Fabrication of highly transparent ZnO/PVB nanocomposite films with novel UV-shielding properties

High dispersion of nanoparticles in transparent polymer matrices is the prerequisite to maintain the transparency of matrices. However, it is hard to fabricate the nancomposites with high visible light transmittance even at low nanoparticle concentrations. In this work, highly transparent Polyvinyl Butyral (PVB)/ZnO nanocomposites were fabricated by using the two-step process. Firstly, the monodispersed masterbatches were obtained by spray drying of the ZnO monodispersion via our phase-transfer technology and polymer solution in ethanol. Secondly, the transparent ZnO/PVB nanocomposites were prepared by melt extrusion processing. Results indicated that ZnO nanoparticles were homogeneously dispersed in the PVB matrix of aggregates size less than 20 nm, resulting in highly transparent PVB nanocomposites with 99% visible light transmittance (550 nm wavelength), which is as high as that of the system without ZnO nanoparticles. And when the ZnO content was 1 wt%, the nanocomposites could shield 97% UV light (360 nm wavelength). In addition, the tensile strength and the elongation at break of the nanocomposite sample filled with 0.8 wt% ZnO were improved by about 8.3% and 8.2%, respectively.