The states of vanadium species in V-SBA-15 synthesized under different pH values

V-SBA-15 (n_Si/V ≈ 10) mesoporous molecular sieves have been synthesized in different pH-value medias and characterized by XRD, N₂ adsorption, TEM, UV–vis, Raman, FT-IR, ESR, and NH₃-absorbed in situ FT-IR techniques. Results indicated that the pH value played an important role on the states of vanadium species in the prepared materials. As the pH value increased, the amount of the crystalline vanadium oxides decreased, the incorporated vanadium species with isolated tetrahedral (V⁵⁺) and square pyramidal coordination (VO²⁺) increased accordingly. At pH = 3.0, vanadium species were mainly in the silica framework and formed stronger acid sites, it seems to suggest that the linear configuration V⁵⁺–ONH₃H⁺–O–V⁴⁺ groups have been formed after ammonia was adsorbed. However, for the samples synthesized at the low pH values, the crystalline vanadium oxides existed and the amount of the dispersed tetrahedral vanadium species decreased, which caused the weaker acid sites.     

Synthesis and Characterization of Dicyclopentadiene – cresol Epoxy Resin

Summary Starting from cresol, the synthesis of dicyclopentadiene (DCPD) – cresol epoxy resin was conducted. DCPD-containing phenol resin (DPR) was prepared via Friedel–Crafts alkylation, whereas DCPD-containing epoxy resin (DER) was prepared via epoxidation of DPR with epichlorohydrin. The chemical structure was characterized with FTIR and ¹HNMR. Cure behaviors and glass transition temperature (T_g) of the resulting polymers were studied by differential scanning calorimeter (DSC). The results clearly indicated that cured polymer with a mixture of DCPD-cresol epoxy resin and diglycidyl ether of bisphenol A (E51) had higher T_g comparing with E51.     

Saline solution absorbency and structure study of poly (AA-AM) water superabsorbent by inverse microemulsion polymerization

A series of novel copolymer superabsorbents based on acrylamide (AM), acrylic acid(AA) were prepared by inverse microemulsion copolymerization using ammonium persulfate (APS) as the initiator and N,N-methylenebisacrylamide (MBA) as the crosslinking agent and OP-10 and SDS as complex surfactants. The synthetic variables (amount of crosslinking agent and initiator, water/oil ratio, monomer/surfactant ratio and AA/ Am ratio) and their effects on the absorbencies of the synthesized superabsorbents were investigated. The experimental results of superabsorbent polymers (SAPs) showed the maximum saline solution absorbency of 130 g/g within 75 min, and the saline solution absorbency of 111 g/g within 30 min. FTIR indicated the structure of the acrylic acid and acrylamide copolymer. SEM indicated that the particles prepared with higher crosslinker content (0.03%) showed smaller pore sizes and less porous structures compared with those with less crosslinker content (0.01%) and the number of the micropores largely decreased with the water/oil ratio increasing from 8% to 14%.     

Influence of ZnO buffer layer thickness on the electrical and optical properties of indium zinc oxide thin films deposited on PET substrates

The influence of the ZnO buffer layer thickness on the electrical and optical properties of In₂O₃–10 wt.% ZnO and ZnO bilayers deposited on polyethylene terephthalate (PET) substrates by RF magnetron sputtering were investigated. The optimum ZnO buffer layer thickness was found to be 90 nm which gives the lowest electrical resistivity of the bilayer of IZO and ZnO deposited on the PET substrate. The surface roughness decreases and diffusion of moisture and gas is more efficiently restrained, which contributes to lower the resistivity of the bilayer as the ZnO buffer layer thickness is increased. On the other hand, the total resistivity of the bilayer increases as the ZnO buffer layer thickness is increased because the resistivity of ZnO is higher than that of IZO. Introduction of a ZnO buffer layer does not nearly affect the IZO/ZnO/PET sample.     

