Advanced Materials Research Vols. 834-836

Abstract: A molecular colloidal shear thickening fluid (STF), polyborondimethylsioxane (PBDMS) was synthesized, which differs from traditionally studied Silica/PEG system. Differential Scanning Calorimetry (DSC), the controlled stress rheometer.etc, were used to characterize the produced PBDMS. Scanning Electron Microscope (SEM) is the method to get the surface morphology of the Kevlar fabric impregnated by the fluid. Meanwhile the ballistic and stab tests of the composites materials were investigated.

Abstract: Two kinds of polytetrafluoroethylene (PTFE) composites PTFE/GF/Gr (sample 1) and PTFE/GF/Gr/Cu (sample 2) were prepared by mixed molding method. X-ray diffraction results show that sample 2 is crystal structure, while sample 1 is amorphous/crystal structure. They were processed into the bearing bushes, which were installed on the water pump bearing to study the influence of different structures on friction properties by rotating bearing. Experimental results reveal that the wearing rate of sample 2 is much higher than that of sample 1. From the optical microscope and SEM analysis of the worn surface, it indicates that the wearing mechanism of sample 1 with amorphous structure is adhesive wearing, while that of sample 2 is abrasive and fatigue wearing mechanism. Our results indicate that the PTFE composition with amorphous matrix can be used to sliding bearings because of its ideal self-lubricating properties.

Abstract: Three kinds of combination schemes were designed about SMA-13 asphalt mixture. They were basalt aggregate SMA, limestone aggregate SMA, basalt and limestone aggregate SMA. Through the study of low temperature and high temperature test of three kinds of combination, the low temperature performance of basalt and limestone aggregate SMA was better than that of the basalt aggregate SMA; and the high temperature performance was in between, thus providing important experimental data for the limestones replacing basalt in SMA pavement.

Abstract: A novel binuclear ruthenium vinyl complexes with dithienylethene unit II [RuCl (CO)(PMe₃)₃]₂(μ-CH=CH-DTE-CH=CH) has been synthesized and characterized by elemental analysis and NMR spectra. Meanwhile, the crystal of II was obtained and determined by X-ray single-crystal diffraction.

Abstract: The theoretical method of predicating second and third order elastic constants of cubic and tetragonal material are presented by using first-principles total-energy method combined with the means of homogeneous deformation. The predicted results of SrTiO₃ provide reasonable agreement with the reported experimental data, other theoretical results and Cauchy relations. Since high order elastic constants are very difficult to be measured, the methods presented here provide a valuable guidance for experiments and the investigation of high order elastic properties for cubic and tetragonal materials.

Abstract: The pseudo-potential plane wave (PP-PW) mehod with the generalized gradient approximation (GGA) is applied to study the electronic and optical properties of BaTi_0.5Ni_0.5O₃. The energy band structure, density of states (DOS) are obtained. The optical properties including the dielectric function, reflectivity, absorption spectrum, extinction coefficient, energy-loss spectrum and refractive index are also calculated and analyzed in detail.

Abstract: In this work, bulk polyamide 6 (PA 6) polymer was dissolved in the mixed solvent of phenol and dichloroethane with a weight ratio of 3:2 as a diluted solution. PA6 films were prepared from the diluted solution with varied polymer concentration. The crystallization and melting behaviors of the PA 6 films were studied using a differential scanning calorimeter. Results show that the ability of crystallization of the PA 6 films was obviously lower than that of the bulk PA 6 polymer. The effect of mixed solvent on the crystallization behavior of the PA 6 films is obvious.

Abstract: Calcium carbonate (CaCO₃) is a filler widely used in plastics. In this study, the effects of CaCO₃ content and size on the thermal properties of acrylonitrile-butadiene-styrene (ABS)/CaCO₃ composites were determined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA results in nitrogen showed that the maximum weight loss rate of the composites gradually decreased with increasing CaCO₃ content. TGA results in a mixed gas containing oxygen showed that CaCO₃ addition facilitated the degradation of ABS, and ABS degradation was completed at relatively low temperatures. The effect of nano-CaCO₃ on the thermal stability of the composites was similar to that of microsized CaCO₃.

Abstract: Si/Ag/C composite was prepared by two-step reaction. The phase and surface morphology of samples was studied by XRD and SEM. The electrochemical performance of the composite was investigated by charge/discharge test. SEM images indicate that the particles dispersed uniform and structure of the materials is stable. Electrochemical test results show that the initial discharged and charge capacities of Si/Ag/C composite are 2016.9 mAh/g and 1275.0 mAh/g, respectively. A reversible capacity of Si/Ag/C composite after 50 cycles is 325.5 mAh/g retained.

Abstract: A new type of interpenetrating phase composites (IPC) was prepared by impregnating open-cell aluminum foam (AF) with polyoxymethylene (POM) through an injection molding process, and their mechanical properties has been investigated. It shows relatively high bending strength and impact strength with compared to the pure AF and POM. With the addition of 10wt% polytetrafluoroethylene (PTFE) to POM, the mechanical properties of the IPC are further improved . On the other hand, Tribological tests of IPC were carried out with a pin-disk machine, and their worn surfaces were characterized by scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) to explore the wear mechanism. Results show that the friction coefficient of AF/POM/PTFE IPC is about 12.7% lower than that of AF/POM IPC and the wear loss reduced by 33.3%. The reason of the increase in the wear resistance can be explained by the transfer film which delays the wear process.