连续高速分散混合器内的流体力学性能-II. 数值模拟

采用计算流体力学(CFD)方法研究连续高速分散混合器(CRS)的流体力学特性. 采用FLUENT 6.2软件，选用标准k-e模型和滑移网格(SM)法，对CRS进行三维流动场的数值模拟. 功率消耗的预测值与实验结果吻合良好，随雷诺数的增大功率准数NP基本不变，其模拟值为5.99，与实验的误差为13.7%. 在中小流量下，水力学性能的模拟值与实验值吻合较好，但较高流量下由于液沫夹带而无法准确预测. 模拟结果表明，CRS的最大泵送效率仅为13%，其功率消耗主要用于物料高效剪切混合；混合腔内的宏观流动场、剪切速率及湍流耗散率均呈非对称分布；对应转子不同的几何位置，定子槽内产生流型不同的漩涡，模拟结果与文献数据相吻合. 研究结果可为工业CRS的优化设计提供参考.     

高频脉冲电场作用下乳状液液滴动力学模型

基于乳状液中液滴在电场中的受力情况的分析，建立了W/O乳状液中液滴振荡固有频率公式，从理论角度分析和解释了高频脉冲电场对W/O乳状液的破乳机理，从力学的角度分析了最佳频率存在的理论基础，并推导出了最佳频率的计算公式。该固有频率与液滴尺寸、界面张力、黏度、温度、密度等有关。为了验证最佳频率公式的可靠性，用正辛烷乳状液进行了室内实验。实验结果表明，理论最佳频率公式的预测结果与实验测得的最佳频率结果吻合，经修正后与白油实验结果也非常接近。     

Studies on crystal morphology and crystallization kinetics of polypropylene filled with CaCO3 of different size and size distribution

Changes in the crystal morphology, crystallinity, and the melting temperature of thermoplastics resulted in significant changes in the mechanical behavior of composites containing them. For this reason, the research of crystal morphology and crystallization kinetics in thermoplastic composites became an important requirement. The thermoplastic filled with the filler of different size gradation was a new method for improving processability of thermoplastic composites. We have previously reported that the melt viscosity of polypropylene (PP) composites, which were filled with 30 wt % CaCO₃ of effective size gradation, could be evidently declined. In this study, two sizes of CaCO₃, 325 meshes and 1500 meshes, were blended by different proportions and filled into PP matrix with 30 wt %. Crystal morphology and isothermal crystallization kinetics of a series of composites were characterized by differential scanning calorimeter (DSC) and polarizing microscope. The results showed that composites filled with CaCO₃ of effective size gradation leaded to a well‐crystalline order and a large crystal size, while their isothermal crystallization kinetics and crystallization rate constant (k) were declined, and their Avrami exponents (n) and crystallization half‐life (t_1/2) were increased compared with the composites filled with single size CaCO₃. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2437–2444, 2006     

膨胀型阻燃剂对聚丙烯-木粉复合材料阻燃及性能的影响

主要以聚磷酸铵(APP)、季戊四醇(PER)、以及自制的成炭发泡剂(CFA)复配成的膨胀型阻燃剂对聚丙烯-木粉复合材料进行阻燃.并通过一系列的性能实验研究了不同的阻燃剂配方及阻燃剂含量对聚丙烯-木粉复合材料的力学性能、阻燃性能、流变行为以及热降解行为的影响.结果表明,膨胀型阻燃体系可以提高聚丙烯-木粉复合材料的LOI与成炭性,当添加量为25%时,APP与PER复配阻燃的复合材料的LOI可达27.5,800℃时残余炭含量为19.24%.而且该阻燃剂的加入对提高材料的拉伸和弯曲强度有一定作用.     

Preparation and characterization of sulfonated polyetherimide/polyetherimide blend membranes

Polyetherimide (PEI) was sulfonated by chlorosulfonic acid (CSA) in 1,2‐dichloroethane for the first time. With the increase of the CSA/PEI repeat unit ratio and/or reaction time, the ion‐exchange capacity (IEC) of the sulfonated polyetherimide (SPEI) increased accordingly. Water‐uptake testing and contact‐angle measurement showed that the hydrophilicity of the SPEI increases with the increase of the IEC. Membranes were fabricated from SPEI/PEI blends with different ratios. The morphologies of the blend membranes were examined by scanning electron microscopy, which showed that the membrane pore size is larger when SPEI with higher IEC was used. With the increase of SPEI ratio in the blend membranes, the membrane pore size also increased. The contact‐angle data of the membranes showed that the hydrophilicity of the blend membrane was elevated because of the sulfonate group on the SPEI molecular backbone. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1709–1715, 2004     

