LLDPE／nano-SiO2 composites wele prepared by melt-blending

and the mechanical and optical properties of the composites were investigated．The results showed that the elastic modulus of the composites obviously increased with the increase of SiO2 content

and the breaking elongation remained unchanged at low content of SiO2．Both the impact strength and the tensile strength of composites were improved with an increase of nano-SiO2 content and reached maximum when 3 phr nano-SiO2 were introduced．The IR absorptivity (ranging from 7 μm to 11 μm) of the composite films increased dramatically with a small amount of nano-SiO2 introduced．Although the visible light transmittance of the film declined a little compared with the pure LLDPE

the haze value increased much. It was also found that the surface-treatment method of nano-SiO2 has great influence on the optical properties of the composite films．The infrared absorptivity and haze of the composites filled with nano-SiO2 treated by silane coupling agent in ethanol were superior to those of the composites filled with nano-SiO2 treated by silane coupling agent in a ball mill

because the former has smaller particle size and more uniform dispersion in matrix than the latter.