0000000001252834
AUTHOR
D Tranchida
Linking structure and mechanical properties via instrumented nanoindentations on well-defined morphology poly(ethylene) Polymer 50 8 1939-1947 2009
Several poly(ethylene) samples with a broad range of morphologies were studied in this work using nanoindentations. The samples had degrees of crystallinity ranging from 30 to100% while their Young’s modulus ranged from few tens of MPa up to several GPa. Experimental conditions for the correct evaluation of Young’s modulus were at first identified, choosing a suitable loading rate in order to minimize viscoelastic effects on the unloading. The force curves, i.e. plots of applied load vs. penetration depth, were then analyzed following two common procedures available in the literature. None of these procedures leads to satisfying results when compared to other experimental techniques. Howeve…
Nanoscale mechanical characterization of polymers by atomic force microscopy (AFM) nanoindentations: Viscoelastic characterization on a model material
The Atomic Force Microscope (AFM), apart form its conventional use as a microscope, is also used for the characterization of the local mechanical properties of polymers. In fact, the elastic characterization of purely elastic materials using this instrument can be considered as a well assessed technique while the challenge remains the characterization of the viscoelastic mechanical properties. In particular, one finds the mechanical behavior changing when performing indentations at different loading rates, i.e., on different time scales. Moreover, this apparent viscoelastic behavior can also be due to complex contact mechanics phenomena, with the onset of plasticity and long-term viscoelast…