喷涂工艺制备石英网眼多孔陶瓷的研究

以天然石英为骨料、粘土和长石为基料,采用喷涂工艺制备石英网眼多孔陶瓷。通过显微镜对其显微结构的观察,多孔陶瓷整体结构和孔径厚度非常均匀,具有连续开孔三维网状骨架结构,几乎没有很细的孔径存在。对不同气孔率多孔陶瓷的力学性能研究表明多孔陶瓷的抗压强度随孔隙率的减小而增大。     

(1-x)BaTiO3-xBi0.5Na0.5TiO3陶瓷的微结构与介电性能研究

采用传统电子陶瓷制备工艺制备了（1-x）BaTiO3-xBi0．5Na0．5TiO3（x=O．2～0．6）陶瓷,研究了不同Bi0．5Na0．5TiO3（BNT）含量下陶瓷的微结构特征和介电性能。结果表明：在BNT为0.2～0.6mol时,陶瓷样品均具有单一的钙钛矿结构,陶瓷的晶粒形状和大小随BNT含量的增加发生变化,BNT含量增加时样品的晶粒趋于减小,样品结构更为致密。陶瓷样品都具有稳定的介电性能,较高的介电常数,较低的介电损耗、BT-BNT40的介电稳定性最好。居里温度随BNT含量的增加而升高、当BNT含量为0．6mol时,T=210℃。     

N,N-二羟乙基乙酰乙酰胺的合成及应用

二乙醇胺与乙酰乙酸甲酯反应合成了硼酸酯键合剂原料N,N-二羟乙基乙酰乙酰胺。通过均匀设计与SPSS软件处理实验数据,确定了N,N-二羟乙基乙酰乙酰胺收率与各反应因素的回归方程;最佳反应条件为:n(乙酰乙酸甲酯)/n(二乙醇胺)=1.3,催化剂w(ZnAc2.2H2O)=0.25%(以二乙醇胺的质量计,以下同),反应温度140℃,反应时间2.5 h,减压蒸除未反应原料得产物。在该条件下,N,N-二羟乙基乙酰乙酰胺收率达84.9%。以N,N-二羟乙基乙酰乙酰胺制备的硼酸酯键合剂BA-5-2在5 L高能丁羟四组元推进剂装药实验中的应用结果显示:推进剂常温、高温各项力学性能指标均高于发动机设计要求15%,高温黏附指数φ=1.037,其综合力学性能优于醇胺类键合剂LAB-303B、二乙醇胺硼酸酯键合剂BAG-5及海因三嗪类键合剂BA603。     

碳含量对Fe—Cr—Ni系不锈钢永磁性能的影响

某些Ｆｅ－Ｃｒ－Ｎｉ系奥氏体不锈钢在特定的状态下可呈现出一定的永磁特性。基于这一事实,本文研究了碳含量对其永磁性能的影响。发现,随着碳含量的增加,３种不同Ｎｉ、Ｃｒ含量合金的矫顽力Ｈｃ增加,而剩磁Ｂｒ下降,此外,还给出了Ｎｉ、Ｃｒ含量范围随碳含量而改变的关系。     

干砂对EPS模样垂直向下盲孔充填性的研究

研究了干砂对ＥＰＳ模样中垂直向下盲孔的充填性能,主要工艺因素,如管径、管口深度、干砂粒形、振动方向、振动维数、振动频率、振动加速度等对垂直向下盲孔充填高度的影响。初步探讨了干砂对垂直向下盲孔充填的机理。     

Solids concentration simulation of different size particles in a cyclone separator

To deepen our knowledge of the flow in cyclones, the solids concentrations of different size particles in a scroll cyclone separator were numerically simulated by using the Lagrange approach on the platform of commercial CFD software package, FLUENT 6.1. The numerical calculations visualize that there exists a spiral dust strand near the cyclone wall and a dust ring beneath the cyclone top plate. There are two regions in the radial solids concentration distribution, with which the solids concentration is low in the inner region (r/R(dimensionless radial position) ≤ 0.75) and increases greatly in the outer region (r/R > 0.75). Large particles generally have higher concentration in the wall region and small particles have higher concentration in inner vortex region. The axial distribution of the solids concentration in the inner vortex region (r/R ≤ 0.3) shows that serious fine particle re-entrainment exists within the height of 0.5 D (cyclone diameter) above the dust discharge port. We study the effect of solids particle on the gas flow field by two-way couple. The concepts of back-mixing rate, first escaping rate and second escaping rate are proposed for quantifying the local flow phenomena.