Study On Improving Polystyrene With Nanometer Titania

Nanocomposites have been the subject of active studies due to their unique physical and chemical properties. It is of great significance for the development of high-performance and multi-functional materials.The nano-TiO₂ prepared by sol-gel were reacted with silane coupling agent, and the surface of alklaed-TiO₂ partilces were covered with PS by dispersion polymerization, then the PS/TiO₂ nanocomposites were prepared via the melt blending method. Some of the properties of modified and unmodified nano-TiO₂ and polystyrene/TiO₂ nanocomposites were characterized by FTIR, DTA-TG, SEM, XRD and TEM. The results show as follows:It was shown that KH570 and polystyrene (PS) had been grafted on the surface of TiO₂ particle and the grafting ratio was about 70wt%. The macromolecule of polymer graft to TiO₂ formed core-shell structure in which the modified TiO₂ were wrapped. The optimal technological conditions were as follow: St monomer concentration was 15wt%, initiator dosage was 0.1g, reaction time was 12h and reaction temperature was 70℃.The mechanical properties of polystyrene were enhanced though doping nano-TiO₂ at lower loading. The PS/TiO₂-g-PS composites had higher tensile and impact strength than PS composites filled with TiO₂-KH570 or untreated TiO₂, and the optimal properties were achieved at 1wt% of TiO₂. The tensile and impact strength of PS/TiO₂-g-PS composites, compared to pure PS, were increased by about 43.6% and 90.3%.There was little change of rheological property of PS/TiO₂-g-PS compared to pure PS, but the processing performance of PS composite filled unmodified TiO₂ and TiO₂-KH570 got worse.The thermal stability of the composites was enhanced with increasing TiO₂ content, and the optimal properties were achieved at 1wt%. The thermal stability of the composites was also improved by increasing interface compatibility between TiO₂ and PS matrix.