纯气体在非晶态高分子膜内的吸收机理模型(Ⅰ)理论

提出了一个描述非晶态高分子膜结构特征的模糊数学模型.基于这一模型,作者认为,橡胶态膜内也存在“特征微孔”,并且比玻璃态膜更多.该两种膜的主要吸收机理都是“充孔”机理.运用分子热力学原理,导出了一个普遍化吸收机理模型.本模型假设,非晶态高分子膜内存在两种“格位”,它们对渗透分子的作用各不相同.适用于玻璃态膜的双方式吸收模型和适用于橡胶态膜的Henry定律在这一模型中得到了统一,模型参数也从分子数量级上获得了明确的解释.     

碳酸锂碳化反应过程分析与机理探讨

用双膜理论揭示了碳酸锂气、液、固三相碳化反应的规律.从化学反应动力学和工程学的角度,分析了碳化反应的过程并对反应的机理进行了探讨,对实验结果进行了理论解释,为优化工艺参数提供了理论依据,对实际生产也具有一定的参考价值.     

陶瓷膜生物反应器处理生活污水膜污染机理的研究

采用一个经典模型描述了陶瓷膜生物反应器处理生活污水过程中的通量衰减,通过模型参数分析了膜的污染机理。分析结果表明,孔径为50、200和500nm的陶瓷膜主要由“部分孔堵塞”机理、“完全孔堵塞”机理和“部分孔堵塞”机理控制。     

膜生物反应器中膜污染行为及机理的探究

对MBR系统中膜沉积层控制的污染行为和机理进行了详尽的阐述,采用不同膜考察了浸没式MBR处理模拟焦化废水的膜污染发展过程,在不同操作模式(恒压、恒流条件)下探究了MBR系统膜污染机理.结果表明:沉积泥饼层控制的膜污染过程中,污泥的压缩性指数、膜特性及通量等是直接影响膜污染的重要因素.并可用考虑污泥压缩性指数及错流影响的模型预测沉积层控制的膜污染过程.     

铝矿赤泥碱回收的动力学及机理研究

悬浮碳化工艺是碱性赤泥常压下回收碱的新工艺.以该工艺为研究对象,用双膜理论揭示了在赤泥浆液中进行的气、液、固三相碳化反应的机理,并从化学反应动力学的角度对整个碳化反应过程进行了探讨和研究.阐述了工艺中不同碳化反应阶段的反应行为,给予了理论上的解释,同时对工艺的4个影响因素(反应时间、反应温度、液固比和二氧化碳通入量)进行了理论分析.研究表明,该回收过程的控制步骤是二氧化碳和碱的溶解与扩散传质,4个因素对回收工艺本身有较大影响.对于新工艺的反应行为和机理的分析为悬浮碳化法顺利实现工业化提供了重要的理论依据,并为同类工艺提供了可靠的理论研究方法.     

液膜脱酚的综合传质模型

本文研究了液膜传质过程中的各种复合因素,提出描述该过程的综合传质模型.考虑到液滴内外传质阻力及膜破裂等因素的影响,本模型将著名的“渐近前沿模型”作适当调整.模型参数k_o和B_m由Powell优化方法最优拟合实验值决定.实验结果证实本文所建议的传质机理模型比较符合实际,并具有适用的弹性.     

纯气体在非晶态高分子膜内的吸收机理模型(Ⅰ)理论

提出了一个描述非晶态高分子膜结构特征的模糊数学模型.基于这一模型,作者认为,橡胶态膜内也存在“特征微孔”,并且比玻璃态膜更多.该两种膜的主要吸收机理都是“充孔”机理.运用分子热力学原理,导出了一个普遍化吸收机理模型.本模型假设,非晶态高分子膜内存在两种“格位”,它们对渗透分子的作用各不相同.适用于玻璃态膜的双方式吸收模型和适用于橡胶态膜的Henry定律在这一模型中得到了统一,模型参数也从分子数量级上获得了明确的解释.     

碳酸锂碳化反应动力学研究

研究了碳酸锂碳化反应动力学,利用气-液-固三相机械搅拌反应器,通过监测反应过程中CO2气体的压力变化与消耗情况,计算出反应速率,简化了分析步骤.实验发现,在实验范围内,得到的碳化反应速率随时间的变化曲线均经历一个非单调的从大变小,再增大,后又减小直至为0或趋于稳定的变化过程.通过反应机理分析,借助气-液传质的双膜理论模型,导出了碳酸锂碳化反应动力学方程,并根据动力学方程解释了实验现象.     

炭分子筛膜气体分离传递机理研究的新进展

炭分子筛膜由于其本身具备的独特优势以及其在气体分离方面的应用潜力,已引起了世人的关注.但对炭分子筛膜分离机理特别是传递过程机理研究的不足限制了其发展.本文介绍炭分子筛膜气体分离机理特别是传递过程机理研究的最新进展,包括针对制备方法不同所建立的气体传递机理模型,如Maxwell模型和Bruggeman模型;详细介绍了两种孔结构模型平行阻力模型和阻力串联模型.在此基础上,分析了各模型中存在的问题和不足,认为需要对炭分子筛膜进行进一步的完善并建立合理的传递机理模型,才能推动炭分子筛膜用于气体分离的进程.     

