Effect Of Doping Nano-TiO₂ On The Properties Of Polystyrene

To enhance the dispersity and the consistency of nano-TiO2, the surface organic modification of nano-TiO2 particles with LICA38 was studied in this paper, a cross-cut test was employed to optimize the process of pretreatment in order to confirm the best craft parameter. And the technology of doping nano-TiO2 in polystyrene with free-radical polymerization was also studied. DCA, XRD, FTIR, TEM, XPS, TG, DSC, EDX and GPC measurements were used to analyze the effect of pretreatment, the surface morphology, elements and performance of the specimen. The tensile tests for the PS doped nano-TiO2 were also discussed. Results showed that the dynamic contact angle of nano-TiO2 treated with LICA38 was bigger than nano-TiO2 untreated, which indicated that chemical adsorption was occurred between LICA38 and the surface of nano-TiO2. The oil-solubility of nano-TiO2 was enhanced and the dispersion of nano-TiO2 was improved. The results of cross-cut test indicated that the higher reaction temperature, the longer reaction time and proper coupling agent consumption were favorable to obtain better coupling effect. The pure PS that polymerized at 80℃ for 6 hours, then polymerized at 160℃ for 10 hours, with 0.25 wt % coupling agent, has not only higher molecular weight but also better tensile performance.Nano-TiO2 treated with LICA38 could exist with the size of nanometer in PS matrix, and the dispersion of nano-TiO2 was homogeneous, which improved the tensile strength of PS doped with nano-TiO2 obviously, and nano-TiO2 could contribute to improve the tensile performance of PS when only a certain content nano-TiO2 was doped in PS. Thermal performance test indicated that the thermal decomposition temperature of PS doped with nano-TiO2 was higher than that of pure PS, and the glass transition temperature of PS doped with nano-TiO2 was improved. Nano-TiO2 did not hindered polymerization, and the increasing free-radicals of PS had greater activation after they adsorbed to nano-TiO2 surface, so the molecular weight of polymer was heightened.