TiO2/PVA杂化膜的渗透蒸发性能及结构表征

通过纳米TiO2粒子填充改性制备了新型TiO2/PVA杂化膜。红外光谱表明纳米TiO2表面的羟基与聚乙烯醇(PVA)链上的羟基存在较强的氢键作用。扫描电镜显示当TiO2的质量分数低于1.5%时,在PVA中分散均匀。X射线衍射显示纳米TiO2的加入降低了膜的结晶度。通过对含水质量分数低于20%的水/乙醇体系的脱水研究了该杂化膜的渗透性能,考察了TiO2粒子填充量、料液质量分数和温度与膜分离性能之间的关系。渗透通量J随着TiO2、水质量分数和温度的升高而增加,分离因子随着温度和水质量分数的升高而下降,在TiO2质量分数为1.5%时分离因子达到最佳值。40℃下分离质量分数85%的乙醇水溶液,分离因子可达1 590,渗透通量为0.049kg/(m2.h)。     

木粉/TEOS杂化材料制备SiC木材陶瓷的研究

以木粉、正硅酸乙酯(TEOS)为原料,采用溶胶-凝胶方法将TEOS引入到木粉空隙中制备出木粉/TEOS杂化材料,在较低温度下烧结制得SiC木材陶瓷.采用热失重分析(TGA)、X射线衍射分析(XRD)、红外光谱(FT-IR)和扫描电镜(SEM)对其物相变化和显微结构进行了表征,用阿基米德法测定SiC木材陶瓷的显气孔率,研究了烧结温度和杂化材料增重率对SiC木材陶瓷摩擦性能的影响.研究结果表明,木粉/TEOS杂化材料在800 ℃时总的失重率仅为20%,是理想的SiC陶瓷前驱体;杂化材料中的Si-O-C结构可以在1000℃烧结成SiC;SiC木材陶瓷主晶相由β-SiC和SiO2组成,具有类似于木材的多孔拓扑结构;显气孔率随着烧结温度的升高先升后降,而随增重率的增加而增加;耐磨性能随烧结温度和增重率的增加而提高.     

PVA/Nano-SiO_2杂化膜的制备及性能研究

以聚乙烯醇(PVA)和正硅酸乙酯(TEOS)为原料,通过溶胶-凝胶(Sol-Gel)技术,制备出不同nano-SiO2含量的PVA/nano-SiO2杂化膜,并采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)等仪器测试和分析了杂化膜的结构和性能。结果表明:随着nano-SiO2含量的增加,PVA杂化膜的耐水性能增强,结晶能力下降,而力学性能呈现先增大后减小的趋势。当nano-SiO2的加入量在10%左右时,断裂伸长率由纯PVA膜的34.74%提高到55.52%,拉伸强度从33.08 MPa增加到49.98 MPa;而当nano-SiO2含量增加到20%以上时,nanoSiO2粒子会发生团聚,使得杂化膜的力学性能变差。     

新型聚乙烯醇/硅系杂化膜的制备及渗透性能

采用溶胶-凝胶法制备了聚乙烯醇（PVA）/γ-氨丙基三乙氧基硅氧烷（APTEOS）有机/无机杂化膜。用FTIR和XRD对杂化膜进行了表征。测定了膜在乙醇/水溶液中的溶胀行为。考察了杂化膜对85%（质量）的乙醇/水溶液的渗透蒸发分离性能。加入APTEOS降低了PVA的结晶度,有效控制了膜的溶胀,呈现出优良的分离性能。随着APTEOS含量的增加,杂化膜的选择性急剧增加,在5.0%（质量）时达到最大值;同时膜的渗透通量迅速增加。解决了PVA膜trade-off效应。     

催化及杂化正硅酸乙酯防水剂的阻水性能

以正硅酸乙酯(TEOS)为无机前躯体,端羟基硅油(PDMS)为有机杂化剂,在两种催化剂酒石酸(TA)、二月桂酸二丁基锡(DBTL)的作用下,分别制备了TEOS水解-缩合溶胶、TEOS-PDMS杂化水解-缩合溶胶.利用制备的两种溶胶表层浸渍水泥净浆试件,通过测试处理水泥净浆试件的吸水率、接触角评价了两种防水剂的阻水效果;结合红外光谱分析了两种防水剂的形成过程以及作用机理.研究结果表明:表层浸渍处理的水泥净浆试件,其吸水率与水接触角具有良好的相关性;相比于TA,DBTL催化TEOS经水解-缩合形成的防水剂阻水性能更好;PDMS改性TEOS形成的TEOS-PDMS防水剂较杂化前具有更强的阻水性能;防水剂的阻水效果与其凝胶结构中的疏水基团数量密切相关.     

