5. FUJIWARA, S. KATSUMATA, AND T. SEKI
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the gel is formed when 7 = 1, and Re is defined as the critical dose, which is the minimum dose necessary for gel formation. k PPo 1/Rg
Pn
PI/^
=
PO X R J R
Experimentally, it was established that, R, X PO = 5.1 X lo8 1.37 X 108C, where C is the weight concentration of PVA in 100 g of water. If P, is obtained, the average distance from both ends of the molecule, i, is obtained by the following. Suppose that the PVA molecule undergoes Brownian motion, where vibration, rotation, and bending motions can take place. Then, =
