聚苯醚的化学改性

综述了聚苯醚(PPO)的化学改性,主要包括端基改性和主链改性,改性后的产物广泛应用于PPO的膜工业中,同时可以用作PPO合金的增容剂。     

聚苯醚的改性

综述了改性聚苯醚（ＰＰＯ）的研究开发及其性能和应用情况,并提出了ＰＰＯ的发展特点和前景。     

玻纤增强聚苯醚合金的制备与性能研究

通过熔融挤出的方法制备了不同玻纤含量增强的聚苯醚合金（MPPO）,并对复合材料的力学性能和热性能进行了详细的研究。通过DSC分析测试发现弹性体苯乙烯-乙烯-丁烯-苯乙烯嵌段共聚物（SEBS）与聚苯醚合金（PPO／HIPS）制备的复合材料只有一个明显的玻璃化转变温度Tg,说明SEBS与聚苯醚合金有着良好的相容性,SEBS的加入可明显改善聚苯醚合金的缺口冲击强度。此外,复合材料随着玻璃纤维含量的增加,其力学性能和热变形温度得到了明显的提高,并达到与国外进口同类材料性能相当的水平。     

聚苯醚改性环保型玻纤增强酚醛塑料的研究

使用一种改性剂XPY，在酚醛树脂的合成过程中成功引入了聚苯醚，制得了一种新的改性环保型酚醛塑料。采用扫描电镜（SEM）和热失重分析（TGA）等手段对这种改性酚醛塑料进行了研究和分析，发现改性后的酚醛塑料具有优异的力学性能，并且耐热性和耐磨性也比未改性的酚醛塑料有较大提高。     

Removal of N‐butanol from aqueous solutions by ion–exchange membranes containing organic counterions

The pervaporation of aqueous butanol solutions was investigated using thin‐film composite membranes composed of a poly(vinylidene fluoride) substrate coated with a sulfonated poly(2,6‐dimethyl‐1,4‐phenelene oxide) polymer. The polymer was ion‐exchanged with quaternary ammonium cations having aliphatic substituents of various chain lengths. The pervaporation of aqueous n‐butanol solutions using these membranes gave a permeate more concentrated in n‐butanol; therefore, they were alcohol‐selective. The separation factor increased and the permeate flux decreased as the chain lengths of the aliphatic substituents were increased. Hence, the mass‐transport properties of such membranes can be controlled or altered to yield some desired permselectivity by the introduction of a proper counterion. It was observed that the n‐butanol flux was small relative to the total flux and, therefore, the water flux dominated the total permeate flux. The degree of swelling of the membranes and its effect on membrane performance was investigated as well. As the n‐butanol content was increased, the swelling of the membranes increased greatly. High membrane swelling caused a reduction in the separation factor. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 47–58, 1999     

分子筛膜渗透蒸发技术研究进展

概述了渗透蒸发膜分离过程和分子筛膜的优点,重点综述了沸石分子筛膜在渗透蒸发中的传输机理和传质模型,以及温度、压力、组成等对渗透蒸发膜分离性能的影响因素,介绍了分子筛膜渗透蒸发技术在有机溶剂脱水、水中脱除有机物和有机混合物分离等方面的应用,展望了分子筛膜在渗透蒸发膜分离技术中的发展方向。     

Mesoporous Glass Membranes as Model Systems to Study Gas Diffusion through Porous Media

Porous glass monoliths are suitable model systems to study pore size‐related effects in gas diffusion. Here, mesoporous glass membranes with different surface properties and pore diameters covering the lower mesopore range were synthesized and used to study gas permeation of adsorbable and non‐adsorbable gases. Dynamic single gas permeation measurements were performed using a modified Wicke‐Kallenbach cell. Chemical surface modification of the inner surface of the membranes resulted in altered adsorption and diffusion properties.     

聚氨酯／苯乙烯互穿网络膜的实验研究

以亲水性强的聚乙二醇（PEG）和甲苯二异氰酸酯（TDI）为原料制备聚氨酯预聚体，而由苯乙烯（ST）和二乙烯苯（DVB）制得交联聚苯乙烯（PS），得到的渗透汽化膜可以进行水／乙醇混合液的分离，通过测试膜的性能，结果显示膜的分离效果较好，运用SEM对膜进行了表征。     

热重法评估聚芳醚的活化能

阐述了近期对于快速热氧老化的评价方法,采用热重点斜法和改进的Kinssinger方法计算改性聚芳醚的氧化活化能,同时展开低温常规长期热氧老化试验,比较快速评价方法间和常规热氧老化试验方法的差异,通过数据分析可以发现常规老化活化能与改良Kinssinger方法推导的活化能之间存在比较好的对应关系。     

