Structural properties of γ-irradiated poly(vinyl alcohol)/poly(ethylene glycol) polymer blends

The effect of various doses of gamma radiation on the structural properties of water-soluble polymer blends based on poly(vinyl alcohol) (PVA) and poly(ethylene glycol) (PEG) has been investigated. Although the aqueous solutions of individual PVA and PEG homopolymers were homogeneous and clear, films transparent to visual observation were only formed by solution casting of pure PVA and those blends containing low ratios of PEG up to 30%. The structure-property behavior of this range of blends before and after gamma irradiation was investigated by light reflectance and UV absorbance, differential scanning calorimetry (DSC), IR spectroscopy, and tensile mechanical testing. The DSC thermograms of PVA/PEG blends, before or after gamma irradiation, showed a solely endothermic peak over the temperature range 40-140degreesC, which may have arisen from the melting of the PEG component or from the glass transition of PVA/PEG as a miscible blend in accordance with those calculated on the basis of the theoretical Fox equation. Also, these thermograms did not clearly show any transition that arised from the pure PVA component. However, the improvement in tensile mechanical properties of PVA/PEG blends, the reflectance, and the optical absorption measurements support the idea of improved miscibility after gamma irradiation. (C) 2004 Wiley Periodicals, Inc.