Applied Mechanics and Materials Vols. 584-586

Abstract: Nanometer titanium dioxide has not only small size effect, quantum dimension effect, surface and interface effects and macroscopic quantum tunnel effect, but also photocatalytic effect. Vac-acrylate emulsion is one of the important emulsion adhesive. It has good properties for coating, high cohesive strength, no pollution. It has the special functions with few nano-TiO₂.In this paper, method of modification about nanometer TiO₂ was introduced via cellulose sodium. The modified nanometer titanium dioxide was added to the material of the preparation of acrylic emulsion including vinyl acetate, butyl acrylate, acrylic acid and methyl methacrylate to synthesize composite of nano-TiO₂/vac-acrylic emulsion. According to the performance analysis of solid content of emulsion and stabilization, we can find that when the use level of dosage, emulsifier, nano-TiO₂ is 0.5%, 3.2%, 0.7%, and emulsion has the best combination property.

Abstract: In order to obtain an important azobenzene liquid crystal intermediate with phenylacetylene group, Sonogashira coupling reaction was used to preparation the compound. In this paper, the intermediate was synthesized by (4-Iodo-phenyl)-(4-trifluoromethyl-phenyl)-diazene and trimethyl silyl acetylene (TMSA) as raw materials, and then the trimethyl silyl group was removaled under the action of K₂CO₃. During the synthesis, the optimum reaction conditions were obtained, that the mol ratio of (4-Iodo-phenyl)-(4-trifluoromethyl-phenyl)-diazene and trimethyl silyl acetylene was 1:2, the reaction temperature was 80 oC. Fourier transform infrared spectroscopy (FT-IR) was used to measure the molecular structure of the target compound.

Abstract: The influence of the chemical structure both of polymer and plasticizer on the elasticity modulus has been analyzed. Consideration was made of the situation when the plasticized polymer is in the glassy or rubbery state. Description of the glassy state is produced basing on equation [1-2] containing the elasticity coefficient of atom bonds, the characteristic size of the bonds, and Van-der-Waals volumes both of the repeating units of polymers and molecule of plasticizer. Analysis for the rubbery state is based on the classic rubber elasticity theory. As a result the universal relationships are provided for description of the influence of chemical structure both of polymer and plasticizer on the modulus of elasticity.

Abstract: The theoretical analysis regarding the influence of the chemical structures both of polymer and plasticizer on the glass transition temperature has been produced. The analysis is made based on the Askadskii equation allowing T_g calculation of polymers. The phenomenon of blocking polar groups of the polymer by the molecules of plasticizer is taken into consideration. Also the effect of dilution was considered. The analytical expression for concentration dependence of the glass transition temperature is obtained, and a good agreement between the experimental and calculated data is provided.

Abstract: The article sums up post--disaster reconstruction of underground engineering. The post-disaster reconstruction of green concrete construction technology evaluation system was studie. Taking the underground engineering of administrative center of the Beichuan County as an example, the writer conducts a detailed analysis the post-disaster reconstruction underground engineering green concrete constution technology evaluation system research.

Abstract: It is one of the measures of improving durability of concrete structure that apply silicone water repellent on concrete surface. The characteristic of silicone water repellent is to keep the respiratory function of concrete, not to change the original appearance of the concrete, have good hydrophobic performance and can resist to chloride ion penetration. This paper studies the hydrolysis of silicone water repellents solutions with different pH by measuring the electrical conductivity, pH value, and surface tension of the solution. The results show that silicone water repellent is hydrolyzing quickly very much. The hydrolysis time will extend with the increase of the concentration of silicone water repellent. By means of impregnating sand, rubble, cement pieces and calcium carbonate (CaCO₃) powder with silicone water repellents, the water absorption at different temperature and humidity are studied and compared with the same material but not impregnated. The results indicate that the water absorption of impregnated material decreases and the silicone water repellent has hydrophobicity. The higher humidity can help hydrolysis and adhesion of silicone water repellent. The higher temperature may increase water absorption of base materials impregnated with low molecule weight silicone water repellent. Low molecule weight silicone water repellent liquid is residue on the calcium carbonate powder surface.

Abstract: The pass design, hole rates and materials affect the insulation properties of perforated bricks directly. In order to study their effects on the insulation of the perforated bricks, six models was analyzed by the thermal module of ANSYS. The results prove that larger quadrate holes rates lead to better insulation, and the material with small thermal conductivities contribute to large heat transfer resistance value of the bricks. To achieve the energy saving standards, more bricks with lower coefficient of thermal conductivity are to be developed.

Abstract: Selecting rubber powders, which is divided into 80 mesh and 150 mesh, as the research object, to understand the influence of high performance of lower clinker concrete mechanical properties of rubber powder with different varieties and volume. Taking the compressive strength, flexural strength and ratio of flexural strength to compressive strength as an indicator, the thesis explores the influence of the high performance concrete with low clinker, which rubber powder are mixed into as fine aggregate, on the compressive strength bending strength and ductility.

Abstract: Smart behavior of cement based composites containing carbon nanotubes was studied under compression. The results show that the conductivity of the composites is related to the pressure level. For monotonic loading, the electrical resistance decreases correspondingly with increasing stress. For cycling loading, the electrical resistance of specimen varies with repeated loading-unloading. It shows that the electrical resistivity changes recoverability.

Abstract: This paper reports the effects of hydrogen peroxide in surface morphology, strength, density, thermal conductivity of foam concrete and hydrogen peroxide utilization efficiency. The results show that these foam concretes are new and innovative building materials with interesting properties: low mass density and high strength when the addition amount of hydrogen peroxide is in 5%~6% range. Responsible for these properties are the macro-and microporosity. Macropores are created by adding hydrogen peroxide in different addition amount. It is also found that the utilization efficiency of hydrogen peroxide is higher when the addition amount of hydrogen peroxide is in the range of 5%~6%.