Papers by Author: Xiang Zhang

Abstract: An inorganic salt complex which had a strong ability to generate lot of inert gases rapidly in a fire was prepared. Fire extinguishing agent added with sodium tungstate as a synergist had a great performance in gas release. Flammable gas and oxygen in fire could be diluted by Carbon dioxide and ammonium which released from the heating of inorganic salt complex.

Abstract: In this paper, the influence of catalytic on the extinguishing effect of inorganic salt fire extinguishant has been studied. Results of TG test and burning test indicated that catalytic synergist ammonium tungstate and sodium tungstate can effectively increase the fire extinguishing effect of the inorganic salt fire extinguishant, and sodium tungstate has a better catalytic synergistic effect than ammonium tungstate.

Abstract: This paper focused on the evaluation of burning performance of the traditional organic insulation materials for external wall of building, such as XPS, EPS and PU foam. Results of full-scale fire testing showed that if the LOI of organic materials reach Class B2 requirements, and the organic insulating layer has been protected by thin plastering, then the fire will not spread during the full-scale practical fire testing.

Abstract: This paper focused on the evaluation of burning performance of the traditional organic insulation materials, such as XPS, PU and phenolic foam. Cone calorimeter test indicated that PU showed a well flammability. After the combustion process, most of the XPS was melted, and most of the phenolic foam was burned. SBI test showed that the burning grade of XPS, PU and phenolic foam insulation board are in the region of grade B to Grade D, can not achieve grade A. All XPS samples can reach to level ZA3, however, some PU and phenolic foam samples can not reach to level ZA3.

Abstract: The crystallization behavior of n-HA/PA66 biocomposites at different processing pressure and annealing temperature were investigated by XRD and DSC. The results showed that increasing annealing temperature would weaken the crystalline intensities of pure PA66 and its composites. For n-HA/PA66 composites, the peaks of α1 crystals of PA66 disappeared, only α2 crystals existed, and with the increase of injection pressure and annealing temperature, the crystalline intensity of PA66 decreased. The degree of crystallinity (Xc) of PA66 in composites increased with the increase of injection pressure, however, annealing temperature had no obvious effects on crystalline degree. The mechanical properties had close relationship with the crystallization behavior of the materials.

Abstract: Porous n-HA/PVA hydrogel composite was prepared through in-situ hydrothermal treatment under normal pressure and emulsion foam freeze-drying method, which was used to fabricate porous hydrogel. The pores exhibited interconnection-pore structure owing to the injection of air bubbles and the removal of emulsifier (OP). The porous hydrogels were investigated by using IR, XRD, TEM and SEM. The results indicated that n-HA in the composite could disperse uniformly, and there were chemical bonding with PVA. In addition, nano-hydroxyapatite existed in the composite in the shape of short-rod. The pores were interconnection with narrowly pore size and highly porosity. And the pore size and size distribution were influenced by the weight of OP. The emulsion foam freeze-drying method can be used to prepare porous hydrogel scaffold for tissue engineering, or to contain proteins scaffold, because of operating at a low temperature. The method displayed a vast potential of applied foreground.

Abstract: The compatibility efficiency on different compatibilizer for nano-hydroxyapatite (n-HA) reinforced polyamide 66 (PA66) and high density polyethylene (HDPE) blends at a composition of 40/42/18 as functionalized biomaterial was investigated by mechanical properties testing and scanning electron microscopy (SEM). The results showed that mechanical properties of compatibilized blends were much improved by the compatibilizers of maleic anhydride grafted polyethylene (PE-g-MAH) and ethylene/methacrylic acid ionomer-sodium ion (ION) compared with the uncompatibilized blends. Blends had peak mechanical values of different compatibilizer. Both PE-g and ION formed adhesion during melt mixing and stabilized the morphology and significantly reduced the size of dispersed PE phase. PE-g gave the blends with PE spheres ranging from 1 to 4µm and ION with well-dispersed spheres with an average diameter of 1µm. The more enlarged interphase of the blends containing ION reduced the lower interfacial energy to increase the miscibiliy of the blends. Consequently, ION had better contribution to rigidity properties than PE-g for n-HA/PA/PE blends.

Abstract: In this paper a series of silver ions-substituted hydroxyapatites (HA) were prepared. The antibacterial activities of these materials on textiles against bacteria have been investigated. Titania (TiO2) was selectively added into the materials to decrease the silver-ions concentration to get the same active antimicrobial effects. The microstructure, the shape and size, concentration of silver, and the groups of the composite materials were characterized using transmission electron microscopy (TEM), infrared spectroscopy (IR), Atomic absorption spectroscopy (AAS), and X-ray diffraction (XRD). The results showed that there was a dose dependent-effect of silver-ions concentration from the disk diffusion test. The higher the silver-ions concentration, the better the antibacterial activity of the composite materials was. Keeping silver-ions concentration constant, the antibacterial activity of the materials for adding Titania was better than that of without Titania. Moreover, the addition of Titania would inhibit the discolouration of the composite materials. The antibacterial activities of the composite materials differentiate to some extent with the bacterial strains.