Screening of excluded volume

Fig. 21(a) that, in contrast to the case of polymer melts where the screening of excluded volume interactions leads to 1/2, in the porous medium... 

In the case of full screening of excluded volume he obtained... 

Fig. 9. Relation between relaxation exponent n and fractal dimension d for a three-dimensional network. In case of complete screening of excluded volume, values of 0 < n < 1 are possible if d is chosen between 1.25 and 2.5...

The swollen fractal dimension is due to solvent around the big cluster.The solvent may consist of unreacted molecules and of smaller clusters, so that the excluded volume forces are screened on small scales but not on scales involving larger parts of the infinite cluster than a typical solvent cluster. Screening of excluded volume forces on the scale of distances between two crosslinks is due to the presence of unreacted chains. Thus one can assume that the chains between crosslinks are still Gaussian and = Df -h 2 is still valid. 

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