Materials Science Forum Vol. 724

Abstract: Photodegradable polyethylene films have attracted considerable interests in recently years for its environmental degradability. However, it would be a scientifically and technological challenging issue to assess the degradable process. In order to explore the effect of the photo sensitizer on natural environment degradation characteristics of photodegradable polyethylene film, we investigated the changes of the tensile strength and elongation at break of the PE film (as the control group) and the PE photodegradable film along with the time in the ambient conditions. Photodegradable PE films showed the greater decrement of the tensile strength and elongation at break than that of the control group after 90 days explosion in ambient conditions which indicated its excellent degradability. Thus, the photo sensitizer being used in the PE films could improve the degradability of the PE films in the ambient conditions to a great extent.

Abstract: The increasing use of the PE plastic film means increasing problems of the soil environmental destroy. In order to investigate the effect of PE film degradation products on the carbon dioxide content of soil, degradation products of the PE film with different molecular weight were added in three kinds of soil respectively, and corns were cultivated in the soil. FTIR gas checkout equipment was utilized to monitor changes of the carbon dioxide content of the different soil. A Mathematical model was built with the recorded data to depict variation of the carbon dioxide content. The results showed that the CO₂ content is high in the sandy soil with degradation products of PE plastic films (molecular weight of 5000 Da) . It is also high in the clay soil and loam soil with degradation products of PE (molecular weight of 2000 Da). Compared to the control group (LLDPE), it can be found that small molecular weight PE plastic films have a greater effect on the CO₂ content. Thus, it is deduced that small molecular weight PE plastic films are degradable in the soil.

Abstract: The blend films of ungelatinized and gelatinized starch/polyvinyl alcohol (PVA) were prepared by solution casting method. Their morphologies and thermal properties were analyzed by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). A droplet phase was observed in the blends containing ungelatinized starch and a laminated phase was observed in the blends containing gelatinized starch. For both ungelatinized and gelatinized starch/PVA blends the melting temperature (T_m) (210230) of PVA was detected, and the T_m of gelatinized starch/PVA blends was higher than that of the ungelatinized starch/PVA blends. TGA results showed that over the rst 300 the weight loss for ungelatinized starch/PVA blends was higher than that for gelatinized starch/PVA blends, however the gelatinized starch/PVA blends showed the greater weight loss after scanning up to 400. Different morphologies and thermal properties of two types of blends were attributed to the different hydrogen bonding interactions between starch and polyvinyl alcohol.

Abstract: A laboratory, jar-test type study was conducted to investigate the effect of operational parameters on coagulation efficiency when PACl and ferric chloride are used. Under the same dosages, TP removal by ferric chloride was more effective than that of PACl with municipal fresh sewage, while PACl was superior to ferric chloride in case filtered municipal fresh sewage was used as feed. Zeta potential is believed to be a feasible parameter for the determining of appropriate coagulant dosage. Optimal pH for TOC removal was about 6.0, which is slightly lower than that for turbidity and color removal. There are no significant difference in the removal of TOC, turbidity and color over the range of GT values 12,780~112,800.

Abstract: Because bromic acid ion generated by the ozone processing of drinking water for sterilization is strong carcinogenic, there is a high possibility in persons health hazard. The titanium dioxide was reduced at 900-degree Centigrade by the gas atmosphere (CO or H₂). It was found that the concentration of the bromic acid ion in water was decreased at time when the reduced titanium oxide was added to water including the bromic acid ion. The bromic acid ion in water could be adsorbed by the titanium oxide reduced. In addition, it was suggested that the bromic acid ion could be decomposed into the bromide ion with low carcinogenic by using the photocatalitic function of titanium oxide under UV irradiation.

Abstract: This study was conducted to evaluate the feasibility of using bottom ash after magnetic separation and dredged soil from the coal power plants as raw materials for artificial lightweight aggregate (ALA). The dependence of composition and sintering temperature on physical properties of ALA was investigated. Fe compounds play an important role in the bloating reaction, thus specimens containing more ferrous materials such as Fe₃O₄ are more easily bloated. Both black core region and bloating phenomenon were increased with an increase in the contents of dredged soil. Specimens made use of MBA(Magnetic separated bottom ash which has magnetic components) showed lower bulk density than those of NMBA(non-magnetic separated bottom ash which has much less ferrous materials. It was confirmed that MBA could be used as an effective raw material for making ALA having low density because the ferrous components in it act as bloating agents.

Abstract: The formation of organic-inorganic hybrid composite with ceramic platelets and polymeric compound can have the higher strength and higher elasticity than metal, which is a nanocomposite with high strength and light weight. Ceramic platelet such as Al₂O₃ has been used to form organic-inorganic composite material using PMMA as an organic polymer. Bending strength and density of the composites prepared by infiltration and post-warm pressing were measured. FE-SEM and TG analysis were carried out to determine the microstructure of the organic-inorganic composite materials. Bending strengths and densities of the composites prepared by Al₂O₃ ceramic plate and PMMA after post-warm pressing were ~70MPa and ranged from 2.4 to 2.6, respectively.

Abstract: Manganese silicide is one of the potential thermoelectric materials for high temperature application. As a fundamental investigation on these materials group, manganese monosilicides were synthesized by the mechanical alloying of stoichiometric elemental powder compositions, and the as-milled powders were consolidate by vacuum hot pressing. Phase transformation and microstructure evolution during mechanical alloying and hot consolidation were investigated using XRD and SEM. Near single phase of monosilicides were successfully produced in this process. Thermoelectric properties as a function of temperature were evaluated in terms of Seebeek coefficient, electrical resistivity, thermal conductivity and the figure of merit for the hot pressed specimens. Mechanically alloyed manganese monosilicide, MnSi, appeared to have a potential as a thermoelectric material in this study.

Abstract: The geometric structure, band structure and density of state of pure and Ag-N, Ag-2N codoped wurtzite ZnO have been investigated by first-principles ultrasoft pseudopotential method in the generalized gradient approximation. These structures induce fully occupied defect states above the valence-band maximum of bulk ZnO. The calculation results show that the codoped structure Ag-N has better stability. Meanwhile, the carrier concentration is increased in the Ag-2N codoped configuration where the delocalized features are obvious. Our findings suggest that codoping of Ag-2N could efficiently enhance the N dopant solubility and is likely to yield better p-type conductivity.

Abstract: This research concerns the characteristics of ALA made of magnetically separated desulfurized fly ash (DFA) generated from the coal power plant having fluidized bed type boiler. Being believed that these alkali-rich components could be separated by magnetic separation, desulfurized fly ash was separated by using 10,000 Gauss magnets as magnetic desulfurized fly ash (MDFA) and non-magnetic desulfurized fly ash (DFA). The dependence of composition and sintering temperature on physical property of ALA was studied. It seems to be apparent that the glass phase which is one of the main problems in the ALA manufacturing process could not be controlled by the magnetic separation only, but the formation of pores could be considerably controlled by the magnetic separation. It is also clear that neither DFA nor MDFA can be used as raw materials for making ALA; however, magnetic separation of desulfurized fly ash from fluidized bed type boiler is effective to collect bloating components for self-bloating of ALA without addition of an extra bloating agent.