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

Abstract

The crosslinking processes of aqueous poly(vinyl alcohol) (PVA) by γ-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 ([η]), molecular weight (Mw), hydrodynamic radius (Rh), and radius of gyration (Rg), and a decrease in second virial coefficient (A2) were observed after γ-ray irradiation. However, both the values of [η] and A2 for irradiated PVA fell below the data of unirradiated PVA solutions, suggesting a conformational change of PVA chains after γ-ray irradiation. This structural change of PVA as a result of γ-ray irradiation was also indicated by the decreases in RgRh from 1.5 to 1.39 by SLS and DLS, and in Mark-Houwink exponent αη from 0.54 to 0.26 by SEC-Viscometry. The broadening of the Mw distribution (MWD) as indicated by the polydispersity index increased from 2.2 to 6.5 because of γ-ray irradiation.