Key Engineering Materials Vols. 575-576

Abstract: Aluminum Borate Whisker/Aluminum Phosphates composites (ABW/AP) added Si₃N₄ were prepared with pressure sintering technique. The influence of Si₃N₄ on the mechanical properties and dielectric properties were investigated. After sintered at 1050°C for 1h, the results showed that the flexural strength of the composites with 5wt% Si₃N₄ addition reach 167.29MPa,the dielectric constant (ε) and loss tangent (tanδ) of the composites are 2.99 and 0.0089 at 10GHz. The testing results was discussed.

Abstract: Granite, due to the poor adhesiveness with asphalt, cannot be widely used as aggregate in asphalt pavement. In this study, nanoscaled calcium carbonate (CaCO3), was selected as modifier to modify asphalt. The adhesion of aggregate and asphalt was evaluated by Boiling test method and the Marshall Test and Immersion Marshall Test were conducted on asphalt concrete (AC-16) according to the Standard Test Methods of Bitumen and Bituminous Mixture for Highway Engineering (JTG E20-2011). The results showed that When the Doping content of CaCO3 (%) is 7%, the adhesion levels reached up to 5 grade and achieved the project requirements. The Immersion Marshall Stability (MS1) of AC-16 CaCO3 modified asphalt concrete can improve 27.6% than that the Matrix asphalt concrete.

Abstract: In this present work, a new method for preparing NiO doped SnO₂ nanoflowers by hydrothermal route is suggested. The composition and microstructure of samples were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and Fourier transform infrared spectrum (FTIR). Moreover, a possible formation mechanism was discussed.

Abstract: Uniform MoO₃ nanobelts were synthesized through a fast and simple hydrothermal route without any other agents. The hydrothermal reaction was performed at 180 °C for 12 h using a HNO₃ aqueous solution as the solvent. The phases and microstructures were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicated that the sample obtained was an orthorhombic MoO₃ phase, and had a belt-like morphology with lengths of 510 μm and apparent widths of about 220 nm. The MoO₃ nanobelts obtained were used as the sensing materials to fabricate chemical sensors for detection of some volatile organic compounds (VOCs) (including ethanol, methanol, isopropanol, acetone, methanal, and benzene). The gas-sensing results indicated that the sensor of the α-MoO₃ nanobelts has enhanced ethanol-sensing performance, e.g., with the highest sensitivity of S_r =144 for 500 ppm ethanol vapor operating at 300 °C.

Abstract: Unsaturated polyester was prepared with adipic acid (AA), fumaric acid (FA), itaconic acid (IA) and 1, 6-hexanediol (HD) by enzyme-catalyzed polmerization. The insoluble gel fraction (Q_s), as the cross-linking degree of cured unsaturated polyesters which could be self-cross-linked at high temperature through C=C in it, was got by Soxhlet Extraction. The properties were investigated by FT-IR, ¹H NMR, DSC, XRD and so on. The results indicated that the C=C in unsaturated diacids reduced the acitvity of N435, which affected the polmerization. With the introduction of C=C of IA or FA, the M_n of polyester reduced. The C=C could self-cross-link under high temperature for lengthy time. The higher the temperature and the longer the time, the Q_s increased. As the C=C of IA was in the side chain, it could move easily. Then Q_s of poly (AA-co-IA-co-HD) was higher than ploy (AA-co-FA-co-HD). With the increased content of unsaturated diacid, Q_s increased. And the biodegradation of cross-linked polyesters became worse.

Abstract: In this investigation, dodecyl dimethyl (vinylbenzyl) ammonium chloride is synthesized through the reaction between 4-vinylbenzyl chloride and N,N-dimethyl-dodecylamine. This resultant compound is characterized by H-NMR, FTIR, TGA, and antibacterial assays. It is found that this chemical reaction is achievable. Moreover, it is also observed that this compound have good thermal ability, and its decomposition temperature is 207°C. The antibacterial tests prove that it have excellent antibacterial abilities against E.coli and S. aureus. Therefore, these results are demonstrated that it can be applied in bulk modification of polymers for better antibacterial and mechanical properties.

Abstract: Hyperbranched polymer/HTPB-PU IPNs were prepared, when HTPB (hydroxyl-terminated polybutadiene) and IPDI (isophorone diisocyanate) were cured into polyurethane (HTPB-PU) at the existence of hyperbranched polymer. Differential scanning calorimetry (DSC) was adopted to study the influence of hyperbranched polymer on thermal properties of HTPB-PU, while IPNs were formed. The result shows that the existance of hyperbranched polymer makes glass transition temperature of HTPB-PU reduces by around 2°C and that HTPB-PU lowers the melting point of hyperbranched polymer. Hyperbranched polymer plays a role of internal plasticization on HTPB-PU, and HTPB-PU influences crystallization of hyperbranched polymer in return.

Abstract: The kinetics of the thermal cure and ceramization of preceramic prehydropolysilazane (PHPS) was investigated by thermogravimetric analysis (TGA) under nitrogen atmosphere. The results indicated that the gases captured during the thermal cure and ceramization process of PHPS, which had three main weight loss events. The corresponding kinetic parameters including activation energy, pre-exponential factor and empirical order of the thermal cure and ceramization stages were evaluated by using Ozawa and Kissinger metnods, respectively.

Abstract: Poly [cyclotriphosphazene-co-(4, 4-sulfonyldiphenol)] microspheres grafted by water-soluble chitosan (PZSMS-g-Cs) were successfully prepared via a facile strategy. The water-soluble chitosan, which has low polymerization degree and narrow molecular weight distribution, was prepared by degradation from common macromolecular chitosan. The morphology and structure of PZSMS-g-Cs were characterized by SEM and TEM. The successful fabrication of PZSMS-g-Cs was confirmed by FTIR. The product PZSMS-g-Cs was found to have good water soluble property. The paper presents a simple, economic and efficient route to preparing functional hybrid inorganic-organic microspheres with good water soluble property.

Abstract: The influence of the BaSiO₃ dopant on the dielectric properties of (Ba,Sr)TiO₃(BST) capacitor ceramics was studied using conventional capacitor ceramics solid state method and XRD , SEM and other analytical methods. The results show that BaSiO₃ doping can improve the sintering and microstructure of the capacitor ceramics. SEM study show that BaSiO₃ doping can make grain grow uniformly and suppress the grain to grow up, and the structure of ceramics is compact with little pore. XRD study show that there is little SiO₂ phase and little influence of BST lattice parameter when BaSiO₃ doped amount is 3 mol%.The dielectric properties of BST ceramics doped with 3 mol% BaSiO₃ are as follows: dielectric constant (ε_r) of 1792, which is a little higher than undoped BST ceramics, tanδ of 1%, which is decreased 7.24% compared with undoped BST ceramics, and the sintering temperature decreases 40°C.