Enthalpic and Entropic elasticity can anybody throw some light on the subject...

Google Books permalink:http://books.google.com/books?id=_ZkeAQAAIAAJ
There's a table on Page 310 (Section 7.1) that explicitly addresses your question.

The elasticity of polymers is mostly due to entropic effect. The polymer chains want to stay random and form ball shape to increase the configurations. When the polymer chains are stretched, the chains deform in the stretched direction, form elliptical shape for example and decrease the configurations. This process is reversible, the elasticity is entropic, and the deformation is usually big. In contrast, for metals and ceramics, the elasticity is due to the stretching of bonds, which is enthalpic and usually the deformation is small.