A novel approach for evaluation of polymeric interface materials for chemical sensors using alternate indirect methods

The heart of a chemical sensor based on bulk or surface acoustic wave devices is a polymer‐coated piezoelectric substrate that selectively sorbs and concentrates the target analyte vapors. The development of such sensors often necessitates the screening and evaluation of suitable polymeric interface materials meeting the specified sensitivity and selectivity toward the analytes of interest. The magnitude and dynamics of sorption–desorption of the vapors in the polymer and the extent of polymer–vapor interactions largely determine the performance of a sensor. The standard protocol used for the purpose is rather tedious, involving the generation and calibration of individual analyte vapors, with stringent control on temperature, humidity, and test parameters. This article outlines four different alternative techniques based on mass uptake of the analyte vapors, on its partitioning in polymers, or both, which in combination can determine the characteristics of an interface material used for coating a piezoelectric substrate in acoustic wave‐based chemical sensors. These methods were applied to poly(ethylene maleate), a representative interface material. The analytes ranged from volatile organic chemicals to sarin—a chemical warfare agent—and its simulant, dimethyl methylphosphonate. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3428–3432, 2004     

气液两相流界面多尺度问题可计算性研究进展

气液两相流复杂多变的界面结构在瞬态时间上具有宽广的空间尺度范围.界面多尺度问题涉及化工领域、核安全领域以及其他多个领域,其可计算性是当前国内外气液两相流领域的研究焦点之一.分析了欧拉体系下处理气液两相流相界面不连续性的两种基本模型以及湍流模拟方法对界面结构的影响.针对离散流界面尺度分布性和混合流界面跨尺度性两类多尺度问题,分析了可计算性研究面临的困境,将其归因于网格尺度的约束、几何及物理边界的缺失.重点归纳了混合流界面跨尺度性问题的计算方法以及典型应用.最后对气液两相流界面多尺度问题提出了应对策略及研究趋势,为此类问题研究提供有益的参考.     

冰水界面动态结构的分子动力学模拟研究

为了探究结冰过程冰水界面结构的动态复杂性,利用分子动力学模拟方法构建微观的冰水两相共存模型,研究了冰水两相界面结构随温度和晶面的变化规律。结果表明,当冰水两相达到平衡时,冰水界面结构中存在无序水分子和有序冰晶结构的可逆动态转变,造成了界面结构的不均匀性。在改变环境温度和晶面类型时,冰水界面结构表现出不同的分布规律。在相同的温度下,一次棱柱面和二次棱柱面的界面层厚度比基面的略薄,而棱柱面水分子排列的有序性强,且存在分子间氢键的三维网络重组。当过冷度较大时,界面结构趋于六元环排列的有序状态,界面内无序水分子增多,同时水分子在界面层内的停留时间增长。从分子尺度上阐明了冰水体系界面结构的变化规律,对理解结冰过程和发展控冰技术具有一定的指导意义。     

OPEO表面活性剂在油水界面的分子动力学模拟

辛基酚聚氧乙烯醚(OPEO)是常用的非离子型表面活性剂,可以显著降低油水体系的界面张力。选择醋酸乙烯酯/水体系,通过改变OPEO中氧乙烯基的数量,采用MS7.0软件中的分子动力学(MD)模拟方法,在常温常压下对油/表面活性剂/水体系的界面生成能、界面厚度等指标进行测定,结果表明,氧乙烯基数量为12时,OPEO的界面生成能较高,降低醋酸乙烯酯/水体系界面张力的能力较好。     

New approaches to determine the interface height of fire smoke based on a three-layer zone model and its verification in large confined space

Large confined space has high incidence of fires, which seriously threatens the safety of people working there. Understanding the distribution of smoke in such large space is critical to fire development prediction and smoke control. Three improved methods for the stratification interface prediction of fire smoke are developed, including of improved intra-variance, integral ratio and N-percentage methods. In these methods, the interface height is determined by the vertical temperature distribution based on a three-layer smoke zone model, which is an improvement of a two-layer zone model. Thereafter, the three improved methods are applied to several typical fire cases simulated CFD to predict the smoke interface, and their applicability and reliability are verified by comparison of the smoke stratification results with the filed simulation results. Results show that the three improved methods can effectively determine the location of the three-layer zone model's interface, and they have the ability to predict smoke interface for fires with different fire source types and ventilation conditions.     

