Submolecules friction coefficient

Each submolecule will experience a frictional drag with the solvent represented by the frictional coefficient /0. This drag is related to the frictional coefficient of the monomer unit (0- If there are x monomer units per link then the frictional coefficient of a link is x(0- If we aPply a step strain to the polymer chain it will deform and its entropy will fall. In order to attain its equilibrium conformation and maximum entropy the chain will rearrange itself by diffusion. The instantaneous elastic response can be thought of as being due to an entropic spring . The drag on each submolecule can be treated in terms of the motion of the N+ 1 ends of the submolecules. We can think of these as beads linked... 

Note that (R ) = r N. This equation is similar to the one obtained by Debye in his hydrodynamic calculation of the viscosity of a solution of free-draining chains. However, N here is the number of submolecules rather than the number of atomic groups, and the frictional coefficient of an atomic group is replaced by as Rouse pointed out. For experimental smdy, see Rouse s other two papers (1953, 1954). 

The friction coefficient fo now represents the frictional force per monomer unit per unit velocity encountered by a submolecule junction as it moves through a medium consisting of other polymer molecules it is ordinarily considerably higher than the fo of dilute solution theory, which is approximately proportional to solvent viscosity. 

The Rouse, Zimm and Bueche theories are satisfaetory for the longer relaxation times, which involve movement of submolecules. This has been eonfirmed for dilute polymer solutions, where the theory would be expeeted to be most appropriate [29,30]. More remarkably, it also holds for solid amorphous polymers (Referenee 11, Chapter 13), provided that the friction coefficient is suitably modified. 

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