The thermal degradation behaviour of polyacrylate and its zinc oxide composites were investigated by differential scanning calorimetry (DSC), thermogravimetry (TG) and Fourier transform infrared spectroscopy (FTIR). Reaction mechanisms of polymer degradation with and without ZnO particles were obtained. Filler-free polyacrylate exhibited one DSC peak, indicating that the polymer was degraded with only one stage of weight loss. Polyacrylate/ZnO composites underwent two minor weight losses as well as the major weight loss. ZnO stabilized or destabilized the polymer molecules according to the temperature region. Two mechanisms were proposed for the change of thermal properties of the nanocomposite. An increase of the stabilization or destabilization effect of ZnO nanoparticles was found in the nanocomposite with a higher content of the inorganic phase. Compared to micron ZnO particles, ZnO nanoparticles exhibited a greater effect due to their high specific area giving more sites for interactions. In addition, kinetics of thermal degradation of filler-free polyacrylate and polyacrylate/ZnO composite were quantitatively obtained by means of non-isothermal weight loss data analysis.

Silicon nitride (Si3N4) powders were synthesized with silica sol, urea and carbon black by ammono sol2gel processing. Urea was dissolved in water and mixed homogeneously with silica sol. Ammonolysis of the aqueous solution could form a precursor, which was then mixed with carbon black and nitrided at 1300～1600℃under a flowing N2 atmosphere. The precursor and final powder were characterized by X-ray diffractometry, infrared spectroscopy and transmission electron microscopy. Results showed that Si3N4 powders with a size of 50～80nm and a content of more than 37% nitrogen can be obtained from the precursor annealed at 1500℃under a N2 flow of 3L/min for 2h. Effects of ammonolysis and synthesizing conditions on the final products were investigated.

The colloidal stabilization of nano-sized zinc oxide suspensions with maleic anhydride sodium salt copolymer is examined to understand the primary mechanism of dispersion. FTIR spectroscopic data provided evidence in support of hydrogen bonding and chemical interaction in the case of the MA-Na copolymer/ZnO system. The suspension stability was characterized by sedimentation tests and TEM method. The copolymer was found to stabilize the suspension of ZnO nanoparticles through electrosteric repulsion. Influences of factors such as pH and the copolymer concentration on the colloidal stability of aqueous suspension were investigated. The copolymer at high pH of the solution provided more effective degree of sustained particle dispersion. The adsorbed MA-Na copolymer provided a good stabilization under the saturated adsorption amount, while the excess copolymer flocculated the dispersed system.

本文对原位反应合成的C-SiC-TiC-TiB2复合材料在600-1200℃空气中的抗氧化性进行了研究。在不同材料组成和试验温度下，试样分别出现氧化增重和失重，这主要取决于碳相和陶瓷相的氧化速率及氧化层的结构特征。在600℃该材料几乎不被氧化；800℃时，TiB2被优先氧化，形成B2O3液相；在1000℃以上，B2O3与SiO2生成硼硅酸盐玻璃，形成一致密氧化层。氧化过程中液相的出现和致密氧化层的形成显著降低了氧化速率，使材料进入钝氧化，从而大幅度地提高了该材料的抗氧化能力。

The adsorption of poly(acrylic acid) (PAA) in aqueous suspension onto the surface of TiO2 nanoparticles was investigated. FTIR spectroscopic data provided evidence in support of hydrogen bonding and chemical interaction in the case of the PAA–TiO2 system. Adsorption isotherms demonstrated that part of the PAA initially added to the suspension was adsorbed onto the TiO2 surface, after which there was a gradual attainment of an adsorption plateau. The adsorption density of PAA was found to increase with an increase of PAA molecular weight, while it decreased with an increase of pH. The thickness of the PAA adsorption layer was calculated based on measurements of suspension viscosities in the absence and presence of PAA. It was shown that the thickness of the adsorption layer increased with the increase of pH, PAA molecular weight, and its concentration. The surface charge density, the diffuse charge density, and the zeta potential of TiO2 varied distinctly after PAA adsorption. The shift of pHiep toward a lower pH value was observed in the presence of PAA. PAA was found to stabilize the suspension of TiO2 nanoparticles through electrosteric repulsion. The influence of factors such as PAA molecular weight and its concentration on the colloidal stability of the aqueous suspension was also investigated.