The Stiffness of Rubber

This teaching and learning package is based on a two experiments which demonstrate the behaviour of rubber under tension. The first displays the unusual behaviour of a rubber strip when heated under tension; the second considers the behaviour of a rubber membrane under tension. In both cases the behaviour is considered theoretically in terms of the molecular structure of rubber and the thermodynamic entropy changes involved.

Photograph of contraction experiment

Aims Introduction Theory of rubber conformation Thermodynamics - the entropy spring Entropy derivation Contraction of rubber Contraction experiment Verification Biaxial tension Balloon experiment Summary Questions Going further

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First created: April 2004. Last updated: August 2006.