抄録
Neutron spin-echo (NSE) measurements have been performed on three types ofpoly (vinyl alcohol)(PVA) gels;two physical gels and one chemical gel.The first onewas a PVA gel in a mixture of deuterated dimethyl sulfoxide (DMSO-d6) and D2O withvolume fraction of DMSO-d6being0.6, in which cross-links are made of crystallites.On the basis of NSE results, small-angle neutron scattering (SANS) intensity wasdivided into static and dynamic fluctuations to find that the static fluctuations weredominant in the present Q range.The dynamic fluctuations are analyzed in terms offluctuations of cross-links in the quasi-equilibrium position.The second one was PVAin aqueous borax solution.The intermediate scattering functions of the gel as well asthe sol were well described by the Zimm mode and the gel mode in Q regions of aboveand below a critical Qc.The last one was the chemically cross-linked PVA gel.Theintermediate scattering function was also described by Zimm mode in a short-timeregion, suggesting that the gel behaves like sol. However, in a long-time region, thedata points deviated from Zimm function, suggesting that the long-time dynamics wasrestricted by the cross-links made of covalent bonds.
