Creep Compliance Measurement

Abstract

There are to date very few experiments reporting the measurement of creep compliance or of creep curves with AFM, since most measurements in this field are performed with instrumented nanoindenters and experimental protocols for the acquisition of creep curves are usually not implemented in commercial microscopes. Yet, AFM offers two significant advantages: a better speed performance and a lower thermal drift. For example, the stepping time of an AFM can be smaller than 1 ms, whereas the stepping time of nanoindenters is commonly limited to ca. 1000 ms (Braunsmann et al., Polymer 55:219–225, 2014).

This section presents two hands-on examples. In the first one (Moeller, J Pol Sci B Pol Phys 47:1573–1587, 2009), creep measurements are compared with force–distance curves measurements analysed with Oliver and Pharr method. Limitations of both methods, mainly due to the occurrence of plastic deformations, are surveyed.

In the second hands-on example (Braunsmann et al., Polymer 55:219–225, 2014), the unique feature of AFM, i.e. the possibility of scanning the sample with resolution in the nanometre scale while acquiring creep curves, is exploited.