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Irradiation effects in poly(ethylene oxide)/silica nanocomposite films and gels



Poly(ethylene oxide)/silica (PEO/SiO2) nanocomposite films were modified, and nanocomposite gels were prepared by γ-irradiation up to 100 kGy. Thermal analysis, optical microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy revealed that the outcome mostly depended on the state of the PEO matrix on irradiation and that the state of the sample had a bearing on the effect of nanosilica addition. In unirradiated films, nanosilica induced heterogenous nucleation and increased crystallization temperatures proportional to its content. On irradiation of nanocomposite films, degradation prevailed, resulting in an increased crystallinity of samples irradiated to 50 kGy and a significant deterioration of mechanical properties at higher doses. In films irradiated in air, nanosilica did not provide radiation resistance. It enhanced oxidative degradation by increasing the content of a more radiation sensitive amorphous phase and probably facilitated the crystallization of broken chains resulting in an additional crystallinity increase. In the same dose range, the irradiation of PEO/nano-SiO2 aqueous solutions produced cross-linked nanocomposite gels of much lower crystallinity and phase transformation temperatures and better mechanical properties. Interactions and radiation-induced effects in nanosilica likely contributed to a further crystallinity reduction in nanocomposite gels. Pronounced changes on the addition of 20 wt% of nano-SiO2 to both nanocomposite films and gels indicate a possible synergism of γ-irradiation and nanoparticle addition. POLYM. ENG. SCI., 53:2318–2327, 2013. © 2013 Society of Plastics Engineers