Preparation And Modification Of TiO₂ Nanorods And Their Application In PLA And PET

Nano titanium dioxide（TiO₂） has been widely used in the fields of polymer modification, air purification, wastewater treatment because of its small size, large specific surface area, strong ultraviolet shielding ability and high catalytic activity. In this thesis, rutile TiO₂ nanorods were prepared successfully. The effects of surface modification and content of nano TiO₂ on the structure and properties of poly（lactic acid）（PLA） and polyethylene terephthalate（PET） were studied. Several main conclusions were obtained:1. Under normal pressure and low temperature, a large number of rutile-type TiO₂ nanorods were synthesized from cheap and safe titanium source（titanium trichloride） by using the ferric chloride as crystal modification controlling agent. The average length of the obtained TiO₂ nanorods was about 50 nm, and the average diameter was about 8 nm.2. In order to prevent the agglomeration of nano TiO₂ and eliminate the unfavorable catalyzing effect in the polymer matrix, the surface of nano TiO₂ were grafted by twelve alkyl group（WD10-TiO₂）. The grafting amount was about 6%. Nano TiO₂ was coated with SiO₂ during the hydrolysis of tetraethoxysilane（SiO₂@TiO₂） and the thickness of the coating layer was about 4 nm.3. PLA/（SiO₂@TiO₂） nanocomposites were prepared by melt blending. The SiO₂@TiO₂ nanoparticles dispersed well in the PLA. The PLA containing SiO₂@TiO₂ exhibited higher thermal decomposition temperature and crystallization temperature, indicating the heterogeneous nucleation effect. The PLA/（SiO₂@TiO₂） film had excellent UV shielding property while maintaining high visible transmittance. The degree of orientation and crystallinity of PLA/（SiO₂@TiO₂） nanocomposites stretched at 90 oC and 100 oC were higher than those of PLA.4. PET/TiO₂ nanocomposites were prepared by in-situ polymerization. The results showed that the nano TiO₂ dispersed well in PET. While the sample was yellow because of the catalytic effect of nano TiO₂. Therefore, the processing of melt blending was selected for the preparation of PET/TiO₂ nanocomposites. Nano TiO₂ had little effect on the thermal stability and crystallization behavior of PET. Nano TiO₂ accelerated the UV aging of PET, while SiO₂@TiO₂ and WD10-TiO₂ enhanced the anti-light aging properties of PET.