相转化法制备氧化钇稳定氧化锆中空纤维陶瓷膜

采用相转化和烧结相结合的方法制备了氧化钇稳定氧化锆(YSZ)中空纤维陶瓷膜，研究了铸膜液中YSZ粉末含量和烧结温度对中空纤维陶瓷膜的微观结构和性能的影响。结果表明，YSZ中空纤维陶瓷膜的不对称结构包含指状结构和海绵状结构，YSZ含量会影响两种结构的比例，烧结则会引起微观结构的致密化。在铸膜液配比为m(YSZ):m(PSF):m(NMP)=5.0:1:4，烧结温度为1200 ℃的条件下制备出性能良好的中空纤维陶瓷膜，其纯水通量为2.33 m3/(m2·h·MPa)，抗弯强度为134.5 MPa。     

高渗透性YSZ中空纤维陶瓷微滤膜的制备

采用相转化和高温烧结相结合的方法,并在纺丝过程分别以水和乙醇作为芯液和外凝固浴制备了多孔氧化钇稳定氧化锆（YSZ）中空纤维陶瓷膜,对制备的中空纤维膜微观结构、孔径分布和孔隙率、纯水通量和氮气渗透性等进行了表征。结果表明：制备的YSZ中空纤维膜为多孔非对称结构,由外部薄的海绵状多孔皮层和内部大的指孔层构成。在1350℃保温4h烧成制备的YSZ中空纤维膜表现出高渗透性,在0.10MPa压差下的纯水和氮气渗透性分别达到43.0m^3/（m^2·h.MPa）和8345.7m^3/（m^2·h·MPa）。     

聚醚砜分子量对相转化法YSZ中空纤维陶瓷膜结构与性能的影响

采用不同分子量聚醚砜(PES)作为聚合物结合剂,通过相转化法和高温烧结制备了非对称结构YSZ中空纤维陶瓷膜。研究了不同分子量聚醚砜制备的铸膜浆料粘度变化对相转化过程及膜的微观结构与孔隙率和孔径、纯水和氮气渗透通量及抗弯强度等性能的影响。结果表明,采用分子量较小的PES制备的中空纤维膜由内侧大指孔结构和外侧小指孔结构构成。随着PES分子量和铸膜浆料粘度提高,外侧指孔长大而内侧指孔减小,且出现明显的中间海绵层。随着浆料粘度提高,膜孔隙率明显下降。采用PES E3010作为聚合物原料时,制备的YSZ中空纤维膜具有最大的外表皮层分离孔径,表现出最高的渗透性能和抗弯强度,在1400℃保温3 h烧结时,膜纯水通量和抗弯强度分别可达到9.35 m~3/(m~2·h·MPa)和113.9 MPa。     

多孔堇青石中空纤维陶瓷膜的制备与表征(英文)

采用相转化和烧结法,通过一步成型制备了新颖的堇青石中空纤维陶瓷膜,并对制备的中空纤维膜微观结构、孔隙率和孔径分布、抗弯强度、纯净水通量和氮气渗透性等结构与性能进行了表征。结果表明:堇青石中空纤维膜为多孔非对称结构,由内部大孔层和外部海绵状多孔层组成。在1360℃保温2h制备的堇青石中空纤维膜孔隙率为39.2%,抗弯强度为76.5MPa。0.10MPa压差下的纯净水和氮气渗透性分别达到61.34m3/(m2·h·MPa)和7824m3/(m2·h·MPa)。实验证明,采用较大粒径的廉价工业级粉体为原料,可制备非对称的中空纤维陶瓷微滤膜。     

刚玉基陶瓷膜的制备与性能研究

为了解原料粒径对刚玉基陶瓷膜形貌和性能的影响,分别以10μm和20μm的近等径刚玉为陶瓷膜原料,以硅溶胶为结合剂,六偏磷酸钠为分散剂,羧甲基纤维素为增稠剂,采用浸浆法在自制多孔SiC支撑体(平均孔径97. 2μm)表面涂覆刚玉基陶瓷膜,观察了膜的表面形貌、孔隙结构,并测试了膜的孔隙尺寸及分布、渗透性及阻力降。结果表明:当SiC支撑体孔径与刚玉颗粒的粒径之比5时,制成的陶瓷膜表面平整;而当二者之比10时,膜的表面出现明显凹坑。使用20μm刚玉颗粒制备的刚玉陶瓷膜,其常温抗折强度为27. 6 MPa,阻力降为426. 6 Pa,气体渗透率为143. 3 m~3·(m~2·h·kPa)~(-1),具有较好的综合性能,可满足烟气净化的技术要求。     