PVA—Zr（IV）催化膜制备及其性能

１引言交联聚乙烯醇（ＰＶＡ）膜用于酯化反应脱水,膜性能随时间发生变化,膜表面红外光谱显示聚乙烯醇上部分ＯＨ被酸酯化了［１］。解决这个问题最好的办法是设计一种膜,既具有催化活性又具有分离功能,反应和分离合二为一。对某物系有催化活性的基团通过化学接枝,...     

GPs-PVA/MCE多功能杂化膜的制备及性能

地聚物微纳米粒子（GPs）经聚乙烯醇（PVA）修饰后,采用真空抽滤法将其组装在混合纤维素基膜（MCE）表面,得到多功能地聚物颗粒-聚乙烯醇/混合纤维素杂化膜（GPs-PVA/MCE）。本文考察了GPs的添加量对杂化膜结构和性能的影响,通过SEM、FTIR、AFM、XRD等表征杂化膜的结构。结果表明GPs添加量为0.15g时制备的杂化膜性能最佳,水通量为11293L/(m²·h·MPa)。该多功能杂化膜对不同污染物均表现出优异的去除性能：通过孔道截留作用可去除水中100%的50nm聚苯乙烯微球和99.87%的乳化油;通过吸附作用亦可去除水中100%的阳离子型染料;比原始MCE膜分别提升了528.54%、25.78%、90.96%。特别是在连续处理含油乳液时,该杂化膜使用1h后通量仅降低了21.70%,远低于MCE膜的95.70%,说明其抗污染性能得到显著提升,显示出良好的应用潜力。     

原位交联聚乙烯醇/二氧化硅杂化功能膜的制备与性能

以正硅酸乙酯（TEOS）为前驱体,戊二醛（GA）为交联剂,利用溶胶凝胶法和原位化学交联法相结合的方法,制备了交联的聚乙烯醇/二氧化硅（PVA/SiO2）杂化功能膜。通过FTIR、SEM、溶胀和拉伸实验研究了二氧化硅和原位化学交联对杂化膜结构和性能的影响。结果表明,制备的膜是具有梯度交联结构的有机/无机杂化体系,原位化学交联对膜断面形貌影响不大。二氧化硅的引入和戊二醛原位交联都能有效地降低杂化膜的平衡溶胀度,两种因素在提高杂化膜耐水性方面具有互补作用。     

Sol-Gel法制备酚醛树脂/SiO2有机-无机杂化材料的研究

采用成熟的Sol-Gel法,以正硅酸乙酯(TEOS)、苯酚、甲醛等为原料,制备酚醛树脂/SiO2杂化材料.探讨了制备工艺过程中的影响因素(反应体系的pH、反应时间、反应温度),并用红外吸收光谱对该杂化材料的结构进行了表征.     

功能化PVI/MOR杂化膜的制备及乙酸脱水分离性能

通过自由基接枝聚合的方法将1-乙烯基咪唑单体接枝到MOR沸石膜的表面,制备出一种新型的亲水性的聚(1-乙烯基咪唑)/丝光沸石(PVI/MOR)杂化膜.并通过扫描电子显微镜(SEM)、X射线衍射(XRD)、傅里叶红外漫反射光谱(DRIFTS)和热重分析等来表征膜的形貌和特性.将膜应用于乙酸脱水分离,考察了不同Ⅵ单体浓度和进料浓度对膜的渗透汽化性能的影响.分析得知以15%的Ⅵ单体浓度制备的PVI/MOR杂化膜具有最好的分离性能,在80℃下和71%～94%的进料浓度范围内均达到理想选择性分离,也就是说在透过侧产品水的含量达到100%.这些实验结果表明将PVI基团接枝到MOR沸石膜层能实现真正意义上的功能化修补膜的缺陷和大大提高膜的分离性能的目的.     