N-TiO2/Ti3C2复合材料的原位合成及其光催化性能

以钛碳化铝、氢氟酸、氟硼酸钠为原料，以尿素为氮源，通过简单的溶剂热反应，在高导电性的Ti3C2 MXenes（二维过渡金属碳化物）纳米片上原位生长氮元素掺杂的TiO2纳米片，合成了二维N-TiO2/Ti3C2光催化复合材料。采用X射线衍射仪、扫描电子显微镜、透射电子显微镜、X射线光电子能谱仪、紫外-可见漫反射光谱仪、光致发光光谱仪等对催化剂样品进行了结构表征。结果表明，在可见光照射下，N-TiO2/Ti3C2复合材料对罗丹明B（RhB）表现出较好的光催化降解性能，其降解速率是纯TiO2的8.41倍，在150min内，罗丹明B降解率达到96.3%。这主要是由于氮元素的掺杂缩小了TiO2的带隙，将光响应范围扩展到可见光区域。同时，TiO2纳米片的原位生长使其与具有优异电导率的Ti3C2 MXenes纳米片形成了紧密的接触界面，促进了光生载流子的分离和迁移。自由基捕获实验和电子自旋共振测试结果显示，•O2-和•OH是N-TiO2/Ti3C2光催化体系降解罗丹明B的主要活性物种。此外，N-TiO2/Ti3C2复合材料具有良好的稳定性和可重复利用性。     

Low temperature solid-state synthesis routine and mechanism for Li3V2(PO4)3 using LiF as lithium precursor

Monoclinic lithium vanadium phosphate, Li₃V₂(PO₄)₃, has been successfully synthesized using LiF as lithium source. The one-step reaction with stoichiometric composition and relative lower sintering temperature (700 °C) has been used in our experimental processes. The solid-state reaction mechanism using LiF as lithium precursor has been studied by X-ray diffraction and Fourier transform infrared spectra. The Rietveld refinement results show that in our product sintered at 700 °C no impurity phases of VPO₄, Li₅V(PO₄)₂F₂, or LiVPO₄F can be detected. The solid-state reaction using Li₂CO₃ as Li-precursor has also been carried out for comparison. X-ray diffraction patterns indicate that impurities as Li₃PO₄ can be found in the product using Li₂CO₃ as Li-precursor unless the sintering temperatures are higher than 850 °C. An abrupt particle growth (about 2 μm) has also been observed by scanning electron microscope for the samples sintered at higher temperatures, which can result in a poor cycle performance. The product obtained using LiF as Li-precursor with the uniform flake-like particles and smaller particle size (about 300 nm) exhibits the better performance. At the 50th cycle, the reversible specific capacities for Li₃V₂(PO₄)₃ measured between 3 and 4.8 V at 1C rate are found to approach 147.1 mAh/g (93.8% of initial capacity). The specific capacity of 123.6 mAh/g can even be hold between 3 and 4.8 V at 5C rate.     

端氨基聚脲聚氨酯环氧树脂体系的固化反应及粘接性能

本文采用DTA和FT-IR研究了端氨基聚脲聚氨酯固化环氧树脂的反应特性,考察了被粘表面状态、偶联剂和促进剂、填料等对剪切强度性能的影响。并对该粘合剂耐化学腐蚀性进行了试验,说明具有好的耐腐蚀性。     

Fe doping effect on EuTiO3: The magnetic properties and giant magnetocaloric effect

The magnetic properties and magnetocaloric effect for EuTi_1-xFe_xO₃ (x = 0.05, 0.1) compounds are investigated. When a part of Ti⁴⁺ions were substituted by Fe ions, the AFM ordering can be significantly changed to be FM. The EuTi_1-xFe_xO₃ (x = 0.05, 0.1) compounds exhibit a PM to FM transition with decreasing temperature and the Curie temperature is 6 K. Under the field changes of 1 T, and RC are valued to be 10.1 J/kg K and 50.2 J/kg for EuTi_0.95Fe_0.05O₃; 9.6 J/kg K and 47.7 J/kg for EuTi_0.9Fe_0.1O₃, without magnetic and thermal hysteresis. RC is almost twice as much as EuTiO₃ (27 J/kg) as substitution of Fe³⁺ ions for Ti⁴⁺ions, which may be attributed to the magnetic transition (AFM to FM). Therefore, the giant and large RC suggest the EuTi_1-xFe_xO₃ compounds are good materials for magnetic refrigerant.     

HB－901水处理剂研究及应用

针对优质高效水处理剂短缺的问题，研制出一种新型水处理剂ＨＢ－９０１。以丙烯酸和丙烯酸酯为原料，采用溶液聚合法制得产品，产品质量符合Ｑ／ＨＦＦ０２．０３－９１标准要求，在工业循环水系统得到了广泛的应用，效果良好。