Nanoindentation of Polymers: An Overview.
Nanoindentation of Polymers: An Overview.
(774 K)
VanLandingham, M. R.; Villarrubia, J. S.; Guthrie, W.
F.; Meyers, G. F.
Advances in Scanning Probe Microscopy of Polymers.
Macromolecular Symposia. Volume 167. Proceedings.
2001, Tsukruk, V. V.; Spencer, N. D., Editor(s)(s),
15-44 pp, 2001.
Keywords:
polymers; atomic force microscopy (AFM); Berkovich
indenter; blind reconstruction; depth-sensing
indentation (DSI); interfacial force microscope (IFM);
load frame compliance; statistical uncertainties; tip
shape calibration; Young's modulus
Abstract:
In this paper, the application of instrumented
indentation devices to the measurement of the elastic
modulus of polymeric materials is reviewed. This review
includes a summary of traditional analyses of
load-penetration data and a discussion of associated
uncertainties. Also, the use of scanning probe
microscopes to measure the nanoscale mechanical response
of polymers is discussed, particularly with regard to
the associated limitations. The application of these
methods to polymers often leads to measurements of
elastic modulus that are somewhat high relative to bulk
measurements with potentially artificial trends in
modulus as a function of penetration depth. Also, power
law fits to indentation unloading curves are often a
poor representation of the actual data, and the power
law exponents tend to fall outside the theoretical
range. These problems are likely caused by
viscoelasticity, the effects of which have only been
studied recently. Advancement of nanoindentation testing
toward quantitative characterization of polymer
properties will require material-independent calibration
procedures, polymer reference materials, advances in
instrumentation, and new testing and analysis procedures
that account for viscoelastic and viscoplastic polymer
behavior.
