Viscometric, light scattering, and size-exclusion chromatography studies on the structural changes of aqueous poly(vinyl alcohol) induced by γ-ray irradiation

dThe crosslinking processes of aqueous poly(vinyl alcohol) (PVA) by gamma-ray irradiation were studied by viscometry, dynamic and static light scattering (DLS and SLS), as well as size exclusion chromatography (SEC). Increases in the intrinsic viscosity ([eta]), molecular weight (M-omega), hydrodynamic radius (Rh), and radius of gyration (R-g) and a decrease in second virial coefficient (A(2)) were observed after gamma-ray irradiation. However, both the values of [eta] and A, for irradiated PVA fell below the data of unirradiated PVA solutions, suggesting a conformational change of PVA chains after gamma-ray irradiation. This structural change of PVA as a result of gamma-ray irradiation was also indicated by the decreases in R-g/R-h from 1.5 to 1.39 by SLS and DLS, and in Mark-Houwink exponent alpha(eta) from 0.54 to 0.26 by SEC-Viscometry. The broadening of the M-omega distribution (MWD) as indicated by the polydispersity index increased from 2.2 to 6.5 because of gamma-ray irradiation. (C) 2000 John Wiley & Sons, Inc.