Transient electrophoresis of a charged porous particle

The starting electrophoretic motion of a porous, uniformly charged, spherical particle, which models a solvent-permeable and ion-penetrable polyelectrolyte coil or floc of nanoparticles, in an arbitrary electrolyte solution due to the sudden application of an electric field is studied for the first time. The unsteady Stokes/Brinkman equations with the electric force term governing the fluid velocity fields are solved by means of the Laplace transform. An analytical formula for the electrophoretic mobility of the porous sphere is obtained as a function of the dimensionless parameters , , , and , where a is the radius of the particle, κ is the Debye screening parameter, λ is the reciprocal of the square root of the fluid permeability in the particle, ρ_p and ρ are the mass densities of the particle and fluid, respectively, ν is the kinematic viscosity of the fluid, and t is the time. The electrophoretic mobility normalized by its steady-state value increases monotonically with increases in and , but decreases monotonically with an increase in , keeping the other parameters unchanged. In general, a porous particle with a high fluid permeability trails behind an identical porous particle with a lower permeability and a corresponding hard particle in the growth of the normalized electrophoretic mobility The normalized electrophoretic acceleration of the porous sphere decreases monotonically with an increase in the time and increases with an increase in from zero at .     

磺化酚酞型聚醚砜膜的制备及其阻醇和质子导电性能

直接甲醇燃料电池 (Directmethanolfuelcell,DMFC)以高效、清洁和燃料储运方便等优点适宜于作为各种用途的可移动动力源 ,成为 2 0世纪 90年代以来研究与开发的热点[1,2 ] .目前 ,这种电池的研究难点主要集中在催化剂不稳定和质子交换膜透醇上 .一张好的DMFC膜不但要可传递质子、绝缘电子 ,还应具有良好的阻醇性能 .如果膜的阻醇性能不好 ,甲醇会穿过膜到达阴极 ,与氧直接反应而不产生电流 ,不但造成燃料的浪费 ,同时也影响阴极的正常反应 ,使电池效率下降[3 ] .目前广泛应用于燃料电池中的Nafion 系列膜是由美国DuPont公司生产的一种…     

EFFECT OF CHEMICAL STRUCTURE OF SULFOXIDE GRAFTED POLY (VINYL ALCOHOL) ON GAS PERMEABILITY

The effects of chemical structure, i. e. side chain structure and their contents, on thepermeability of pure SO_2, N_2 and their mixture gases for the sulfoxide grafted poly (vinylalcohol) (RVSO-PVA) membranes have been investigated:where R=Me, Et, Pr, t-Bu and Ph. It was notable that introduction of sulfoxide group intoPVA side chain greatly enhanced the permselectivity of sulfur dioxide. SO_2 permeability andseparation factor of these polymers increased markedly as the size of side chain increased. Thesulfoxide content of the polymer also played an important role in the pure and mixture gasespermeation. Some explanations have been made to interpret this unique gas separation behaviour.     

Sulfonated poly(ether ether ketone)/polyaniline composite proton-exchange membrane

Sulfonated poly(ether ether ketone) (PEEK) was prepared by sulfonation of commercial Victrex^@ PEEK and degree of sulfonation was found to be about 44.5% by ¹H NMR. Sulfonated PEEK/polyaniline composite membranes, in order to prevent methanol crossover, were prepared by chemical polymerization of a thin layer of polyaniline (PANI) in the presence of a high oxidant concentration on a single face modification. FTIR and PANI coating density studies confirmed the loading of PANI in sulfonated PEEK membrane matrix. PANI composite membranes with different polymerization time were prepared and subjected to thermogravimetric analysis as well as electrochemical and methanol permeability study to compare with sulfonated PEEK and Nafion 117 membrane. Ion-exchange capacity, water uptake, proton transport numbers and proton conductivities for different PANI composite sulfonated PEEK (SPEEK) membranes were found to be dependent on the coating density of the PANI in the membrane matrix and were slightly lower than that of Nafion 117 membrane. Methanol permeability of these membranes (especially SPEEK/PANI-1.5) was about four times lower than Nafion 117 membrane. Among the all SPEEK membranes synthesized in this study, SPEEK-1.5 appears to be more suitable for direct methanol fuel cell (DMFC) application considering optimum physicochemical and electrochemical properties, thermal stability as well as very low methanol permeability. Above all, the cost-effective and simple fabrication technique involved in the synthesis of such composite membranes makes their applicability quite attractive.     

