Extrinsic Measurement of Carbon Black Aggregates Distribution within a Fluoroelastomer Matrix from Nanoindentation Experiments.

A novel extrinsic measurement of the particle surface distribution in a carbon black filled elastomer via nanoindentation is developed. This method is based on the measurement of the contact stiffness obtained from the Continuous Stiffness Measurement (CSM) mode. The proposed tip-particle model is held by two main hypotheses: the particles do not deform significantly during indentation so that only the elastomer matrix elastically deforms; particles are physically bounded with the surrounding matrix. Therefore, when the tip enters in contact with a particle, the latter becomes a hard extension of the tip, able to deform the elastomer matrix. Finally, the evolution of measured contact stiffness is directly related to the increase of contact area between the tip-particles set and the elastomer matrix. The proposed model is validated through a numerical and an experimental study. Moreover, an evaluation of the measurements bias allows to correct the particle surface distribution. A good agreement is found between the distribution measured from TEM observations and nanoindentation measurements.