ABSTRACT
In order to promote barrier against ultraviolet radiation and increase of mechanical characteristics performance, nanocomposites of recycled polycarbonate/nano-zinc oxide (rPC/nZnO) with different nZnO content were prepared and submitted to doses of gamma-radiation (1050 kGy). The nanocomposites were also exposed to Xenon light source in a weather chamber viewing to evaluate the action of nZnO against ultraviolet light. The rPC/nZnO nanocomposites were characterized by thermogravimetry (TGA), differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and infrared spectrometry (FT-IR). There was a progressive reduction of the glass transition temperature (T g) and degradation temperatures, T onset and T max, as function of gamma-radiation dose and nano-zinc oxide content. The lowering of the thermal properties was attributed to the alcoholysis reaction between hydroxyl groups onto the nZnO surface and carbonate linkages of the rPC during the molten state. WAXD revealed a possible chains arrangement (induction of crystallinity) and/or segregation of chains size (scission of rPC chains generating oligomers) associated to the alcoholysis reaction. The action of gamma-radiation as crosslinking agent was not effective. The degree of swelling is zero on account of the stabilization of rPC radicals by oxygen during gamma-radiation exposure. Before exposure to UV light the carbonyl index (CI) show trend to decreasecorroborating the scission of the rPC carbonate bonds. After 100 hours of exposure a recovering of the CI was noticed. The result was associated to the free radicals recombination and esterification reactions. In some extent the combined action of nZnO and gamma-radiation as barrier to UV light was successful.
