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Propriétés mécaniques et rhéologiques des mousses de polymères réticulés

Abstract : The use of cellular materials based on polymers like foam shows an increase interest, particularly for acoustic absorption. The objective of this work is to present new approaches for the characterization of these materials.
Many methods were developed in order to characterize these materials in their linear field, privileged area for acoustic absorption and determination of the current mechanical parameters. A first study presents the linear behavior on a very wide frequency scale by the application of Time-temperature Superposition (TTS) principle. The use of the TTS on a family of foams, obtained with same polymer, at same density, but with different pore size, shows two important aspects: a weak fraction of the solid skeleton takes part in shear stress transmission, and elastic modulus at zero shear frequency decreases with pore size.
Polymer foams are often used in their linear field, but their mechanical behavior differs on higher strain level.Tes stress-strain curves present an hysteretic behavior, with three different zones (linear, buckling, and densification). There are other hysteretic phenomena which were more simply modelled, such as the theory of Preisach-Krasnoselskii-Mayergoyz (PKM) resulting from magnetism. One second part of this work presents a new extension of this PKM theory to open cells cross-linkded polymer foams, subjected over great deformations: we can model hysteretic behavior observed in experiments, starting from microscopic hysterons distribution contains in a Preisach-Mayergoyz space.
In a third part, we studied the influence of stress past history on mechanical parameters measurements of cross-linked polymer foams. We concentrated particularly on the rheology of these foams within the framework of compression relaxation, by distinguishing two mechanisms, one in linear zone of loading and the other outwards. Dependent on the past history of stressing, this second mechanism of relaxation allows the stress reduction by topological rearrangement of the foam beams.
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https://tel.archives-ouvertes.fr/tel-00133963
Contributor : Mickael Deverge <>
Submitted on : Wednesday, February 28, 2007 - 11:18:24 AM
Last modification on : Tuesday, March 31, 2020 - 3:20:47 PM
Long-term archiving on: : Wednesday, April 7, 2010 - 2:53:07 AM

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  • HAL Id : tel-00133963, version 1

Citation

Mickael Deverge. Propriétés mécaniques et rhéologiques des mousses de polymères réticulés. Acoustique [physics.class-ph]. Université du Maine, 2006. Français. ⟨tel-00133963⟩

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