Nano-indentation is increasingly used to estimate the mechanical properties of polymeric films of nanometer-scale thickness. Hardness and modulus, as obtained on indentation are parameters that are strongly dependent upon tip geometry, elastic and inelastic material behavior, and specimen boundary conditions. The objective of this study was to analyze the mechanical response of nano-indentation loading on surfaces and interfaces of polymer films both linear and cross-linked. Polymer films on nano-indentation show confinement effect on their modulus and hardness. Reduced modulus and hardness in polyester and polycarbonate show strain softening that is associated polymer chain flexibility. The spatial constraints imposed to the plastic flow of the interface layer by the rigid indenter and substrate surfaces produce a dynamic effect, demonstrated by the loading rate dependence of the deformation response. In nano-indentation of cross-linked polymers, entanglements physical and chemical affect reduced modulus and hardness dependence on strain. Strain softening and strain hardening as well as dynamic frictional response are applied to indented polymer films consisting of surface, intermediate, and interface layers.

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