Why the wavelength of the absorption edge of PS (polystyrene) is in the ultraviolet wavelength range regardless of the mass fraction of ZnO nanoparticles ? Same in case of PS/ZnO nanocomposites. Anyone can explain
Polymer matrices such as polystyrene, polyesters and... are absorbers of ultraviolet rays, the absorption of which can lead to the destruction and failure of bonds in these polymers. Therefore, the absorption edge of polystyrene is in the range of ultraviolet wavelength range. The absorption edge of zinc oxide is also in the range of ultraviolet light.
Dear Monika Barala , the explanation by Fateme Moosavi clear and accurate, your composite is made of two components which do not absorb into the Visible region of the spectrum. Both, the composite matrix (PS) and the composite load (ZnO nanoparticles) show absortion just into the UV region. It is true that PS absorbs at deeper UV than ZnO, which has an absorbtion maximum at around 375 nm, it is still in the UV region.
Both materials are clear, transparent and colorless in bulk. Colorless means they do not absorb into the visible region. Mixing two colorless materials is not going to cause appearance of coloration, unless some chemical reaction happens between the components.
When you increase the fraction of ZnO nanoparticles they could, at some point, aggregate to form larger particles able to cause light scattering, which will cause the composite appears somewhat cloudy or whitish, but without colour.
Hope this helps. Good luck with your work and best wishes.
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