铜基片静态气液界面腐蚀规律的实验

气液两相界面腐蚀广泛存在于日常工业中。因气液相界面存在不稳定特性,迄今对于相界面处腐蚀的研究多针对不断变化的界面位置附近,分析一段时间内的累积腐蚀效果。本文向液相内注入一定体积的气泡,维持气液界面在金属铜壁面的稳定以及气液相界面和液相主体浓度近似恒定;在含不同Cl^-浓度的溶液中,通过电化学方法对比有无相界面的腐蚀规律,并根据数据深入分析相界面处的腐蚀机理。结果表明：引入气液界面导致铜试样腐蚀电位升高、腐蚀电流增大,腐蚀更严重;气液界面处由于引入微观界面能差腐蚀、宏观氧浓差电池腐蚀的作用显著增大了试样的腐蚀电流,使得在整个溶液浓度范围内含界面的铜腐蚀电流均高于不含界面的腐蚀电流,同时在铜表面留下清晰的界面腐蚀线;通过对界面腐蚀电流的剥离,包含液相主体腐蚀部分时无论有无界面的铜腐蚀速率均随Cl^-浓度的升高呈现先增大后减小的趋势,而去除液相部分影响的单独界面腐蚀电流则随Cl^-浓度升高而增大。     

In situ measurement of water at the organic coating/substrate interface

In situ and quantitative information on the water layer at the organic coating/substrate interface is crucial for understanding and preventing the failure of organic coating systems. A technique, based on a two-layer model derived rigorously from internal reflection theory, has been developed for measuring in situ the thickness and amount of the water layer at the organic coating/substrate interface. The technique gives new insight into the processes by which water degrades the coating/substrate bonds. In this technique, a transparent or an opaque organic coating of sufficient thickness is applied to an internal reflection element (IRE) with or without a thin metallic film, which is used as the substrate. A water chamber is attached to the organic-coated specimen. After adding water to the chamber, Fourier transform infrared-multiple internal reflection (FTIR-MIR) spectra are taken automatically at specified time intervals without disturbing the specimens or the instrument. Water uptake in the coating and FTIR-MIR spectra of water on the coating-free substrate are also used for the analysis. Examples of clear and pigmented coatings on untreated and treated substrate surfaces are given to demonstrate the technique. Results of water accumulation at the coating/iron interface with and without applied electrical potentials are given. In addition to measuring water at the coating/substrate interface, the technique provides a means for studying the transport of water through a coating adhered to a substrate. Information on water at the interface and its transport properties through coatings applied to a substrate is valuable for interpreting corrosion, blistering and delamination of organic coating systems, and for developing models for use in predicting the serivce lives of protective coatings.     

钢/玻璃钢耐腐机车容器界面力学性能试验研究

本文针对机车用钢/玻璃钢复合容器提出了冷弯、弯曲性能及疲劳性能试验,以考察钢/玻璃钢界面处的性能.试验结果表明界面性能能满足使用要求,并测定了容器受冲击时界面不脱壳的冷弯角度.     

热界面材料热导率和接触热阻的测试

热界面材料通常用于降低电子器件中固体界面的热阻。热界面材料的性质, 如热导率、界面材料与固体表面间的接触热阻, 对于电子器件的散热分析非常重要。然而, 这些参数通常难以获得。依据ASTM D-5470测试标准, 搭建了一个热界面测试系统。通过该系统测试了硅油和导热硅脂的热导率, 以及它们与固体基板间的接触热阻。经分析, 测试热导率和接触热阻的相对误差分别小于11.3%和41.3%。     

固/液界面纳米气泡形成及稳定性研究进展

固/液界面上形成界面纳米气泡（SNBs）,广泛存在于电催化、流体输送、矿物浮选等领域中,并影响各个过程的效率,因此明确其形成及稳定机理对过程调控具有重要意义。首先从实验观察和模拟计算两个角度,对纳米气泡的研究方法进行探讨,综述了不同气体类型、固体界面性质、液相添加剂下纳米气泡的形成规律。由于目前纳米气泡形成后的稳定性尚不十分明确,主要总结了现阶段广为接受的接触线钉扎稳定机制,并分析了该领域的研究现状。此外,考虑到离子液体作为重要的化工溶剂,概述了该体系中微纳气泡的相关研究。最后简要对未来工作进行了展望,以期为离子液体体系中纳米气泡的研究提供新思路。     

