Entropy and Elasticity in Keratin and Myosin

Abstract

A GOOD deal of attention has been directed lately¹ to the question of rubber-like elasticity in high polymers, and experiments based on thermodynamic arguments have emphasized, in the case of rubber itself, the importance of the contribution of decreasing entropy to the load at high extensions. That high elasticity is not always due to entropy is, however, shown by my results for keratin (Cotswold wool), which confirm what on other grounds has always appeared certain, that the normal elastic mechanism in keratin involves chiefly the internal energy: extensions up to some 20 percent are accompanied by an increase in entropy ; and although at higher extensions the entropy decreases, it is only at a rate which contributes relatively little to the load. Similar results have been reported by Bull² for human hair.