多孔PZT压电陶瓷膜的制备及其抗污染性能

以PbZr_xTi_(1-x)O_3(PZT)压电陶瓷粉体为原料,通过干压成型的方法制备多孔PZT陶瓷膜,考察了煅烧温度对多孔PZT陶瓷膜的机械强度、孔隙率以及纯水渗透性能的影响。当煅烧温度为950℃时,可制备出纯水渗透率为850 L·m~(-2)·h~(-1)·MPa~(-1),孔径为300 nm,机械强度为47.8 MPa,孔隙率为34%的多孔PZT陶瓷膜。在此基础上,考察了极化温度与极化电压对多孔PZT陶瓷膜压电性能的影响,并对极化后的PZT压电陶瓷膜进行萃取和表面等离子刻蚀处理。结果表明:极化温度为120℃、极化电压强度为4 k V·mm~(-1),极化后经热乙醇萃取及表面等离子刻蚀4 min后,多孔PZT压电陶瓷膜在外加交流电为20 V时,产生的共振振幅信号值达34.8 m V。将制备的多孔PZT压电陶瓷膜在粒径为600 nm的含油乳化液中进行过滤实验,发现陶瓷膜两端未加交流电时,其通量在2 h内衰减至4%。而加交流电后,其稳定通量可维持在20%左右,表明制备的多孔PZT压电陶瓷膜具有良好的抗污染效果。     

非对称LSCF中空纤维透氧膜的制备及性能

采用溶胶-凝胶法制备了具有钙钛矿型结构的La_(0.6)Sr_(0.4)Co_(1-y)Fe_yO_(3-δ)(LSCF,y=0.2,0.5或0.8)氧化物,然后以相转化烧结技术制备了LSCF中空纤维透氧膜,考察了凝固浴与Co/Fe摩尔比对LSCF中空纤维膜微结构及透氧性能的影响。使用70%(质量分数) NMP与30%乙醇的混合液作为内凝固浴,去离子水为外凝固浴,制备了具有外表面薄而致密的分离层、同时具有贯穿内表面的众多指状孔结构的LSCF中空纤维陶瓷膜。指状孔结构会极大地降低扩散阻力,从而改善LSCF膜的透氧量。LSCF中空纤维膜的透氧量随温度和吹扫气He吹扫速率的增加逐渐升高。Co/Fe摩尔比对LSCF中空纤维膜的微观结构和透氧量具有重要影响,透氧量随Co/Fe摩尔比的增大而增加。950℃(透氧膜的测试温度)、吹扫气He的吹扫速率为120 m L·min~(-1)、Co/Fe摩尔比为4时,LSCF透氧膜的氧气渗透通量达到2.81 m L·min~(-1)·cm~(-2)。     

湿法纺丝工艺制备Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3–δ)中空纤维陶瓷透氧膜及其改性研究

采用固相反应法合成Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3–δ)(BSCF)粉,并以其为原料,采用湿法纺丝工艺及烧结处理制备出外径为3 mm、壁厚为400μm的BSCF中空纤维膜,通过涂覆法,在中空纤维膜的外表面负载BSCF多孔层,以进一步改善其透氧性能。利用X射线衍射对BSCF粉末与中空纤维膜的相组成进行分析,采用扫描电子显微镜对中空纤维膜的微观组织进行观测,对修饰后BSCF膜的透氧性能进行测试。结果表明:采用固相反应法可制备出具有单一钙钛矿相的BSCF粉体,湿法纺丝所制备的BSCF中空纤维膜具有非对称结构;在空气/真空梯度下,未经表面修饰的BSCF膜在700和900℃时的透氧速率分别为0.382和1.284 m L/(cm2·min)。表面负载Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3–δ)多孔层后,其700和900℃的透氧速率分别增加到1.250和2.426 m L/(cm2·min)。表面负载使BSCF的中空纤维透氧膜的透氧表观活化能从49.23降低至24.74 k J/mol。     

氧化铝添加量对多孔碳化硅支撑体性能的影响

以平均粒径为27.6μm的α-Si C为骨料、亚微米碳化硅和α-Al2O3为助烧剂,采用干压成型法在空气氛围中烧成制备多孔碳化硅支撑体,研究了氧化铝含量对多孔碳化硅支撑体结构及性能的影响。结果表明:当氧化铝添加量为10%(质量分数)、烧成温度为1 450℃时,支撑体的孔径、孔隙率、抗弯强度和纯水通量分别为0.3μm、31.8%、39.1 MPa和786 L·m~(–2)·h~(–1)·bar~(–1)。经过80℃,10%的Na OH溶液中腐蚀4 h后,多孔碳化硅支撑体的抗弯强度仍高于18 MPa。     

