Abstract
Accurate mechanical characterization of viscoelastoplastic materials in small volumes is required for the development of polymeric thin film, nanocomposite, and biomedical applications. Instrumented indentation-based approaches are increasingly implemented to quantify the resistance to permanent deformation of such systems via time-independent analyses. Here, we quantify the significant post-indentation recovery of several bulk polymers via time-lapsed scanning-probe microscopy under ambient conditions, indicating up to 80% recovery of both indentation depth and volume within 48 h. This viscoelastic response demonstrates that indentation hardness values for these polymers are accurate within 10% for less than 5 min to 3.5 days post-indentation, neglecting any other analytical or experimental errors. Further, although the extent and rates of volumetric recovery depend strongly on loading history and polymer structure/physical properties, deformation resistance inferred from indentation hardness does not quantitatively or qualitatively predict recoverable work or residual deformation of polymer surfaces.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
M.R. VanLandingham, J.S. Villarrubia, W.F. Guthrie, G.F. Meyers: Nanoindentation of polymers: An overview. Macromol. Symp. 167, 15 (2001).
B.J. Briscoe, K.S. Sebastian: The elastoplastic response of poly(methyl methacrylate) to indentation. Proc. R. Soc. London Ser. A 452, 439–457 (1996).
B.J. Briscoe, P.D. Evans, S.K. Biswas, S.K. Sinha: The hardnesses of poly(methylmethacrylate). Tribology International 29, 93 (1996).
C. Klapperich, K. Komvopoulos, L. Pruitt: Nanomechanical properties of polymers determined from nanoindentation experiments. J. Tribol-T Asme. 123, 624 (2001).
W.C. Oliver, G.M. Pharr: An improved technique for determining hardness and elastic-modulus using load and displacement sensing indentation experiments. J. Mater. Res. 7, 1564 (1992).
B.T.A Chang, J.C.M Li: Indentation recovery of amorphous materials. Scripta Metall Mater. 13, 51 (1979).
I.M. Low: Effects of load and time on the hardness of a viscoelastic polymer. Mater. Res. Bull. 33, 1753 (1998).
V. Lorenzo, J.M. Perena, J.G. Fatou, J.A. Mendezmorales, J.A. Aznarez: Delayed elastic recovery of hardness indentations in polyethylene. J. Mater. Sci. 23, 3168 (1988).
V. Lorenzo, J.M. Perena, J.M.G Fatou, J.A. Mendezmorales, J.A. Aznarez: Interference microscopy measurements of depth at Vickers hardness indentations in polyethylene. J. Mater. Sci. Lett. 6, 756 (1987).
B.T.A Chang, J.C.M Li: Indentation recovery of atactic polystyrene. J. Mater. Sci. 15, 1364 (1980).
T.M. Kung, J.C.M Li: Recovery processes in amorphous polymers. J. Mater. Sci. 22, 3620 (1987).
F.Q. Yang, S.L. Zhang, J.C.M Li: Impression recovery of amorphous polymers. J. Electron. Mater. 26, 859 (1997).
C.A. Tweedie, J.F. Smith, K.J. Van Vliet: Nanomechanics of Polymer Energy Absorption, (Materials Research Society, Boston, MA, 2004).
R.J. Young, P.A. Lovell: Introduction to Polymers (Chapman & Hall, New York, 1991).
A. Brulet, F. Boue, J.P. Cotton: About the experimental determination of the persistence length of wormlike chains of polystyrene. J. Phys. II 6, 885 (1996).
J. Bicerano: Chain stiffness of liquid crystalline polyesters. 1. Characteristic ratio and persistence length. Comput. Theor. Polym. Sci. 8, 9 (1998).
S. Nikolov, I. Doghri: A micro/macro constitutive model for the small-deformation behavior of polyethylene. Polymer 41, 1883 (2000).
Y.G. Liu, S.Q. Bo, Y.J. Zhu, W.H. Zhang: Studies on the intermolecular structural heterogeneity of a propylene-ethylene random copolymer using preparative temperature rising elution fractionation. J. Appl. Polym. Sci. 97, 232 (2005).
F. Dinelli, G.J. Leggett, P.H. Shipway: Nanowear of polystyrene surfaces: Molecular entanglement and bundle formation. Nanotechnology 16, 675 (2005).
C.L. Soles, J.F. Douglas, W.L. Wu, R.M. Dimeo: Incoherent neutron scattering as a probe of the dynamics in molecularly thin polymer films. Macromolecules 36, 373 (2003).
L.E. Nielson: Mechanical Properties of Polymers and Composites, (Marcel Dekker, New York, 1974).
Y.T. Cheng, C.M. Cheng: Scaling, dimensional analysis, and indentation measurements. Mater. Sci. Eng., R 44, 91 (2004).
M. Dao, N. Chollacoop, K.J. Van Vliet, T.A. Venkatesh, S. Suresh: Computational modeling of the forward and reverse problems in instrumented sharp indentation. Acta Mater. 49, 3899 (2001).
L.G. Wang, M. Ganor, S.I. Rokhlin, A. Grill: Nanoindentation analysis of mechanical properties of low to ultralow-dielectric constant SiCOH films. J. Mater. Res. 20, 2080 (2005).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Tweedie, C.A., Van Vliet, K.J. On the indentation recovery and fleeting hardness of polymers. Journal of Materials Research 21, 3029–3036 (2006). https://doi.org/10.1557/jmr.2006.0377
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1557/jmr.2006.0377