凝胶色谱法测试聚苯醚平均分子量及分子量分布

建立凝胶色谱法测试聚苯醚平均分子量及分子量分布。采用凝胶色谱仪,色谱柱为Waters HR1、HR2、HR4E,检测器为示差折光检测器,流动相为甲苯,流速为1 mL/min,柱温为40℃。此方法快速、准确、操作方便,测试数据有良好的重复性和再现性。并对影响测试结果的各因素进行分析。     

热固性聚苯醚树脂在高频印制电路板上的应用

介绍了高频印制电路板基材的介电性能要求和热固性聚苯醚树脂基材的制备 ,详细讨论了制备热固性聚苯醚树脂的两条技术路线及其树脂体系的特性 ,以及热固性聚苯醚树脂基覆铜板的特性 ,并简要介绍了热固性聚苯醚树脂基覆铜板的应用情况。     

氰酸酯树脂/聚苯醚/纳米二氧化硅电子封装材料固化动力学研究

采用硅烷偶联剂表面处理过的纳米二氧化硅作为无机填料改性氰酸酯树脂/聚苯醚固化体系,并利用非等温差示扫描量热法研究了氰酸酯树脂/聚苯醚/纳米二氧化硅电子封装材料的固化动力学。结果表明,氰酸酯树脂/聚苯醚/3%纳米二氧化硅固化体系的凝胶温度为150℃、固化温度为181℃、后处理温度为239℃;固化动力学参数表观活化能为15.46kJ/mol、反应级数为0.82、频率因子为38174.38s-1;加入纳米二氧化硅可以降低氰酸酯树脂/聚苯醚固化体系的表观活化能,使其固化反应可以在较低温度下进行。     

Recent Developments and Applications of Ionic Liquids in Gas Separation Membranes

Flue gas emissions and the harmful effects of these gases urge to separate and capture these unwanted gases. Ionic liquids due to negligible vapor pressure, thermal stability, and wide electrochemical stability have expanded its application in gas separations. A comprehensive overview of the recent developments and applications of ionic liquid membranes (ILMs) for gas separation is given. The three general classifications of ILMs, such as supported ionic liquid membranes (SILMs), ionic liquid polymeric membranes (ILPMs), and ionic liquid mixed‐matrix membranes (ILMMMs) along with their applications, for the separation of various mixed gases systems is discussed in detail. Furthermore, issues, challenges, computational study, and future perspectives for ILMs are also considered.     

Impact of Layered Perovskite Oxide La0.85Yb0.15AlO3 on Structure and Transport Properties of Polyetherimide

This study aims to improve properties of Ultem^® polyetherimide (PEI) by incorporating up to 2 wt% additives of the perovskite oxide La_0.85Yb_0.15AlO₃ (LYA). The structure of dense PEI/LYA films was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) in combination with an analysis of their elemental composition using energy-dispersive spectroscopy (EDS). The PEI/LYA films exhibit a two-layer structure. Contact angle measurements revealed hydrophilization of the membrane surface enriched with the perovskite. The transport properties were tested via gas separation and pervaporation processes. The separation selectivity of He/N₂ and O₂/N₂ gas pairs increased with the growth of the LYA content in the membranes. Pervaporation of a methanol(MeOH)–cyclohexane(CH) mixture was effective due to the high sorption of MeOH in the PEI/LYA membranes. The maximal pervaporation separation index was found for the PEI/LYA(2%) membrane.     

Effect of Pressure on the Aging of Dense (PPO) Membranes

Abstract

The effect of gas pressure on membrane aging was studied thoroughly by applying feed gas pressure continuously or by reducing the feed gas pressure intermittently. Resemblance of aging curves of gas separation membranes to visco‐elastic response curves was observed for all the studied membranes. Membrane aging curves consist of elastic and viscous components. It was further concluded that the elastic component of polymer relaxation was enhanced when membranes were aged at lower pressures while the viscous component was enhanced at higher gas pressures. The transition from the elasticity dominant to the viscosity dominant region occurred more quickly for thicker membranes.     