双极膜分离技术及应用进展

双极膜通过对水解离具有的催化效应,能够使水中的盐重新转变为酸和碱,在环境保护和资源回收等领域发挥着越来越大的作用。本文解析了双极膜的“三明治”结构特点、发展历程及发展趋势、制备工艺技术,阐述了双极膜催化水解离机理的3个模型：第二Wien效应模型、化学反应模型以及中和层模型。探究了双极膜电渗析及与其它化工过程耦合技术在不同领域的应用,其中包括酸碱生产领域、资源分离回收领域以及污染控制领域等。分析了双极膜的具体应用过程中存在的局限性并展望了双极膜在水解制氢、液流电池方面的应用前景。指出双极膜将朝着与传统化工过程、新型液流电池等系统集成化、规模化方向发展,成为多种化工应用领域的重要组件。     

Microstructures and electrothermal characterization of aromatic poly(azomethine ether)-derived carbon films

We report the microstructural evolution and electrothermal properties of aromatic poly(azomethine ether) (PAME)-derived carbon films, which were fabricated by a facile spin-coating and following carbonization at different temperatures of 300–1,000°C. For the purpose, poly[3-(4-nitrilophenoxy)phenylenenitrilomethine-1,3-phenylenemethine] (mPAME) with a high residue of ~56.4 wt% after carbonization at 1,000°C was synthesized for a polymeric precursor for carbon films. The X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction analyses revealed that the molecular structures of mPAME films changed into an intrinsically nitrogen-doped graphitic structure, dominantly at the carbonization temperatures of 800–100°C. The electrical conductivity increased considerably from ~10⁻⁷ S/cm for mPAME-derived films fabricated at 300–700°C to ~10⁰ S/cm for the film carbonized at 800°C to ~10¹ S/cm for the films carbonized at 900–1,000°C. Accordingly, mPAME-derived carbon films, which were carbonized at 900–1,000°C, exhibited excellent electrothermal performance, such as rapid temperature responsiveness, high maximum temperatures, and high electric power efficiency to relatively low applied voltages of 5–13 V.     

Infra-red characterization of carbonization of Si surfaces by gas source molecular beam epitaxy

The carbonization and epitaxial growth of cubic SiC films on Si(100) substrates using C₂H₂ and solid Si sources has been investigated by means of infra-red Fourier transform spectroscopy. The carbonization of the Si surface is performed under continuous C₂H₂ flux in two steps: an ordinary process, plus an increase of the substrate temperature to its final value. Subsequent epitaxial films were grown under simultaneous supply of elemental Si and C₂H₂ gas beam. Infra-red reflectivity spectra of samples under different conditions are reported and permit the direct verification for the presence of SiC in carbonized layers, measure the thickness of the films and evaluate their quality.     

Catalytic effect of nickel under carbonization of polyimide films

In attempt to produce graphite films with high crystallinity by heat-treatment at temperatures lower than 3000 °C, the catalytic effect of nickel was investigated for carbonization of polyimide films prepared by mixing polyamic acid with nickel particles. The three-layered polyimide film was prepared to obtain graphite films with thickness beyond 100 μm. The middle layer composed of polyimide with nickel particles. The thickness of each layer was 50 μm and the film thickness became 150 μm. The carbonization was done at ca. 1600 °C for 5 h. The morphology of the carbonized films was observed by scanning electron microscopy. The graphitization degree was investigated on the basis of X-ray diffraction intensity distribution from the (0 0 2) plane. The analysis was done in terms of the comparison between the experimental and theoretical diffraction intensity curves. The theoretical calculation was carried out by using a concept for the para-crystalline theory proposed by Hoseman and Bagchi from the viewpoint of the lattice fluctuation of the c-axis.     

Graphene induced carbonization of polyimide films to prepared flexible carbon films with improving-thermal conductivity

Carbon films prepared by polyimide (PI) films treated under 1500°C exhibit favorable thermal conductivity. However, the bonds of carbon films will fracture and recombine which will cause shrinking and forming defects. The flexibility of the carbon films will be greatly reduced, and then affect the application of the carbon films in the field of thermal conduction. When the films prepared by the graphene oxide/polyimide (GO/PI) composite films and the reduced graphene oxide/polyimide (rGO/PI) composite films, respectively, rGO and GO can fill the defects, then increasing the flexibility of the carbon films and inducing the carbonation process. Because of the high thermal conductivity and the six-membered ring structure of rGO and GO, the carbonization temperature will decrease and save costs. When the composite films treated under 1500°C, the thermal conductivity increases with the content of rGO and GO. There are connections between PI and graphene. As the amount of rGO and GO increases, the strong interactions between the rGO or GO and PI lead to contact that enhances its thermal conductivity. However, the rGO and GO have different effects on the films flexibility and thermal conductivity and the differences will be described in the article.     

