Isolated Chains as Hookean Elements

As has been shown elsewhere in this book (Chapter 1), a flexible high molecular weight chain can be represented by a large number N of freely jointed segments of length b. According to Eqs. (1.13) and (1.14), the free energy associated with a freely jointed chain whose end-to-end distance is r can be written as (4) 

the force necessary to keep the two ends of the chain at the distance r 

This equation indicates that an isolated molecular chain behaves like a Hookean elastic element. 

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