Elastomers, e.g. weakly crosslinked polymers, possess interesting properies. The elasticity of elastomers is based on entropic effects. In opposite to this, elasticity in classical materials like metals is based on energie. One consequence of this entropic origin is the unusual temperatur behavior of elastomers: With increasing temperature, the E-Modul of a elastomer under stress is raising proportional to the temperature.
This special property of elastomers can be used for the construction of a "Rubber Heat engine" shown in the schematic diagramm. With this machine, it is possible to use industrial waste heat and produce mechanical or electrical energie from it.
The functional principle can be shown with a simple prototype (heating with water of 60°C, cooling by air), see the above flash video. Alternatively, you can download a short film (*.wmv, 15 sec, 1.2 MB) showing it in operation.