Elastic property and Raman spectrum evolutions during dehydration process of polyacrylamide gel

Evolutions of the complex elastic stiffness and the Raman scattering spectrum were measured during the dehydration process of the polyacrylamide gel. The elastic-stiffness amplitude grew around 10³ times as large as the initial value and the loss tangent reached a peak around the time when the log of the simultaneously measured weight showed a bend point (t′g). Besides, in the Raman scattering experiment, a pair of broad peaks emerged in the low-frequency region around t′g, The results in the present study indicate that some transition like the glass transition in the non-crystalline polymers takes place around t′g.