Ziming Wang

Preparation and characterization of nanostructured Ni(OH)2 and NiO thin films by a simple solution growth process

Nanostructured Ni(OH)2 thin films were prepared by a simple solution growth process with F(-) and NH3 used as Ni2+ coordination agents, and ammonia hydroxide solution used as OH(-) supplier to accelerate the hydrolyzation of nickel complex species. The results showed Ni(OH)2 thin films were constructed mainly with hexagonal beta-Ni(OH)2 nanorods; the F(-) and NH3 in reactive solutions played important roles in the film growth process; and solution pH had great influence on the morphologies of thin films, which was explained by the competition of Ni(OH)2 nucleation and growth in solutions. NiO crystallinity thin films were obtained by annealing Ni(OH)2 thin films at 400 degrees C for 2 h and the morphologies of the Ni(OH)2 thin films were sustained well during the annealed process.

Preparation, Characterization and Performances of Powdered Polycarboxylate Superplasticizer with Bulk Polymerization

A polycarboxylate superplasticizer (PCE) was synthesized in a non-solvent system with bulk polymerization and then was pulverized into powdered form to achieve a rapid transportation and convenient preparation. PCE synthesized by using isopentenyl polyethylene glycol (TPEG) or isobutenyl polyethylene glycol (IPEG) as a macromonomer exhibited the best fluidities and retaining properties at 80 °C and 75 °C, respectively. Besides, azobisisobutyronitrile (AIBN) was suitable as an initiator, and the fumaric acid was suitable as the third monomer. The test results of 1H nuclear magnetic resonance (1H NMR) confirmed the occurrences of polymerization, and the measurement results of molecular weight and distribution showed that PCE molecular weight characteristics were in accordance with their fluidity properties in cement paste. The application performances in cement showed that PCEs with the best paste fluidity retentions had the longest final setting time and the shortest setting time interval, and the PCEs with good fluidity properties can obviously delay the hydration process and lower the hydration heat. Accordingly, this is a novel, energy-saving and economical method to prepare powdered PCE in the field of concrete admixtures.

Performances and working mechanism of a novel polycarboxylate superplasticizer synthesized through changing molecular topological structure

A novel star-shaped polycarboxylate superplasticizer (SPCE) was synthesized through a simple two-step method. 1H Nuclear Magnetic Resonance (1H NMR) and Infrared Spectroscopy (IR) measurements were used for structural characterization. SPCE and comb-shaped polycarboxylate superplasticizer (CPCE) with same molecular weights were designed and synthesized. The cement paste containing SPCE exhibited better fluidity, fluidity retention, water reduction, 25% lower saturated dosage of PCE, 10% longer setting time, lower hydration heat, more delayed hydration heat evolution and lower amount of hydration products at early ages. Furthermore, the adsorption behavior of SPCE and CPCE in cement pastes and the zeta potential were investigated, and then the working mechanism of SPCE was theoretically explained. It is interesting that changing topological structure from comb-shape to star-shape can achieve the optimization of dispersion effect, and further improve the working effectiveness. The aims of this study are to provide a new avenue to synthesize superplasticizer with novel structure achieving the chemical diversity of superplasticizer structure, and to verify the contribution of optimizing molecular shape. This new type of superplasticizer can be used as a rheology modifying agent in fresh cement-based materials.

Research on life cycle CO2 emissions of energy carriers in China

Abstract The purpose of this study is to determine the life cycle CO2 emissions for the production and distribution of energy carriers in China. The mathematical method of input–output analysis was used to model the complicated materials flows between different energy industries. The results show that, for providing 1 GJ fuels, coking products have the largest CO2 emission, followed by oil products, middling coal, cleaned coal, natural gas and crude oil, and raw coal. The results also show that the theory and mathematical model of input–output analysis are more proper for energy carriers than traditional inventory calculation models. The comparison between China and Japan indicates that the life cycle CO2 emissions of energy carriers produced in China are higher than developed level; therefore there is CO2 mitigation potential for China’s energy industries.

Life cycle assessment of beneficial use of domestic waste for cement production in China

Abstract Cement constitutes one of the major materials used for the construction of buildings. In 2011, the cement output of China reached 2·06 billion tons, which accounts for over 50% of the total cement output of the world. Meanwhile, more than 230 million tons industrial waste and domestic waste are beneficial used as raw materials in cement production each year, which results in a decrease in the total raw materials and energy demands and prevents a large amount of land use for landfill or surface impoundment. The objective of this study is to analyze the environmental impact caused by beneficial use of domestic waste in Chinese cement industry. Subsequently, the environmental burdens of five routes of domestic waste treatments, including landfill, incineration, beneficial used by cement production, etc, are quantified one by one using life cycle assessment methodology. The results demonstrate that the beneficial use of domestic waste has a great potential to decrease the environmental impact caused by waste treatment, especially to lower human toxic impact.

