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Propriétés mécaniques de friction et de déformation des surfaces de polymères

Abstract : The motion of a hard tip on a polymeric surface generates an elastic slip or a plastic scratch, depending on the experimental conditions. During the scratching of a polymer, a viscoelastic relaxation takes place, and the scratch recovers partly at the rear face of the contact. The surface of the rear part of the contact depends on the level of the non recoverable plastic deformation in the elastic-plastic response. In the case of a fully elastic material, the rear contact face is quite identical to the front contact face. A scratch apparatus developed in our laboratory allows to measure the apparent friction when the tip moves at any temperature from –70 to + 120°C and with any speed between 0.001 and 10 mm/s. A built in microscope allows in situ control and analysis of the real contact area between the hard tip and the sample surface. The apparent friction is due to a true local friction part and to a geometrical “ploughing” part. The latter is due to viscoelastic and/or viscoplastic material flow ahead of the tip. The true local friction may be derived from the knowledge of the apparent friction and the contact geometry obtained by the in situ vision. A flow lines model was used to obtain quantitative values of the true friction coefficient. It was found that the true friction is a function of the level of plasticity in the material: the studied polymers exhibited a sharp increase of the true friction when the material beneath the tip undergoes plasticity: this effect was attributed to the adhesion hysteresis.
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Contributor : Sébastien Lafaye <>
Submitted on : Wednesday, May 7, 2003 - 1:44:16 PM
Last modification on : Thursday, May 7, 2020 - 1:37:50 AM
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Sébastien Lafaye. Propriétés mécaniques de friction et de déformation des surfaces de polymères. Autre. Université Louis Pasteur - Strasbourg I, 2002. Français. ⟨tel-00002808⟩

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