秸秆纤维增强热塑性树脂基复合材料界面改性研究新进展

秸秆纤维增强热塑性树脂基复合材料是一种用途广泛的新型环保性材料。复合材料的界面相容性会直接影响复合材料的性能,界面改性技术的研究成为近年来研究的热点。本文综述了国内外对秸秆纤维增强热塑性树脂基复合材料界面改性技术的研究现状和新进展,叙述了对于秸秆纤维的几种典型表面处理方法的研究进展;重点分析了等离子体处理和生物酶处理这两种新型处理方法在秸秆表面预处理中的应用情况,并着重阐述了以马来酸酐接枝聚烯烃为主的界面相容剂和以硅烷、钛酸酯为主的低分子量偶联剂对复合材料界面改性效果的影响。此外,论文简要分析了秸秆/树脂复合材料界面改性技术的发展趋势,指出深入研究针对秸秆纤维的复合处理方法以及开发高效、环保和高性价比的界面改性剂是未来进一步改善秸秆/树脂复合材料应用性能的关键。     

Theory of the double-layer effect on the rate of charge transfer across an electrolyte/electrolyte interface

Effect of the electric double-layer structure on the rate equations of charge (ion or electron) transfer across an electrolyte/electrolyte solution interface is discussed. The electric double layer is considered as composed of the inner layer sandwiched by two diffuse layers in both side. The charge transfer reaction is considered as taking place between two chemical species at the planes of contact of the inner layer with the two respective diffuse layers. A steady-state ionic transport in the diffuse layers (Levich correction) is assumed. Two ideal processes; inner layer rate-determining process and diffuse layer rate-determining process are addressed.     

State-of-the-art review of interface bond testing devices for pavement layers: toward the standardization procedure

During the past thirty years, interface bonding between pavement layers has been a topical subject worldwide to research. In this context, many researchers have developed and utilized their own devices to investigate the properties of pavement interfaces. In the absence of an international standard procedure for interface bonding, it is inevitable that testing results are not comparable in all cases. In addition, various conducted studies reveal that parameters such as temperature, loading conditions, materials and so on exert an influence on interface properties. This paper aims to deal with the matter effectively via a thorough and comprehensive review of interface bond testing to lay the groundwork for standardization procedure. For this purpose, first, a general overview of interface bond function and its impact on pavement performance is presented. Then, different types of interface bond test methods according to loading conditions are explained; furthermore, the configuration of various setups is discussed and their function is compared together. Finally, given the prior experiences, a framework for a methodical approach to a standard evaluation of pavement interfaces is presented.     

非球形固态夹杂物穿过钢-渣界面行为研究

为了解释炼钢过程中固态夹杂物比液态夹杂物更易去除的现象,基于分离过程中受力分析,建立了描述八面体和板状夹杂物穿过钢-渣界面行为的数学模型。与传统数学模型相比,本模型考虑了夹杂物周围钢-渣界面变形引起的界面变形阻力。同时,采用该模型研究了各相(钢液、渣和夹杂物)界面张力和顶渣黏度等因素对固态夹杂物穿过钢-渣界面分离行为的影响。结果表明,若忽略固态夹杂物溶解过程,钢液、顶渣和夹杂物体系释放的界面自由能是固态夹杂物穿过钢-渣界面的驱动能,且该动能已足够保证多数固态夹杂物穿过钢-渣界面进入渣层。固态夹杂物溶解过程释放的吉布斯自由能远大于该过程释放的界面自由能,固态夹杂物接触钢-渣界面的瞬间被顶渣吸收去除。     

基于表/界面调控的金属氧化物半导体光催化剂的理性构筑

近年来半导体光催化作为一种绿色技术在解决环境问题和提供可再生能源方面获得了广泛关注,然而较低的催化效率限制着它的实际应用。合理设计金属氧化物半导体的表/界面结构,是提升光催化剂性能的有效手段。对近年来半导体光催化剂的表/界面结构调控以及构-效关系的研究进行了梳理,介绍了在单一组分体系中利用晶面效应优化光催化性能的可行措施。在此基础上,总结了晶面/界面结构调控在复合光催化剂体系中的应用。最后,总结了该领域面临的挑战与未来的前景。     

