Effect of MgO–TiO2–SiO2 additions on in-situ anisotropic grains growth and mechanical properties of corundum abrasive using pseudo-boehmite as raw material

Microcrystalline corundum abrasives with a duplex microstructure consisting of elongated anisotropic grains and fine equiaxed grains were fabricated via sol-gel processes using pseudo-boehmite as raw material. Elongated anisotropic grain, as a second phase reinforcement, significantly improved the fracture toughness and strength of samples. When the sample was doped 2 wt% MgO–TiO₂–SiO₂ additions with the molar ratio of 3:5:11, elongated anisotropic grains had the highest aspect ratio and were uniformly distributed among the fine equiaxed grains matrix. In addition, the sample obtained a maximum density above 3.92 g cm⁻³, single particle compressive strength of 56.4 N and fracture toughness of 5.93 MPa m^1/2. The relationship between the microstructure and the mechanical properties of the abrasives was also discussed in detail. Moreover, toughening mechanism of elongated anisotropic grains was clearly explained by charactering crack propagation and fracture surfaces of samples.     

Novel brominated compounds using in binary additives based organic solar cells to achieve high efficiency over 10.3%

Solvent additives have been considered as a simple and efficient method to increase the performance of bulk-heterojunction (BHJ) organic solar cells, in which, the morphology of the active layer could obtain further improvements by using the binary solvent additives. In this paper, a series of brominated compounds, 1-Bromo-4-butylbenzene (Brbb), 1-Bromo-4-n-hexylbenzene (Brbh) and 1-Bromo-4-n-octylbenzene (Brbo), have been respectively incorporated with 1, 8-diiodooctane (DIO) and regarded as binary solvent additives to fabricate highly efficient bulk heterojunction (BHJ) organic solar cells (OSCs). Compared with the BHJ film based on single additive, the binary additives contained BHJ film shows increased optical absorption, efficient charge transport and better active layer morphology, leading to an enhancement of short-circuit current (J_SC) together with a higher achieved fill factor (FF). The conventional BHJ device using PTB7: PC₇₁BM or PTB7-th: PC₇₁BM with the binary solvent additives exhibit enhanced PCE of 8.13% and 10.31%, respectively, which is much higher than that of single additive based devices (7.04% for PTB7 and 8.73% for PTB7-th). The optimized performance of BHJ devices indicates that these brominated compounds are promising additives to improve device efficiency.     

Thickness dependent growth and ferroelectric/dielectric properties of phase-pure 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 thin film derived from a modified sol-gel process

Annealing parameter and thickness are two significant factors affecting microstructure and electrical performance of sol-gel derived 0.65Pb(Mg_1/3Nb_2/3)O₃?0.35PbTiO₃ (0.65PMN-0.35PT) thin film. In this paper, various durations are firstly selected for the investigations on annealing parameter of 0.65PMN-0.35PT thin film. Enhanced insulating and ferroelectric properties can be obtained for the film annealed for 1 min due to its phase-pure and homogeneous perovskite structure. Based on this, a series of 0.65PMN-0.35PT thin films with various thicknesses by modifying deposition layer are synthesized annealed for 1 min and the effects of thickness on crystalline, insulating, ferroelectric and dielectric properties are characterized. It reveals that thickness-dependent behavior can be noticed for 0.65PMN-0.35PT thin film with the results that the 8-layered film possesses a relative large remanent polarization (P_r) of 23.34 μC/cm², and reduced leakage current density of 10^?9 A/cm² with low dissipation factor (tanδ) of 0.03 can be achieved for the 14-layered film.     

流化床型络合液再生工艺研究

随着工业化进程的加快,如何减少氮氧化物的排放受到了人们的强烈关注。目前,由于络合吸收法对一氧化氮(NO)具有良好的吸收性能,被视为未来脱硝技术的重要发展方向,但络合液的再生仍然是一个难题。本文针对络合脱硝中Fe(II)EDTA-NO络合液再生困难且无法连续运行问题进行了探究。以氮掺杂多孔碳为载体,钯纳米微团为活性组分制备出颗粒状Pd/NPCs催化剂,通过X射线衍射、透射电子显微镜、X射线光电子能谱对Pd/NPCs进行表征。结果表明,钯纳米微团成功负载到载体上,其平均粒径为2.36 nm,Pd⁰含量为68%(质量分数),对还原Fe(II)EDTA-NO有着良好的催化活性。进一步探究了溶液pH、反应温度、氧含量及液气比等因素对催化剂催化还原Fe(II)EDTA-NO的影响,搭建了一套可持续运转的流化床试验装置,其评价试验结果表明在气流量为200 L/h,NO含量为0.07%(体积分数)条件下,可以维持脱硝率80%以上3 h。     

