Free-draining coil

An alternative point of view assumes that each repeat unit of the polymer chain offers hydrodynamic resistance to the flow such that f-the friction factor per repeat unit-is applicable to each of the n units. This situation is called the free-draining coil. The free-draining coil is the model upon which the Debye viscosity equation is based in Chap. 2. Accordingly, we use Eq. (2.53) to give the contribution of a single polymer chain to the rate of energy dissipation ... 

The function f(X) approaches a constant value for nondraining coils to generate Eq. (9.40), and approaches some constant times nf/r o(r o ) for free-draining coils to generate Eq. (9.44). 

It is clearly seen from Fig. 4.4 that JeR tends at low concentrations in the direction of the value for the non-draining case [ 0.2, eq. (3.62)], whereas at higher concentrations the value for free-draining coils [= 0.4, eq. (3.61)] is approached for some polymers, in accordance with the theoretical considerations given. The extrapolation to zero concentration,... 

The mutual influence of the particles leads to their shielding within the coil and the overall coefficient of the resistance of the coil proves to be smaller than that for a free-draining coil. The requirement of covariance in relation to successive subdivisions of the macromolecule into subchains gives rise, according to formula (2.14), to the following power dependence for large values... 

The BBB coil is so highly expanded that it behaves as a partially draining or free draining coil, in which case d In 0/d In M is very large. For a free draining coil we should put... 

A free-draining polymer molecule, referred to as the free-draining coil, is considered by dividing it into identical segments each of which has the same frictional coeflflcient Since solvent molecules permeate all regions of the polymer coil with equal ease (or difficulty), each segment makes the same contribution to / which therefore is given by... 

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