of four different polymers. A favorable comparison is shown, indicating that dynamic nanoindentation is capable of measuring the time-dependent properties of small samples of polymers.