Nitrogen-doped TiO2 nanocrystalline powders were prepared by hydrolysis of tetrachloride titanium (TiCl4) in a mixed solution of ethanol and ammonium nitrate (NH4NO3) at ambient temperature and a tmosphere followed by calcination at 400 ℃ for 2 h in air. FTIR spectra demonstrate that amine group in original gel is eliminated by calcination,and the TiO2 powder is liable to absorb water onto its surface and into i ts capillary pore. XRD and SEM results show that the average size of nanocrystalline TiO2 particles is no more than 60 nm and with increasing the calcination temperature,the size of particles increases. XPS studies indicate the nitrogen atom enters into the TiO2 lattice and occupies the position of oxygen atom. The nitrogen doping n ot only depresses the grain growth of TiO2 particles,but also reduces the phase transformation temperature of anatase to rutile. The photocatalytic activity of the nitrogen-doped TiO2 powders has been evaluated by e xperiments of photocatalytic degradation aqueous methylene blue.
Melt blends of low-density polyethylene(LDPE), ethylene vinyl acetate(EVA) and coal with various compositions were prepared through reactive extrusion. The rheological behaviour was studied with respect to the effect of blend ratio, shear rate using a rheometer to gain an understanding of processing parameters controlling industrial ap-plication. Compatibility was also evaluated by differential scanning calorimetry(DSC) and scanning electron microscopy(SEM). The results revealed that LDPE/EVA/coal is a partly compatible system showing pseudo-plastic behaviour, increase in viscosity with increased coal content appeares evident only at low shear rate region, viscosity tends to keep consistent approximately but irrelates to coal content at higher shear rate. Blends viscosity and compatibility are attibuted to changes in LDPE crystalline structure and entanglement, together with interaction between macromolecular aliphatic chains in coal and amorphous phase in LDPE and EVA at the boundaries of phases, which comes forth during the rear-rangement process of the crystalline structure.