Pervaporation characteristics and structure of poly(vinyl alcohol)/poly(ethylene glycol)/tetraethoxysilane hybrid membranes

Poly(vinyl alcohol) (PVA) blended with poly(ethylene glycol) (PEG) was crosslinked with tetraethoxysilane (TEOS) to prepare organic–inorganic PVA/PEG/TEOS hybrid membranes. The membranes were then used for the dehydration of ethanol by pervaporation (PV). The physicochemical structure of the hybrid membranes was studied with Fourier transform infrared spectra (FT‐IR), wide‐angle X‐ray diffraction WXRD, and scanning electron microscopy (SEM). PVA and PEG were crosslinked with TEOS, and the crosslinking density increased with increases in the TEOS content, annealing temperature, and time. The water permselectivity of the hybrid membranes increased with increasing annealing temperature or time; however, the permeation fluxes decreased at the same time. SEM pictures showed that phase separation took place in the hybrid membranes when the TEOS content was greater than 15 wt %. The water permselectivity increased with the addition of TEOS and reached the maximum at 10 wt % TEOS. The water permselectivity decreased, whereas the permeation flux increased, with an increase in the feed water content or feed temperature. The hybrid membrane that was annealed at 130°C for 12 h exhibited high permselectivity with a separation factor of 300 and a permeation flux of 0.046 kg m^?2 h^?1 in PV of 15 wt % water in ethanol. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Separation characteristics of pervaporation membrane separation processes using modified poly(vinyl alcohol) membranes

Modified poly(vinyl alcohol) (PVA) membranes prepared by the ‘solution technique’ were tested for ethanol-water mixtures by varying the reaction density (X_cr = 0.05, 0.1) at various temperatures. The results are compared with those of PVA membranes (X_cr = 0.05) prepared by the technique of the GFT Company, Germany.     

石墨填充聚乙烯醇膜渗透蒸发分离苯和环己烷

采用液相共混法制备了石墨填充聚乙烯醇膜,采用FTIR,SEM,XRD等对石墨填充聚乙烯醇膜的物理和化学结构进行了分析表征,结果表明石墨与聚乙烯醇存在较强的氢键作用,石墨在聚乙烯醇中分散均匀,且具有一定的取向性.考察了石墨填充聚乙烯醇膜在苯和环己烷溶液中的溶胀和吸附行为.采用正电子湮没寿命谱仪表征了石墨聚乙烯醇膜的自由体积特性,计算得到石墨聚乙烯醇膜的表观自由体积分数,并且与渗透通量进行关联性对比.最后,研究了石墨含量和粒径对渗透蒸发分离性能的影响,结果表明,石墨的引入有利于苯的优先透过,石墨填充聚乙烯醇膜对苯和环己烷混合物具有良好的分离效果,苯的渗透通量和分离因子分别可达90.7 g•m^-2•h^-1和100.1.     

Preparation of PFSA‐PVA/PSf hollow fiber membrane for IPA/H2O pervaporation process

Using Na⁺ form of perfluorosulfonic acid (PFSA) and poly(vinyl alcohol) (PVA) as coating materials, polysulfone (PSf) hollow fiber ultrafiltration membrane as a substrate membrane, PFSA‐PVA/PSf hollow fiber composite membrane was fabricated by dip‐coating method. The membranes were post‐treated by two methods of heat treatment and by both heat treatment and chemical crosslinking. Maleic anhydride (MAC) aqueous solution was used as chemical crosslinking agent using 0.5 wt % H₂SO₄ as a catalyst. PFSA‐PVA/PSf hollow fiber composite membranes were used for the pervaporation (PV) separation of isopropanol (IPA)/H₂O mixture. Based on the experimental results, PFSA‐PVA/PSf hollow fiber composite membrane is suitable for the PV dehydration of IPA/H₂O solution. With the increment of heat treatment temperature, the separation factor increased and the total permeation flux decreased. The addition of PVA in PFSA‐PVA coating solution was favorable for the improvement of the separation factor of the composite membranes post‐treated by heat treatment. Compared with the membranes by heat treatment, the separation factors of the composite membranes post‐treated by both heat treatment and chemical crosslinking were evidently improved and reached to be about 520 for 95/5 IPA/water. The membranes post‐treated by heat had some cracks which disappeared after chemical crosslinking for a proper time. Effects of feed temperature on PV performance had some differences for the membranes with different composition of coating layer. The composite membranes with the higher mass fraction of PVA in PFSA‐PVA coating solution were more sensitive to temperature. It was concluded that the proper preparation conditions for the composite membranes were as follows: firstly, heated at 160°C for 1 h, then chemical crosslinking at 40°C for 3 h in 4% MAC aqueous solution. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