Effects of Thermal Treatment on Gas Transport Through Porous Silica Membranes

Abstract

The effects of thermal treatment from 180°C to 1150°C on the gas transport properties of porous silica membranes were systematically studied for various gases. The permeance of all gases, except for CO₂, has a maximum at 800°C. The CO₂ permeance was constant from 180°C to 600°C and then decreased monotonically. Membranes thermally treated at 1150°C did not exhibit any gas permeation because of pore collapse. The gas transport behavior follows a combination of Knudsen diffusion and surface diffusion for all gases tested except for carbon dioxide. The permeation of carbon dioxide is strongly affected by capillary condensation. We propose a new transport model composed of two components; that is, the Knudsen diffusion factor, α, and the surface diffusion factor, β. A transition was observed for α and β at around 800–900°C, which is close to the strain point of the membrane. This transition treatment temperature can be correlated with the changes in gas permeance. The model allows qualitative evaluation of gas transport through porous membranes regardless of their actual microporous structures.     

Selective Removal of Carbon Dioxide from Wet CO2/H2 Mixtures via Facilitated Transport Membranes containing Amine Blends as Carriers

The selective separation of carbon dioxide (CO₂) from a wet gaseous mixture of CO₂/H₂ through facilitated transport membranes containing immobilized aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), ethylenediamine (EDA) and monoprotonated ethylenediamine (EDAH⁺) and their blends was experimentally investigated. The effect of CO₂ partial pressure, amine concentration, feed side pressure and amine species on the CO₂ and H₂ permeances were studied. The CO₂ permeability through amine solution membranes decreased with increasing CO₂ feed partial pressure but the H₂ permeance was almost independent of the H₂ partial pressure. A comparison of experimental results showed that single or blended amines with low viscosity and a moderate equilibrium constant, i.e., large forward and reverse reaction rate of CO₂‐amine, are suitable for effective separation of CO₂. The permeability of CO₂ generally increased with an increase in amine concentration, although this increase may be compromised by the salting out effect and decrease in diffusivities of species. The results obtained indicated that CO₂ permeance across a variety of amines are in the order of DEA (2 M) > MD (2 M) > MD (1 M) > MEA (2 M) > MEA (4 M) > MD (4 M) > DEA (1 M) > DEA (4 M) > MEA (1 M) for various concentrations of MEA + DEA blend and are in the order of EDAH⁺ (2 M) > DEA (2 M) > MH (2 M) > DH (2 M) > ED (2 M) > EDA (2 M) > MEA (2 M) for various blends of amine.     

Poly(Vinyl Alcohol)/Graphene Oxide Mixed Matrix Membranes for Pervaporation of Toluene and Isooctane

Poly(vinyl alcohol)/graphene oxide mixed matrix membranes have been prepared and applied for the pervaporation of isooctane (aliphatic) and toluene (aromatic) mixtures. Characteristics of the membranes such as crystallinity, morphology, and swelling have been investigated, and the results have been used to describe pervaporation performance. Experimental tests evidenced that incorporation of low content of graphene oxide nanoplates (0.5?wt%) in poly(vinyl alcohol) increases affinity of the membrane to aromatics by S and π bonds and selectivity increase to about four times. Moreover, interaction of graphene oxide with toluene results in increasing of swelling and decreasing of permeation flux.     

Effect of Silica Nanoparticles on the Performance of Polysulfone Membranes for Olefin‐Paraffin Separation

The separations of ethylene/ethane and propylene/propane using polysulfone‐silica nanocomposite membranes were studied. Silica nanoparticles were prepared via sol‐gel method and the membranes by phase inversion. Characterization by Fourier transform spectroscopy and scanning electron microscopy indicated a good distribution of silica nanoparticles in the polymer matrix and also a good compatibility between the two phases. The performances of the prepared membranes in ethylene‐ethane and propylene‐propane separation were evaluated. The results showed the increments in gas permeability and selectivity by silica. Higher silica contents increased the solubility coefficient and reduced the diffusion coefficient of gases. The plasticization pressure of polysulfone was increased by incorporating the silica nanoparticles in polymer.     

Synthesis and Characterization of ETS-10/Chitosan Nanocomposite Membranes for Pervaporation

Chitosan (CS) and microporous titanosilicate ETS-10/CS mixed matrix membranes (MMMs) were prepared. The pervaporation performance was tested on the water-ethanol mixtures in the range 85–96 wt.% ethanol. The permeate flux increased from 0.45 to 0.55 kg m^?2 h^?1 at 50°C for the ETS-10/CS MMM with respect to the pure CS membranes. Characterization by SEM and TEM, XRD, DSC, and TGA allowed inferring an intimate contact between the dispersed ETS-10 and the continuous chitosan phase. The 5 wt.% loading of titanosilicate scarcely decreased the hydrophilic character of the mixed matrix membrane but increased the molecular sieving effect on the transport and separation properties, thus affecting the membrane behavior on pervaporation.