Molten linear polymers mechanical and physical properties

3 Molten linear polymers mechanical and physical properties 

Molten polymers flow like (highly viscous) ordinary liquids when they are acted upon by very slow perturbations. However, at slightly higher frequencies co, they behave like a rubber. The threshold frequency coj = 1/t that separates the two spectral regions is strongly dependent on the chain length 

A famous equation by Einstein relates diffusion and mobility  

T being the temperature. Having established these concepts, we can at this point define x as the time necessary for the chain to move across the length L of the initial tube  

Since L JV and D,ube iV S we obtain x N. Experimentally one often finds an exponent slightly larger than 3 this disagreement has not yet been fully understood. 

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