Growth mechanism of 3C-SiC(lll) on Si without carbonization process

We have used rapid thermal chemical vapor deposition (RTCVD) technique to grow epitaxial SiC thin films on Si wafers without carbonization process by pyrolyzing tetramethylsilane (TMS). The growth rate of SiC films increases with TMS flow rate and temperature, but it decreases with temperature at higher TMS flow rates. The XRD spectra of the films indicate that the growth direction is along the (111) direction of β-SiC. IR and RBS measurements have been employed to analyze the chemical composition of the films. At 1100°C TMS molecules dissociate almost completely into Si atoms, CH₄ and C₂H₂ gases. The growth mechanism of SiC films on Si substrates without carbonization process has been proposed based on the analyses by TEM and QMS.     

Electromechanical deformation and failure of multilayered films

Layer thickness was found to have a significant effect on the irreversible electromechanical deformation and the failure mechanism in polycarbonate (PC)/poly (vinylidene fluoride) (PVDF) multilayered films when subjected to an electrical impulse in a DC needle-plane configuration. Three distinct regions of behavior were observed. Region I comprised thick layer systems that exhibited only irreversible center deformation. The improvement to failure resistance compared to the monolithic films was attributed to the interphase between the two components. Region II films with an intermediate layer thickness showed both an irreversible center deformation and a treeing mechanism which were observed to simultaneously occur. The surface treeing mechanism, similar to the lightning treeing phenomena in nature, occurs only at impact rates. The tree morphology showed large amounts of plowing, indicating that this damage mechanism can dissipate a large amount of energy prior to electromechanical fracture of the film. Region III films comprise ultrathin layers in the nanoscale and showed no treeing. The unique interphase region between these ultrathin layers was estimated to be at least ten percent of the overall layered structure. These films behaved similar to monolithic materials with improved electromechanical failure characteristics. This work complements the enhanced dielectric performance of multilayer films observed in earlier investigations.     

Orientationally ordered and patterned discotic films and carbon films from liquid crystal precursors

This article demonstrates techniques for fabricating novel organic and carbon films, in which liquid crystal surface anchoring and flow are exploited to precisely control molecular structure (in organic films) or crystal structure (in carbon films). Surface anchoring states were first measured for AR mesophase on spin-coatable organic resins, including commercial polyimide and photoresist. These results were used to develop a lithographic technique for ordering AR surfaces in preprogrammed orientational micropatterns. AR was also processed into radial or star symmetry films by forced spreading combined with edge-on anchoring templates. Additional thin films were prepared from alternative liquid crystalline precursors composed of sulfonated polyaromatic dyes. These disk-like planar molecules undergo massive π-stacking in aqueous solution to form rod-like aggregates. At high concentrations or on surfaces, these rods or molecular columns align by repulsive interactions (lyotropic behavior), giving raise to a transverse alignment of the stacked polyaromatic disks. Here the lyotropic dye indanthrone disulfonate is used to make fully dense ordered carbon films by spin coating or Meyer-bar coating thin films on quartz followed by direct carbonization (without oxidative stabilization). These films exhibit surfaces rich in graphene edge-sites and are either anisotropic unidirectional (by bar coating) or multi-domain with long-range isotropy (by spin coating).     

塑料地膜的应用及改进

塑料地膜覆盖技术在给农业带来显著经济效益的同时,也对土壤和环境造成了严重污染,采用光降解薄膜是减轻这些污染的有效途径。本文叙述了塑料薄膜对生长作物的作用以及残留薄膜对环境和农业耕作的危害,同时,也对光降解机理、光降解薄膜的生产和应用做了简要介绍。     

新型开口爽滑剂母料在聚烯烃薄膜中的应用

介绍了聚烯烃薄膜开口爽滑剂的分类、作用机理及新型开口爽滑剂母料在聚烯烃薄膜中的应用。并对未来的开口爽滑剂发展提出了思路。     

Numerical simulation on flow behavior of twin‐liquid films over a vertical plate with an open window

A novel element for gas–liquid contact, a plate with rectangular windows was designed to enhance absorption process. Coexistence and interaction of wall‐bounded films and confined free films named as “twin‐liquid films” were observed on the plate. Volume of fluid (VOF) method was used to simulate its flow behavior. Flow phenomena such as flow around a step‐in, jet impingement, varicose waves, and sinuous waves were observed. Different from thin films flow on an unperforated plate, larger mean velocity, thinner film thickness, more intensive capillary waves, and stronger vorticity on the free surfaces were detected inside the window, and the disturbances could propagate over the whole plate. Three‐dimensional simulation results generally agreed with our experimental observations and further demonstrated complex wavy structures both inside and outside the window. The results would broaden traditional knowledge of liquid films flow and clarify the mechanism of mass transfer intensification for the plate with windows. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1458–1468, 2018