基于四叉树直角坐标网格的运动界面追踪方法

运动界面的追踪是两相流模拟中需要解决的主要问题之一。基于四叉树直角坐标网格实现了Level set界面追踪方法和网格的局部自适应控制。通过模拟3个给定速度场（平移流场、旋转流场、剪切流场）的运动界面追踪问题,证明了自适应四叉树直角坐标网格与Level set方法结合的优势。     

模拟变形液滴和气泡运动的改进水平集算法

An improved level set approach for computing the incompressible two-phase flow with significantly deformed free interface in presented.The control volume formulation with the semi-implicit method for pressure-linked equations consistent(SIMPLEC)algorithm incroporated is used to solve the governing equations on a staggered grid.Several improvements concerning the convergence and numerical stability.The motion of a bubble or drop in a liquid with large density ratio,viscosity ratio and surface tension in numerically simulated.The computational results are in good agreement with the reported experimental data.     

Extraction of rate-dependent fracture properties of adhesive interface involving large-scale yielding

Interface debonding is one of the major failure modes for the adhesive joints of polymer–matrix composites. The interfacial fracture properties of adhesive interfaces involving large-scale yielding is difficult to determine. A hybrid method that combines modified data reduction and inverse analysis was used to determine the fracture energy of the composite propellant/insulation interface at different loading rates. The modified data reduction adopts effective crack length to account for the effect of the fracture progress zone and avoid monitoring the crack length. These estimated values of the fracture energy were then calibrated by inverse analysis based on the Hooke–Jeeves algorithm in which the interface layer is characterized by a cohesive zone model. The whole process of inverse analysis is conducted automatically without any intervention by procedures. Experimental and numerical results indicate that the proposed data reduction provided fracture energy sufficiently similar to those obtained by the inverse analysis. Moreover, the fracture energy of the propellant/insulation interface was found to rely heavily on the loading rate with a non-monotonic trend.     

Investigating the strength of Ti/TiB interfaces at multiple scales using density functional theory,molecular dynamics,and cohesive zone modeling

Titanium/titanium boride (Ti/TiB) composites are interesting technological materials with prospective applications in the aerospace, automotive, and biomedical industries. However, not much has been studied about the failure mechanisms of these composites. This article thoroughly investigates the adhesion and strength of two well-known Ti/TiB interface variants formed during the production of Ti/TiB composites below and above 910 °C, respectively. The studies were carried out using different theoretical methods at multiple scales, including density functional theory (DFT), molecular dynamics (MD), cohesive zone modeling (CZM), and the finite element method (FEM). First, we employed DFT to investigate the interfacial adhesion and strength of the selected planes. Then, MD simulations were utilized to study the misfit dislocation networks and derive interfacial CZMs for FEM modeling and simulation of composites. Our FEM simulations showed that the Ti/TiB interface has sufficient strength to transfer the shear load from Ti to TiB without debonding at room temperature. The results have confirmed the same phenomenon observed in some experimental studies and interpreted this phenomenon from a multiscale point of view. The research findings can be used in quantifying the failure stress of TiB whiskers directly from tension tests on Ti/TiB composites by ruling out the possibility of interface debonding.     

Interfacial Characteristics of Sisal Fiber and Polymeric Matrices

Sisal-fiber-reinforced composites, as a class of eco-composites, have attracted much attention from materials scientists and engineers in recent years. In this article, the effects of fiber surface treatment on fiber tensile strength and fiber-matrix interface characteristics were determined by using tensile and single fiber pullout tests, respectively. The short beam shear test was also employed to evaluate the interlaminar shear strength of the composite laminates. Vinyl ester, epoxy, and high-density polyethylene (HDPE) were chosen as matrix materials. To enhance the interfacial strength, two kinds of fiber surface-treatment methods, namely, chemical bonding and oxidisation, were used. The results obtained showed that different fiber surface-treatment methods produced different effects on the tensile strength of the sisal fiber and fiber-matrix interfacial bonding characteristics. Hence, valuable information on the interface design of sisal fiber-polymer matrix composites can be obtained from this study.