季铵化聚乙烯醇/聚二甲基二烯丙基氯化铵/正硅酸乙酯杂化阴离子交换膜的制备与性能表征

通过在季铵化聚乙烯醇(QPVA)和聚二甲基二烯丙基氯化铵(PDADMAC)混合聚合物水溶液中添加正硅酸乙酯(TEOS)进行溶胶-凝胶反应,制备得到了不同配比的溶胶-凝胶铸膜液,并将各铸膜液在模具中干燥得到杂化膜,随后将杂化膜在戊二醛/丙酮溶液中交联得到尺寸稳定的杂化阴离子交换膜。考察了季铵化聚乙烯醇和聚二甲基二烯丙基氯化铵铸膜液的质量比对杂化膜稳定性的影响。主要分析了4种尺寸稳定阴离子交换膜的外观形貌、红外光谱、微观形貌、热稳定性、含水/甲醇率和膜的离子交换容量。结果表明,QPVA/0.25PDADMAC/0.1TEOS碱性杂化膜在甲醇中尺寸稳定,微观结构致密,在65～140℃时热稳定性优良,离子交换容量可达到1.091 41 mmol/g。具有在中低温型碱性直接甲醇燃料电池中使用的潜力。     

聚二甲基硅氧烷膜中乙醇-水的吸附和渗透蒸发行为

以乙醇/水体系为研究对象,结合F lory-Huggins理论,讨论溶胀过程的热力学行为,用以分析和考察聚二甲基硅氧烷(PDMS)膜在乙醇/水中的溶胀特性及组分间的耦合效应。结果表明,在乙醇质量分数20%—40%,膜的溶胀程度最大。渗透蒸发实验表明,水的渗透速率在乙醇质量分数不大于30%范围内变化很小,而乙醇的渗透速率基本随溶液中乙醇质量分数增加而增大。     

Poly(vinyl alcohol) and poly(vinyl amine) blend membranes for isopropanol dehydration

Blended membranes of hydrophilic polymers poly(vinyl alcohol) (PVA) and poly(vinyl amine) (PVAm) were prepared and crosslinked with glutaraldehyde. The prepared membranes were characterized using infrared (attenuated total reflection mode) spectroscopy, differential scanning calorimetry, X‐ray diffractometry, and scanning electron microscopy measurements. Pervaporation performances of the membranes were evaluated for the separation of water‐isopropanol (IPA) mixtures. As the PVAm content increased from PVAm0 to PVAm1.5, the flux through a 70 μm film increased from 0.023 to 0.10 kg/m² h at an IPA/water feed ratio of 85/15 at 30 °C. The driving force for permeation of water increased due to the temperature but it has no effect on IPA permeation. Activation energies for the permeation of IPA and water were calculated to be 17.11 and 12.46 kJ/mol, respectively. Controlling the thickness of the blend membrane could improve the permeation flux with only a marginal reduction in the separation factor. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45572.     

Pervaporation dehydration of water/ethanol/ethyl acetate mixtures using poly(vinyl alcohol)–silica hybrid membranes

The novel organic–inorganic hybrid membranes were prepared from poly(vinyl alcohol) (PVA) and vinyltriethoxysilane (VTES). They were characterized using Fourier transform infrared (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA), and contact angle metering. The as‐prepared membranes are formed at a molecular scale at a low VTES content. Aggregations in the surface of the as‐prepared membranes were clearly evident above 18.43 wt % VTES loading. The introduction of VTES into the PVA matrix resulted in a decrease in the crystalline and an increase in compactness and thermal stability of the as‐prepared membranes. Silica hybridization reduced the swelling of the as‐prepared membranes in water/ethanol/ethyl acetate mixtures, decreased the permeation flux, and remarkably enhanced water permselectivity in pervaporation dehydration of ethanol/ethyl acetate aqueous solution. The hybrid membrane with 24.04 wt % VTES has the highest separation factor of 1079 and permeation flux of 540 g m^?2 h^?1. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012