Grafting of epoxy chains onto graphene oxide for epoxy composites with improved mechanical and thermal properties

Epoxy composites filled with both graphene oxide (GO) and diglycidyl ether of bisphenol-A functionalized GO (DGEBA–f–GO) sheets were prepared at different filler loading levels. The correlations between surface modification, morphology, dispersion/exfoliation and interfacial interaction of sheets and the corresponding mechanical and thermal properties of the composites were systematically investigated. The surface functionalization of DGEBA layer was found to effectively improve the compatibility and dispersion of GO sheets in epoxy matrix. The tensile test indicated that the DGEBA–f–GO/epoxy composites showed higher tensile modulus and strength than either the neat epoxy or the GO/epoxy composites. For epoxy composite with 0.25 wt% DGEBA–f–GO, the tensile modulus and strength increased from 3.15 ± 0.11 to 3.56 ± 0.08 GPa (∼13%) and 52.98 ± 5.82 to 92.94 ± 5.03 MPa (∼75%), respectively, compared to the neat epoxy resin. Furthermore, enhanced quasi-static fracture toughness (K_IC) was measured in case of the surface functionalization. The GO and DGEBA–f–GO at 0.25 wt% loading produced ∼26% and ∼41% improvements in K_IC values of epoxy composites, respectively. Fracture surface analysis revealed improved interfacial interaction between DGEBA–f–GO and matrix. Moreover, increased glass transition temperature and thermal stability of the DGEBA–f–GO/epoxy composites were also observed in the dynamic mechanical properties and thermo-gravimetric analysis compared to those of the GO/epoxy composites.     

Direct determination of transference numbers of LiClO4 solutions in propylene carbonate and acetonitrile

Transference number measurements were determined by a direct method for LiClO₄ solutions in propylene carbonate and acetonitrile at 25 °C. A comparison is reported between theoretical calculations of transference numbers using a model based on the Lee–Wheaton theory with values of conductometric parameters, and thermodynamic ion pairing constants determined from previously reported conductivity data.     

Development of ruthenium-based bimetallic electrocatalysts for oxygen reduction reaction

Ruthenium-based bimetallic electrocatalysts with non-noble metals such as Ti, Cr, Fe, Co and Pb were synthesized on a porous carbon support using a chelation process. Rotating ring disk electrode measurements indicated that RuFeN_x/C showed the catalytic activity and selectivity toward the four-electron reduction of oxygen to water comparable to those of the conventional Pt/C catalysts. The performance of the membrane-electrode assembly prepared with the RuFeN_x/C cathode catalyst was evaluated for 150 h of continuous operation.     

Polyaniline with ω-hydroxyalkoxy pendant substituent on the meta-position

A series of meta-substituted polyaniline derivatives, poly[3-(ω-hydroxyhexoxy)aniline], poly[3-(ω-hydroxyoctoxy)aniline], poly[3-(ω-hydroxydecoxy)aniline] and poly[3-(ω-hydroxydodecoxy)aniline] have been synthesized via chemical oxidative polymerization. The resulting polymers show enhanced solubility in organic solvent. The polymerization yield is increased and the reaction is accelerated by the addition of aniline. The homopolymers can attain conductivity in the range of 10⁻⁶ to 10⁻⁴ S cm⁻¹ after protonic doping with HCl. Upon doping oxidatively with iodine, the conductivity is ca. 10⁻⁵ to 10⁻³ S cm⁻¹. For the copolymers with aniline (15 mol%), the corresponding conductivity is higher, 10⁻⁵ to 10⁻³ S cm⁻¹ upon HCl doping and 10⁻⁴ to 10⁻² S cm⁻¹ upon iodine doping. Thermogravimetry (TG) of the polymer depicts two major weight loss steps corresponding to the degradation of side chain and the thermal breakdown of the backbone, respectively. The polymers are largely amorphous but show an increase in crystallinity with increasing pendant chain length. The polymers were also subjected to FT-IR, UV–VIS and X-ray photoelectron spectroscopy (XPS) studies.     

Synthesis and characterization of polyaniline–maleic acid salt

Polyaniline–maleic acid (PANI–MAc) salts have been prepared at various maleic acid concentrations. The salts are characterized by using infrared (IR), UV/VIS Spectroscopy, thermogravimetric analysis and conductivity measurements. Blends of PANI–MAc were made with styrene–butyl acrylate (ST–BuA) copolymer and percolation threshold determined.