Characteristics of Self-Healing Microcapsules for Cementitious Composites

Urea formaldehyde/epoxy resin microcapsules were prepared by an in situ polymerization method and the effect of emulsifier on the syntheses process of the microcapsules was discussed. The surface morphology of the microcapsules was observed by optical microscopy and scanning electron microscopy (SEM). Chemical structure was characterized by Fourier transform infrared spectroscopy (FTIR). Thermal stability was obtained using simultaneous thermal analysis (STA). The microcapsules were composed of urea-formaldehyde resin shell and epoxy resin core. Emulsifier played an important role in the polymerization process when the core material was packed by pre-polymer, so the effects of different emulsifiers (OP-10, SDS and SDBS) were discussed respectively. Results showed that the particle size of the microcapsules was uniform when SDBS as an emulsifier. Microcapsules showed good thermal stability below 240 °C and the initial decomposition temperature of the microcapsules was 265 °C. The core materials released after microcapsules rupturing, which could be proven by the images of SEM. When implanted in cementitious composites, complete shape of microcapsules and good interface between microcapsules and cement specimen substrate could also be observed.

The Influence of Volume Changes in Portland and Calcium Sulfoaluminate Binary Cement

The long-term volume changes of Portland-Calcium sulfoaluminate cement systems has been studied for samples cured under different conditions. Three curing conditions were chosen in this study and the composite cement systems showed different results with different CSA dosages. Progressively higher amount of CSA was added to the composite cement system and it was found that there was a critical dosage of CSA leading to unstable expansion and failure of the samples by curing under water. But in drying condition, the systems showed shrinkage and the degree of volume changes were similar than expansion by curing under water. By selecting the composition of CSA-PC systems and curing conditions, the volume stability of composite cement could be controlled.

Effect of Conductivity and Radiation on Heat Dissipation Performance of Coating

Aiming at the problem of heat dissipation of electronic devices in low temperature environment, the effect of thermal conductivity and emissivity of coating on its heat dissipation performance was studied by theoretical calculations and experiments in this study. The results show that the heat dissipation performance of organic coating with emissivity of 0.7–0.95 is improved as its thermal conductivity increasing. And temperature difference between inside and surface of object is inversely proportional to thermal conductivity. That is, when thermal conductivity exceeds a certain value, it will no longer affect heat dissipation performance of coating. In addition, emissivity of coating directly affects its cooling performance, and the proper matching interaction between thermal conductivity and emissivity of coating can enhance heat dissipation effects. In the case of non-forced convection cooling, the thermal conductivity of the organic coating is preferably 2–10 W/m·K.

Effects of Chain Transfer Agent on the Performances of Branched Polycarboxylate Superplasticizer

A branched polycarboxylate superplasticizer (BPCE) was synthesized via copolymerization of polymerizable active center, isobutenyl polyethylene glycol (IPEG) and acrylic acid (AA). To investigate the effects of chain transfer agent on the performances of BPCE, a series of BPCEs with different molecular weights were further synthesized by changing the addition amount of chain transfer agent, i.e., thioglycolic acid (TGA). The characteristic molecular structures of BPCEs were determined by Infrared Spectroscopy (IR) and viscosity method. Furthermore, the dispersing capacities and adsorption behaviors of BPCEs in cement pastes were probed. The result showed that, the paste fluidity and adsorption amount both presented a trend of first increase and then decrease with the increase of TGA/IPEG proportion, and the maximum appeared at the TGA/IPEG proportion of 0.15 (M = 96314 g/mol). The hydration products of cement pastes containing BPCEs at different curing ages were measured by X-Ray Diffraction (XRD), showing that the introduction of BPCE caused the delay of initial hydration which presented some retardation, and this trend was shown most significantly at the TGA/IPEG proportion of 0.15. The aim of this study is to suggest that moderate dosage of chain transfer agent for the synthesis of BPCE is beneficial to achieve good dispersing and adsorption effectiveness.

Effects of substrate temperature on the microstructure, surface morphology and optical properties of Cu-doped ZnO films

Abstract Cu-doped ZnO films with a single phase (002) oriented hexagonal wurtzite structure were prepared on glass substrates by magnetron co-sputtering. The influences of substrate temperature on the microstructure, surface morphology and optical properties of the films were systematically investigated. We found that increasing temperature can enlarge the crystal grains and improve the crystallinity of the films. The change of deposition temperature can cause the shift of optical absorption line and influence the band gap. These optical effects of substrate temperature can be attributed to the different Cu content in the films.