Effect of polystyrenes with different architectures on the β‐nucleating efficiency and toughening of isotactic polypropylene

The effect of polystyrenes (PSs) with different architectures (three‐arm star‐shaped polystyrene (sPS), comb‐like branched polystyrene (cPS) and linear polystyrene) on their β‐nucleating efficiency for isotactic polypropylene (iPP) during crystallization and final impact and the tensile properties of iPP/PS blends were investigated by dynamic rheological measurements, SEM, DSC, polarized optical microscopy, wide angle X‐ray diffraction and mechanical property measurements. The results show that the architecture of PS has marked influence on its dispersibility in iPP and β‐nucleating efficiency. For iPP/cPS blend, plenty of short side chains reduce the probability of cPS chain entanglements, facilitating the interdiffusion between iPP and cPS chains. A favorable interfacial interaction results in good dispersibility, high β nucleating efficiency and an excellent toughening effect of cPS on iPP. However, the relatively high chain entanglement degree of sPS may not be in favor of chain diffusion between iPP and sPS and therefore relatively poor dispersibility and toughening effect are obtained. The elongation at break and impact strength of iPP were dramatically improved, especially with the addition of 1 wt% cPS. The toughening mechanism of PS on iPP is the dissipated energy caused by cavitation and the β‐nucleating effect of PS. © 2018 Society of Chemical Industry     

超声空化合成安息香

采用超声空化、相转移催化法,用水/乙醇为反应介质,以苯甲醛为原料,盐酸硫胺（VB1）为催化剂,在碱性溶液中反应制得安息香。对原料配比、反应温度、反应时间、体系pH值、相转移催化剂的种类等各种反应条件的影响作了详细的研究。实验得到最优条件为：乙醇/水二元混合溶液中,苯甲醛5 mL,盐酸硫胺2.0 g,相转移催化剂用量占苯甲醛质量的百分比为10%~12%,蒸馏水量2 mL,乙醇量8 mL,体系的pH值控制在9.3~9.7之间,水浴超声空化控温在70℃左右,反应时间90 min,超声功率80%。最优条件下收率达到93.57%,产品含量在90%以上。该工艺具有反应条件温和、转化率较高等优点。     

水力空化作用强化椰油酰化大豆粕蛋白工艺的研究

以大豆粕为研究对象,通过水力空化作用强化椰油酰氯酰化大豆粕蛋白工艺。在自行设计的水力空化强化反应设备上,研究了水力空化的压力、时间、温度和料液比(水溶性大豆粕蛋白溶液与椰油酰氯的体积比)等因素对酰化产率的影响,以单因素试验为基础,利用响应面法优化了工艺条件,并对酰化产物的表面性能进行了测定。结果表明水力空化作用强化椰油酰化大豆粕蛋白的较优工艺条件为:压力0.29 MPa、时间49 min、温度52℃、液料比1.8。在此条件下,酰化产率达到98.1%,酰化产物表面性能良好。     

High-rate calcium removal using the Hyperkinetic Vortex Crystallization (HVC) process for reuse of electronics wastewater

The Hyperkinetic Vortex Crystallization (HVC) process using hydrodynamic cavitation technology was investigated to remove high calcium levels from the effluent of the fluoride removal process used in a semiconductor manufacturing company. Due to low alkalinity in the effluent of this wastewater, addition of sodium carbonate was necessary. The relatively stable effluent calcium concentration of 8.0-52.8 mg/L was achieved although the influent calcium concentration severely fluctuated in the range of 173-371 mg/L. A calcium removal efficiency of 84.5-97.0% was determined with the HVC process. To confirm the cavitation effect, the calcium removal process was operated with and without the use of the VRTX cavitation system. The calcium removal efficiency increased from 63.5% to 91.7% when the VRTX unit was operating. The change of the calcite shape from plate to a spherical form by VRTX application was also observed. This can enhance calcium removal because of the larger specific surface area for adsorption of newly produced colloidal calcites. The conversion of the calcite shape to spherical would also prevent (limit) formation of calcite scale in the inner wall of pipes and reactors.     

铁铬合金空蚀过程中电化学力学性能相关性

研究了4种铁铬合金在氯化钠溶液体系中的空泡腐蚀行为. 重点考察了合金性能及空泡作用区相对大小对合金空蚀损失量的影响. 结果表明 合金空蚀损失量随空泡作用区与非空泡作用区表面面积比的增大而增加; 合金的耐蚀性能和力学性能共同影响其空蚀损失量.     

水轮机转轮抗气蚀堆焊工艺及效益分析

通过采用堆焊技术对轴流式水轮机转轮气蚀进行处理,并不断地进行论证、总结、提高,收到了良好的效果,提高了机组的出力,延长了转轮使用寿命,创造了较好的经济效益.     

Roles of Pumps and Bypass in Chemistry Induced by Hydrodynamic Cavitation

In this investigation, a self‐made low pressure device (up to 100 psi) for creating hydrodynamic cavitation was optimized by using the Weissler reaction. Optimal upstream pressure for the reaction was obtained for a single line system (without bypass) as 29 psi. The effects of the centrifugal pump and the bypass were significant as compared with the effect of the restrictions investigated. Therefore, the use of more lines is proposed. The effects of different restrictions (valve, one‐hole plate, and multi‐hole plate) were investigated and multi‐hole plates show better efficiency.     

有效防止离心泵的“汽蚀”危害的方案

针对离心泵应用中的汽蚀问题,提出解决方案,并介绍如何增强离心泵的抗汽蚀性能.     

Cavitation and grain boundary sliding during creep of Mg-Y-Nd-Zn-Mn alloy

Creep of squeeze-cast Mg-3Y-2Nd-1Zn-1Mn alloy was investigated at the constant load in the stress range of 30-80 MPa. Tensile creep tests were performed at 300℃up to the final fracture.Several tests at 50 MPa were interrupted after reaching the steady state creep;and another set of creep tests was interrupted after the onset of ternary creep.Fraction of cavitated dendritic boundaries was evaluated using optical microscopy.Measurement of grain boundary sliding by observation of the offset of marker lines ...     

The Use of Ensemble Averaging to Increase the Sensitivity of Measurements with Flame Photometers†

SUMMARY

A number of steps that optimize the signal-to-noise ratio, S/N, were provided in the flame spectrophotometer design, including beam chopping followed by narrow-band-tuned amplification. It has been shown that the relative effectiveness of three methods of optimizing or enhancing S/N to increase the sensitivity and decrease the lower limit of detection of flame photometric measurements increases in this order: linear detection followed by RC filter averaging; linear detection followed by RC filter averaging followed by active integration averaging; ensemble averaging of output of tuned amplifiers. Correlation in both the frequency and time domains is provided, respectively, by tuned amplification and by ensemble averaging. Other advantages of the use of ensemble averagers in flame photometry are pointed out, including correction for background, calibration in the sample matrix, data transformations, faster wavelength scanning without S distortion, testing of design steps to optimize S/N, digital data acquisition, and the attainment of a greater advantage from the dependence of multiplier phototube gain upon the spectral sensitivity of the photocathode and upon the voltage applied to the tube. To obtain measurements of highest sensitivity, all portions of the measurement system must be designed to optimize S/N wherever economically and technically feasible in order to obtain a system output that has the highest S/N. The enhancement of the optimized S/N by ensemble averaging can provide a further increase in the sensitivity of measurement, or, in a practical problem, enhancement of S/N by ensemble averaging may be attractive because of the achievement of sufficiently high sensitivity (and low detection limits) with the use of relatively simple procedural steps.