Advanced Materials Research Vols. 284-286

Abstract: Al₂TiO₅-Si₃N₄ composites were fabricated by mixing 75-95% premixed powder, composed of titanium dioxide, α-Al₂O₃ powder, and suitable amount of stabilizing agents such as MgO, SiO₂ and ZrO_2, and 5-25% α-Si₃N₄ and being sintering at 1450-1550°C in nitrogen atmosphere. The effects of Si₃N₄ content, sintering temperature and soaking temperature on the properties of Al₂TiO₅-Si₃N₄ composites were investigated. The results showed that the optimum formula for Al₂TiO₅-Si₃N₄ composites was 90% premixed powder and 10% α-Si₃N₄. The optimum technological parameter was that sintering time was 1550°C for 2h.

Abstract: Two grades of epoxidized natural rubber (ENR), namely, ENR 25 and ENR 40 were mixing through adding 0-5 phr calcium stearate. The effect of calcium stearate concentration on cure characteristics of ENR was studied. The cure properties were determined by Moving Die Rheometer (MDR 2000) at 150°C. It showed that the scorch time (T_S1) for ENR 25 and ENR 40 increased to a maximum value at 1 phr of calcium stearate, and further addition of calcium stearate maked it decrease. The cure time (T₉₀), maximum torque (M_H) and torque difference (M_H﹣M_L) of ENR decreased with increasing calcium stearate loading. For a fixed calcium stearate concentration, the scorch time (T_S1) and cure time (T₉₀) of ENR 40 were shorter than that of ENR 25, which is attributed to the activation of an adjacent double bond by the epoxide group in ENR. The results indicate that the effect of calcium stearate concentration on the cure characteristics of epoxidized natural rubber is remarkable.

Abstract: The Composite based on CIIR and variable sulfur/accelerator ratio were prepared by compounding and vulcanizing process. Tensile properties and dynamic mechanical properties of CIIR were studied. The results indicate that tensile strength and loss factor are influenced by sulfur/ accelerator ratio. Tensile strength and modulus are improved with increasing sulfur/accelerator ratio while loss factor decrease with increasing sulfur/ accelerator ratio.

Abstract: Liquid crystal polymer is widely used in field of manufacturing of equipment parts because of its excellent performance of injection molding and special physical properties. Based on related research and discussion on properties of liquid crystal polymer, we proposed in this paper its properties of high impact resistance, hear, transparency, anti-water/gas, and microwave penetration, which make it widely concerned in field of packaging materials. We can foresee the high possibility of developing new markets with the rapidly expanding range of applications of liquid crystal polymer.

Abstract: Both the performance and lifetime of battery pack are substantially reduced in the cold temperatures, and it influences the performance and cost of electric vehicle strongly. Reasonable and effective heating system becomes very critical for solving the problem. This paper introduces the research development of heating system in the world, including the primary cause of the poor performance of battery pack at cold temperatures and heating of batteries, analyses the methods of heating that have been used or are researching. The limitation of current heating systems is pointed out for the future research.

Abstract: The polyurethane foam as a representative nonaqueous reacted polymer grouting material has become one kind of advanced comprehensive performance material, and therefore it is necessary to research on its anti-permeability properties. According to impermeability grade method, polymer grouting materials are tested under different initial pressures and different densities. The results indicate that the density of polymer materials is generally at the range of 0.1g/cm³～0.3g/cm³ and the initial seepage pressure is at the range of 0.3～0.7MPa, which can bear 30 to 70 meters head pressure when seepage grouting is carried out in hydraulic engineering. According to the actual needs of different projects, polymer grouting amount is controlled to regulate the density of polymer materials to meet the need of different projects impermeability.

Abstract: The core-nanoshell composite materials doped with Nd were prepared by a solid-state reaction method. The core is magnetic fly-ash hollow cenosphere, and the shell is the nanosized ferrite doped with Nd. The thermal decomposition process of the sample was investigated by TG- DTA. The morphology and composition of the composite materials were investigated by the X-ray diffraction analysis ( XRD ), scanning electron microscope ( SEM ) and energy disperse spectroscopy ( EDS ). The results of vibrating sample magnetometer ( VSM ) analysis indicated that the exchange-coupling interaction happens between ferrite of magnetic fly-ash hollow cenosphere and nanosized ferrite coating. The exchange-coupling interaction enhances magnetic loss of composite materials. The results show that doped with Nd can enhance the coercivity too, so the magnetic properties could be promoted further. The magnetic properties of the core-nanoshell composite material are better than that of single-phase.

Abstract: Due to the lack of trifunctional polypropylene oxide (TPPO) certified reference material (CRM) with precise molecular weight on the market, it is therefore very important to prepare such CRM to calibrate the molecular weight testing equipments, and assure the quality in polyurethanes manufacture. In this paper, the certification of TPPO CRM was introduced based on the size-exclusion chromatography with a multi-angle laser light scattering (SEC-MALLS) method and end-group analysis method. First, TPPO was synthesized via controlled ring-opening polymerization of propylene oxide in the condition of both high temperature and pressure using double metal cyanide (DMC) complexes as catalyst, and TPPO oligomer as coinitiator. Then, the molecular weight homogeneity of TPPO CRM was evaluated by using the F-distribution model, and the storage stability of the molecular weight of TPPO CRM was assessed. All potential uncertainty factors for the certification of TPPO CRM were evaluated using cause-effect diagram. The results showed that the chemical structure of TPPO CRM was an anticipatory structure, which was confirmed by IR. The molecular weight homogeneity of TPPO CRM was qualified. The storage stability period of the final product was one year with respect to its molecular weight, and the certification results of TPPO CRM obtained by SEC-MALLS and end-group analysis were 4996±162 and 5025±146, respectively.

Abstract: The tensile stress-strain relationship of rubbers is fairly linear and can be used for obtaining tensile modulus E. In this work we analyzed the tensile stress-strain relationship of filled rubber experimentally and employed the extended 2D homogenization method to compute the modulus of the carbon black (CB) filled rubbers with various CB volume fractions ranging from 5% to 25%. The results reveal that the modulus of CB-filled rubbers increased with the increase in CB volume fraction and in CB aggregation.

Abstract: 3D modle of spreading platform of rapid prototyping machine for ceramic parts is established in PRO/E, and the modle is input to ANSYS, and the finite element analysis modle of the spreading platform is established by plane elemet; According to the structural strength of the experimental condition, considering the gravity of spreading platform to get the splatform’s stress annlysis and structure deformation in the different working conditions. And the dagenrous section is identitied to provide evidence for the further research, and aslo to provide a reference for other similar products.