混合导电体型氧透膜材料的研究

研究了具有氧离子导电性和电子导电性的钴系钙钛矿型复合氧化物混合导电体材料中氧的选择性透过能力,考察了该体系中 A 位低价金属离子置换量、置换金属离子的种类及 B 位置换金属离子的种类对氧的透过率的影响.结果表明:改变钙钛矿型复合氧化物的组成,提高材料中氧空位浓度和氧离子导电率,有利于提高氧离子的扩散速度,即提高氧的透过率和降低氧透过的起始温度.将钙钛矿型复合氧化物混合导电体氧透膜与固体电解质氧透膜进行了比较,前者具有结构简单的优点,有希望成为一种新型高温氧分离膜介质材料.     

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目前天然气净化中广泛应用的工艺方法绝大多数和立足于不同类型的化学反应，而从发展角度看，对若干类型特殊的原料天然气还有必要开发新型的分离过程，以进一步改善装置投资，操作成本，净化度和环境保护等方面的指标。８０年代以来，物理分离过程应用于天然气净化的势头方兴未艾，尤其是在其它工业中应用颇多的膜分离、低温分馏和变压吸附三大技术，在天然气净化中的应用也发展甚快。     

Functionality distribution and crosslink density of hydroxyl-terminated polybutadiene

A novel approach is proposed for estimating the average molecular weight between crosslinks (M?_c) from the functionality distribution of hydroxyl-terminated polybutadiene ( HTPB ). The functionality distribution of four free-radically polymerised HTPB prepolymers of varying hydroxyl content and molecular weight was determined by a combination of preparative and analytical gel permeation chromatography. The gumstock properties of the samples cured with stoichiometric amounts of toluene diisocyanate were not correlatable with the relative amounts of difunctional chain extender and multifunctional crosslinker present, unlike the case of HTPB with similar hydroxyl content and molecular weight. However, the mechanical properties and sol content could be correlated with the average molecular weight between crosslink sites, M?_c, of the cured polymer. The M?_c values derived by our method compare well with those of classical methods, and the observed differences are attributed to segmental entanglement. These M?_c values give consistently good correlation with all the gumstock properties, confirming the validity of our approach and the soundness of the techniques developed for the determination of the functionality distribution of HTPB .     

A novel model equation for the permeation of hydrogen in mixture with carbon monoxide through Pd–Ag membranes

Hydrogen permeance decrease, owing to the covalent interaction of carbon monoxide with the Pd–Ag membrane surface, represents a considerable drawback, since this decreases the efficiency of the alloy membranes. This work proposes a novel Sieverts–Langmuir's model taking into account the mentioned adsorption. The proposed model equation, in order to take into account the fraction of the membrane surface not active for hydrogen permeation, introduces Langmuir's isotherm, which is the surface loading in the classical Sieverts’ permeation equation. The evaluation of the parameter and the Langmuir affinity constant involved in the proposed model was carried out using experimental data measured using a 60 μm thick Pd–Ag commercial membrane at 647 K (374 °C), up to a total pressure of 700 kPa. The presented model yields, in a parametric form, a quantitative assessment of hydrogen permeance decrease caused by the adsorption of gases on Pd–Ag membrane surfaces. Therefore, this novel Sieverts–Langmuir's equation models hydrogen permeation through Pd–Ag-based membranes in the presence of inhibitor gases such as CO. In addition, by ab initio evaluation of the and the Langmuir affinity constant, the proposed Sieverts–Langmuir's equation can identify a new membrane with better efficiency.     

Effect of organic vapour interaction on permeation rate through polymer films

The permeability coefficients (P) of linalool, citral ethyl butyrate, d-limonene and octanal permeating through LDPE and ionomer films were measured alone as individual and as a component of a mixture at a temperature of 23 °C and in saturated water vapour. Values of P for ionomer film were approximately two orders of magnitude below those for LDPE for the compounds tested. Both PET and PETG films were found to be much better barriers against the compounds tested than LDPE and ionomer films. In general, the permeability, diffusion and solubility coefficients (P. D, and S) values measured in mixture were substantially less than the values obtained individually. Permeability behaviour of these compounds at low concentrations in the mixture was similar to that of permanent gases. Reduction of solubility coefficients in mixture permeation was greater with the higher solubility coefficients. These results provide a better understanding of the mechanism of vapour diffusion through polymers.     

氚在305铝合金及其预生膜中渗透率的研究

文章叙述了氚在305铝合金及其预生膜中渗透率的测量方法,推导出计算氚在305铝合金及其预生膜中的渗透率的经验公式。实验结果表明氚在镀预生膜的铝中的渗透率低,在100-250℃铝表面镀层阻挡氚渗透效果极为明显,而且温度越高效果越显著。     

(Z)-9-tetradecen-1-OL formate

Concentrations in air of (Z)-9-tetradecen-1-ol formate (Z-9-tdf), a mating disruptant ofHeliothis moths, were measured intermittently over a 22-day period in a corn field. The chemical was emitted from laminated plastic (Hercon^®) dispensers arranged in a square grid with 10-m spacing. Measurements were made at three heights near the center of the treated plot and 1 m downwind from disruptant dispensers. Concurrent measurements were made of wind speed, air temperature, and temperature gradient.Z-9-tdf concentrations ranged from below detectable levels to 195 ng/m³ and were generally highest in the horizontal plane of the dispenser. As wind speed decreased near sunset, concentrations increased sharply, then decreased again near midnight. SinceHeliothis moths mate in the evening and early night, the concentration pattern was favorable for mating disruption. Strong temperature inversions within the crop canopy, which occurred daily before sunset, did not apparently affectZ-9-tdf concentrations. Concentrations decreased steadily on successive sampling days after application, and, by day 27, ranged from 0 to 30% of those on day 6. The data suggest that the corn plants and the soil may act as sinks for the chemical vapor at night.     

基于广义预测的双电机同步控制

为减小多电机运动过程中的同步误差,提出了基于广义预测控制的两轴同步控制算法,其基本思想是在二次性能指标中加入同步误差的影响,使得该性能指标对单轴的跟踪误差、控制增量以及两轴之间的同步误差同时进行有限时段内的在线滚动优化,所得到的控制规律包含了两轴之间的交叉耦合作用,克服了单个电机受到扰动时两轴不能精确同步的问题,且该算法对系统的建模精度要求较低,在线滚动优化对负载扰动、随机噪声有很好的抑制作用。Matlab仿真实验结果表明,该控制算法能获得良好的单轴跟踪精度、两轴同步精度以及抗干扰能力。     

膜法脱除硫酸根的原理及影响因素探讨

介绍了膜法脱硫酸根的工艺流程、原理、主要影响因素及控制要求。     

Maxwell-Stefan理论模拟NaA沸石膜分离一氯甲烷中微量水的渗透特性

通过热浸渍晶种法制备了高质量的NaA沸石膜,并将其应用于蒸汽渗透脱除一氯甲烷中的微量水. 实验结果表明,NaA膜对该体系显示了优异的分离性能,水对一氯甲烷的分离系数高达74831,产品中的水含量从0.2582%(w)降低到0.005%(w). 将基于Maxwell-Stenfan理论和Langmuir理想吸附理论推导的吸附-扩散模型用于模拟水渗透流速与渗透侧真空度和进料温度的关系,预测趋势与实验值吻合很好,且拟合得到的参数与文献报道较接近,表明水蒸汽在NaA沸石膜中的传递为表面扩散机制,水蒸汽的吸附对渗透速率的贡献很大. 水蒸汽的吸附热为-34.15 kJ/mol.