Nanoindentation of polyurethane with phase-separated fibrillar structure

Abstract

abstract: Polyurethane elastomer is investigated by atomic force microscopy (AFM) in a regime of fast nanoindentation (simultaneous getting relief and mechanical properties of the surface). The hard phase of the polymer has a fibrillar structure and inhomogeneously distributed in the softer matrix. The surface is covered by a nanolayer of the soft phase and the obtained relief depends on the depth of indentation: it is necessary to pierce this outer layer to reach the internal fibrillar structure of the polymer. The rate of indentation is not constant and affected by the spring properties of AFM-probe, local phase composition and the depth of indentation. Analysis of the kinetics of the probe-surface interactions allowed to determine the thickness of the outer layer and to establish relationships between the indentation rate and elastic and dissipative properties of the soft and hard regions of the polyurethane surface.

Keywords

• Polyurethane
• Atomic force microscopy
• Nanoindentation