凝胶型苯乙烯系离子交换树脂的强度及抗渗透性的影响因素研究 (I)

本文就单体组成中不同引发剂，链转移剂，环二烯，烯丙基类化合物和氧气等对凝胶型苯乙烯系阳离子交换树脂的强度和抗渗透性的影响进行了系统研究。结果显示，采用0．30％的过氧化2－乙基己酸叔丁酯（OT）和0．01％的过氧化苯甲酸特丁酯（CP）代替过氧化二苯甲酰（BPO作引发剂，或者加入0．02％的链转移剂十二烷基硫醇，均能够在一定程度上改善共聚物珠粒的结构均匀性，提高其合成的离子交换树脂的磨后圆球率和抗渗透性能。     

Implication of fractal geometry for fluid flow properties of sedimentary rocks

It is demonstrated that a certain amount of order can be extracted from an apparently random distribution of pores in sedimentary rocks by exploiting the scaling characteristics of the geometry of the porespace with the help of fractal statistics. A simple fractal model of a sedimentary rock is built, and is tested against both the Archie law for conductivity and the Carman-Kozeny equation for permeability. We demonstrate how multifractal scaling of pore-volume can be used as a tool for rock characterization by computing its experimentalf() spectrum, which can be modelled by a simple two-scale Cantor set.     

Gas permeability and permselectivity of fluorinated polybenzoxazoles

Gas permeability and permselectivity are investigated for polybenzoxazoles from bis(3-amino-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane (BAHHP) and aromatic diacid chlorides. Effects of thermal cyclization on the permeation properties are also investigated. The polybenzoxazole from BAHHP and 4,4′-(1,1,1,3,3,3-hexafluoroisopropylidene)dibenzoyl chloride (HFDB) displays high performance for CO₂/CH₄ separation ( $ {\rm P}_{{\rm CO}_2 } $ = 6.1 × 10^?9 cm³ (STP) cm^?1 s^?1 cm-Hg^?1, and $ {{{\rm P}_{{\rm CO}_2 } } \mathord{\left/ {\vphantom {{{\rm P}_{{\rm CO}_2 } } {{\rm P}_{{\rm CH}_4 } }}} \right. \kern-\nulldelimiterspace} {{\rm P}_{{\rm CH}_4 } }} $ = 38 at 35°C). The polybenzoxazole from BAHHP and 2,6-naphthalene dicarbonyl chloride displays high performance for H₂/CO or H₂/CH₄ separation ( $ {\rm P}_{{\rm H}_2 } $ = 2.4 × 10^?9 cm³ (STP) cm^?1 s^?1 cm-Hg^?1, $ {{{\rm P}_{{\rm H}_2 } } \mathord{\left/ {\vphantom {{{\rm P}_{{\rm H}_2 } } {{\rm P}_{{\rm CO}} }}} \right. \kern-\nulldelimiterspace} {{\rm P}_{{\rm CO}} }} $ = 71, and $ {{{\rm P}_{{\rm H}_2 } } \mathord{\left/ {\vphantom {{{\rm P}_{{\rm H}_2 } } {{\rm P}_{{\rm CH}_{\rm 4} } }}} \right. \kern-\nulldelimiterspace} {{\rm P}_{{\rm CH}_{\rm 4} } }} $ = 250). Permeation properties for the polybenzoxazole from BAHHP and HFDB are close to those for a polyimide of similar chemical structure. The permeation properties are discussed in connection with packing density and local segmental mobility. © 1992 John Wiley & Sons, Inc.     

多碎石沥青混合料路用性能

为了研究多碎石沥青混合料的路用性能，采用不同矿料组配条件下的沥青混合料类型，进行低温抗裂性、高温稳定性、路面渗水和路面抗滑性等项路用性能指标试验。结果表明，不同矿料组配条件下沥青混合料的路用性能变化显著，其中多碎石沥青混合料因其良好的矿料级配组成，使其具有优良的路用性质。     

特低渗储层应力敏感性及对油井产量的影响

对长6某特低渗储层进行了系统的应力敏感性实验研究.研究表明:该特低渗储层岩石的应力敏感程度在26%~80%的范围,岩石的渗透率越低,应力敏感性越强;原始条件下地下渗透率明显小于地面渗透率,它们之间有较好的线性关系;储层岩石应力敏感伤害后,储层岩石的渗透率不能立即恢复,最终渗透率恢复率在68.6%~100.0%,岩石渗透率越高,渗透率恢复值越大;当岩石的渗透率小于0.5×10-3μm2时,储层岩石的应力敏感性明显增强.模型预测表明,当地层压力降低5MPa时,该储层岩石的应力敏感性对油井产量的影响在8.6%~35.7%,渗透率越低下降幅度越大.     

低速非达西渗流储层产能评价

在低渗透油藏低速非达西渗流模型的基础上，应用具有启动压力影响的不稳定产能评价方法，实现了将地层参数代入相关方程计算产量随时间的变化规律及不稳定IPR曲线，对于工业油层预测了生产时间为180天时油井的极限产量(流压为0．101MPa时的产量)，对这类井的开发投产具有重要的指导意义。