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On the Use of the Nanoindentation Unloading Curve to Measure the Young's Modulus of Polymers on a Nanometer Scale
Author(s) -
Tranchida Davide,
Piccarolo Stefano
Publication year - 2005
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.200500538
Subject(s) - nanoindentation , indentation , materials science , amorphous solid , nanometre , contact mechanics , modulus , composite material , elastic modulus , atomic force microscopy , contact area , penetration depth , polymer , optics , nanotechnology , crystallography , physics , chemistry , thermodynamics , finite element method
Summary: The nanoindentation test is a fundamental tool to assess the link between morphology and mechanical properties. The preliminary results of a more exhaustive study about the applicability to polymers of the most used procedure to determine elastic modulus by indentation are reported in this short communication. A departure of the experimental conditions from the theoretical assumptions and results that give rise to the Oliver and Pharr analysis is shown to occur under a wide range of experimental conditions, with applied loads and penetration depths covering several orders of magnitude and using different indenter geometries. Unloading curves with exponents significantly larger than 2 are observed in disagreement with the contact mechanics approach used by Oliver and Pharr.An AFM image obtained in non contact mode of an indentation induced by a sharp AFM tip with a maximum applied load of ca 1.2 µN on amorphous PET.