Applied Mechanics and Materials Vol. 525

Abstract: Polyurethane is a very versatile polymer but it has poor thermal resistance and mechanical resistance. Thus, clay was added in the polyurethane and the thermal properties are determined by a bomb calorimeter. There were two type of clay used which are treated clay and untreated clay. Clay (treated and untreated) was added into polyurethane by Thermal Haaka by extrusion process. In the research, treated clay showed according to the references statement. Addition of 5wt% of treated clay reduced 85% of the heat combustion of the polyurethane while for untreated clay the reduced heat combustion is not too significant. This is because the sensitivity of the bomb calorimeter to the surface area that contacted to the ignition wire. Treated clay certainly can reduced the heat of combustion to 85% of polyurethane with additional of 5wt% of treated clay.

Abstract: The synthesis and characterization of TiO₂ nanostructure has become intensive nowadays because of its superior properties among other semiconductor materials. In this work, TiO₂ nanostructures have been derived from ilmenite mineral by using precipitation technique with various pH and calcination temperature. The resulting nanostructures were characterized to investigate the effects of those variables on the phase, crystallite size, and band gap energy. The characterization was performed by using XRD, FT-IR, UV-Vis DRS, SEM, EDS, and TEM. The results showed that TiO₂ sample prepared under low pH value of 0.3 demonstrated porous structures although they are not well-ordered yet, while the sample with a pH adjustment up to 7.0 provided nanotube structure. The biggest crystallite size of 3.43 nm and low band gap energy of 3.07 eV was obtained in the TiO₂ samples synthesized without pH adjustment and calcined at a a temperature of 300°C. This characteristics shows that TiO₂ nanostructure in this study is potential for the applications of dye sensitized solar cell (DSSC) and photocatalysist.

Abstract: ZnO nanoparticles have been used for many applications, including in cell labeling application. Its light emission can be used to determine and identify biology cells. Wet chemical precipitation method has been successfully done to synthesize the nanoparticle and it was subsequently continued by encapsulating with silica to keep ZnO stabilized in water to be properly used in cell labeling application. Varying precipitation temperatures has been performed to control the nanoparticle size and the addition of F127 surface active agent was carried out to prevent the agglomeration. The results showed the smallest nanoparticle (3.49 nm) was obtained from the process with temperature of 25oC, with the highest band gap energy, 3.12 eV. On the other hand, the largest nanoparticle (13.16 nm) was obtained from synthesis at temperature of 65oC, with the lowest band gap energy, 3.08 eV. These levels of band gap energy are potentially suitable for cell labeling application.

Abstract: A thin cylindrical tube model was established. Its energy absorption property was analyzed when crushing through finite element method. Then its validity was verified through the corresponding experiment. On the basis of the above research, two different material tubes were selected which were aluminum alloy 6060 and cold-roll steel B340LA. Considering the mechanical performance of these two materials might change during dynamic crushing, so the tubes were crushed in three modes including low speed, medium speed and high speed. In order to predict the wall thickness of the two different material tubes when their energy absorption was equal, two methods were proposed which were overall energy method and the stress-strain energy method. Then get the mass ratio of the two different material tubes when they absorbed equal energy. The results showed that the mass of aluminum alloy 6060 tube was about 86%-90% to B340LA tube when they absorbed equal energy. More than 10% lightweight effect could be obtained when cold-roll steel B340LA tube was instead with aluminum alloy 6060 under the condition of their absorbing equal energy.

Abstract: In this research, SrTiO₃ powder is prepared by hydrothermal synthesis method. In the process of reaction, SrCl₂ and Ti (OC₄H₉) ₄ with NaOH can obtain the precursor as reactants and mineralizer respectively. Then take the precursor into autoclave without any pretreatment, to make it react under the temperature of 150 °C and the stirring speed 360 r/min in 8 hours. After the reaction finishing, the prepared SrTiO₃ powder were charactered by X-ray diffraction and SEM. the results of experiment showed that we succeed in making nanostrontium titanate powder under above condition and the grain size is almost 60 nm.

Abstract: Recently, interest in the study of processes occurring in the optical breakdown on the surface of solid targets associated with the increasing number of practical applications of the laser spark, such as laser induced breakdown spectroscopy and micro-and nanomaterials processing. One of the most important tasks - to reduce the diameter of the focal spot, because the size of the modifications directly related to it. However, it is not the only problem faced by the transition to sub-micron range modifications.

Abstract: Low-temperature heat capacities of butyl 4-hydroxybenzoate have been measured by a high precision automated adiabatic calorimeter over the temperature range from 79 to 399 K. The melting temperature, the molar enthalpy and entropy of the phase transition were determined to be (342.227 ± 0.054) K, (26.122 ± 0.192) kJmol^-1 and (76.33 ± 0.55) JK^-1mol^-1.The thermodynamic functions (H_T -H_298.15K) and (S_T- S_298.15K) were calculated in the range from 80 to 400 K with the interval of 5 K. The constant-volume energy and standard molar enthalpy of combustion have been determined, _cU (C₁₁H₁₄O₃,s) =-(5760.30 ± 2.70) kJmol^-1 and _cH_m⁰ (C₁₁H₁₄O₃, s) =-(5765.26 ± 2.70) kJmol^-1, by means of a precision oxygen-bomb combustion calorimeter at T = 298.15 K. The standard molar enthalpy of formation has been derived, _fH_m⁰ (C₁₁H₁₄O₃, s) =-( 564.16 ± 4.41) kJmol^-1, from the standard molar enthalpy of combustion in combination with other auxiliary thermodynamic quantities through a Hess thermochemical cycle.

Abstract: A new complex [Na (H₂O)₂]₆[MoCo₆O₁₂(H₂O)₁₂]·4.3H₂O(s) was synthesized and determined by X-ray crystallography. Low-temperature heat capacities of the compound was measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 380 K. An obvious dehydration process was found in the heat capacity curve of the title compound. The temperature, enthalpy and entropy of the dehydration process were determined to be (370.266±0.292) K, (187.455±0.354) kJ·mol^-1, (50.627±0.078) J·K^-1·mol^-1 by three series of repeated heat capacity measurements in the region of thermal decomposition.

Abstract: BET (Brunauer Emmett and Teller) surface area and pores distribution for the samples DX 09 Carbon were measured for of DX 09 carbon by N₂ adsorption (195 °C) with Autosorb-1C (American Quantachrome Company).The adsorption of benzene over DX 09 Carbon was measured in the static vacuum adsorption equipment, which was self-constructed in laboratory. It was experimentally found that the BET surface area is about 1008 m²/g, and the structure coefficients for DX-09 carbon were W=0.365 and B=1.32*10^-6 measured by benzene adsorption and calculated by D-R equation.

Abstract: Nanometer-sized gold particles supported on Cerium Oxide (CeO₂) were prepared by the method of deposition-precipitation. These catalysts exhibited good activity for the combustion of formaldehyde and the factors affected the activity of the catalyst were observed. The results showed that CeO₂ powder prepared by Ce (NO₃)₃.6H₂O and citric acid were small and gold can disperse on CeO₂ easily. 1.83wt% Au/CeO₂ exhibited the highest activity when velocity of 0.37% formaldehyde was 0.5L/min and corresponding contact time between gas and catalyst was 2h. Formaldehyde removal ratio after treating was up to 80% at 80°C and complete burn-off of formaldehyde was achieved at 120°C. The XRD and TEM results indicated that nanogold particles (≤20nm) were dispersed on cerium oxide homogeneously.