Caractérisation in-situ des mécanismes de dispersion de la silice dans une matrice élastomère soumise à un cisaillement

Abstract : We identified, using a rheo-optical counter-rotating device, the dispersion mechanisms of precipitated silica agglomerates (Z1115MP and Z1165MP) immersed in a visco-elastic matrix (SBR 25E) submitted to shear and determined the key parameters affecting the dispersion process. The effects of the silica type, the agglomerate grafting with a silane covering agent, their infiltration by polymer chains and the filler concentration on the mechanisms and criteria of dispersion were studied. The main results are:
- Z1165MP agglomerates disperse via a rupture mechanism and Z1115MP agglomerates via a disintegration mechanism. Both mechanisms occur at a critical hydrodynamic stress. Z1165MP is more difficult to disperse than Z1115MP. The differences in mechanisms and criteria of dispersion are discussed in terms of structural organization of silica.
- The grafting of Z1115MP agglomerates with a covering agent does not modify the dispersion mechanism but decreases considerably the agglomerate cohesion thus reducing the critical stress for disintegration.
- When Z1115MP agglomerates are fully infiltrated by the elastomer matrix, a new dispersion mechanism is observed: dislocation. It occurs at a critical hydrodynamic stress which is directly proportional to the agglomerate radius.
- In a concentrated medium, both silica types disperse via successive removals of fragments induced by collision.
In similar hydrodynamic conditions, the dispersion kinetics of a Z1165MP agglomerate are five times slower than for a same size Z1115MP agglomerate.
All those results bring essential information on the effects of different parameters on dispersion mechanisms of silica during the industrial mixing process.
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Submitted on : Tuesday, December 30, 2008 - 3:19:14 PM
Last modification on : Monday, November 12, 2018 - 10:58:56 AM
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  • HAL Id : tel-00349422, version 1

Citation

Céline Roux. Caractérisation in-situ des mécanismes de dispersion de la silice dans une matrice élastomère soumise à un cisaillement. Mécanique [physics.med-ph]. École Nationale Supérieure des Mines de Paris, 2008. Français. ⟨NNT : 2008ENMP1561⟩. ⟨tel-00349422⟩

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