对流-扩散法制备多孔衬底支撑梯度结构电解质薄膜

以多孔氧化铝(porous alumina,p-Al2O3)为模型多孔电极衬底材料,利用对流-扩散效应成功制备得到了具有梯度结构的8%(以摩尔计)钇稳定氧化锆(yttria-stabilized zirconia,YSZ)电解质薄膜.该方法新颖、经济简单、适合于制备大尺寸平板型固体氧化物燃料电池中多孔电极支撑的电解质薄膜.利用扫描电镜和X射线角散分析技术对所制备电解质薄膜/p-Al2O3样品进行了微结构测试和表征.结果表明:由该方法在多孔衬底上实现的YSZ电解质薄膜由生长于衬底表面上的均匀致密层(≈10μm)和衬底表面下孔道中均匀填充层(≈50μm)与弥散填充层(≈250μm)构成,且各层厚度可通过改变对流-扩散沉积条件得到调节.     

Yttria Stabilized Zirconia Hollow Fiber Membranes

Yttria-stabilized zirconia (YSZ) hollow fiber membranes have been developed by a combined phase inversion and sintering method. An organic binder solution (dope) containing suspended YSZ particles is spun to form a hollow fiber precursor, which is then sintered at elevated temperatures. The prepared hollow fibers have the asymmetric structure including the sponge-like structures at center, sandwiched by the long finger-like structures located at the outer and inner walls of the fibers. Experimental results indicate that by controlling the YSZ/polymer weight ratio at 9 or 10 and sintered at a temperature of 1590°C or 1550°C for 10 h, respectively, gas-tight asymmetric YSZ hollow fiber membranes with high mechanical strength can be obtained.     

Preparation and membrane performance of poly(ethylene-co-vinyl alcohol) hollow fiber membrane via thermally induced phase separation

Poly(ethylene-co-vinyl alcohol) (EVOH) hollow fiber membranes with ultrafiltration performance were prepared from EVOH/glycerol systems via thermally induced phase separation (TIPS). The diluent glycerol was used as bore liquid to make a lumen of the hollow fiber for the purpose of prevention of the diluent evaporation and the larger pores formation at the inner surface of the hollow fiber. The obtained hollow fiber membranes showed asymmetric structures with skin layer near the outer surface, the larger pores just below the skin layer and the smaller pores near the inner surface. The formation of the larger pores near the outer surface was due to the enhanced pore growth by the water penetration. Some primary factors affecting the structure and performance of the membranes such as ethylene content (EC) in EVOH, cooling water bath temperature and take-up speed were studied extensively. The water permeability can be improved by increasing the water bath temperature and the take-up speed and by decreasing the EC. Both the pore size at the outer surface and the connectivity between the pores have to be considered together to understand the experimental result of the water permeability and the solute rejection.     

PDMS涂覆的Al2O3中空纤维膜在ABE/水体系分离中的应用

通过浸渍-提拉的方法制备了PDMS涂覆的Al2O3中空纤维膜,并系统地研究了其用于ABE/水体系的分离过程。首先对制备出的膜进行了形貌表征,SEM电镜照片表明,所用的Al2O3中空纤维支撑体具有非对称结构,海绵孔位于膜壁的中间而指状孔在其两侧。制备出的PDMS涂覆的Al2O3中空纤维复合膜表面致密完好没有缺陷,其厚度小于10μm,说明PDMS层被均匀地涂在支撑体外表面。然后在不同的模拟体系(丙酮-水、丁醇-水、乙醇-水)中,系统地考察了复合膜的性能。实验表明,复合膜具有优异的渗透汽化性能(通量和分离因子)。最后将该复合膜用于ABE-水体系的分离,考察了膜在操作过程中的渗透汽化性能和稳定性,同时将二元体系与四元体系过程对比,讨论渗透汽化对ABE体系的分离作用。     

Microporous polypropylene hollow fibers with double layers

Microporous polypropylene hollow fibers with double layers were prepared by stretching double layered polypropylene microtubes containing polymethylsilsesquioxane fillers: the relatively smaller filler in the inner layer and relatively larger filler in the outer layer. The resultant hollow fibers have a finely interconnected fibrous structure parallel to fiber axis. Their N₂ gas permeabilities were measured to estimate the fibrous structure: tortuosity factor, effective porosity, and pore size. © 1995 John Wiley & Sons, Inc.     

Fundamental study of the effect of the fiber wall thickness and inner diameter on the structure of polyamide and polypropylene hollow fibers

Some properties of the structure of polyamide (PA) and polypropylene (PP) hollow fibers were investigated in a theoretical fashion. These fibers were simultaneously compared with solid fibers. The structural indices of the hollow fibers, that is, the wall thickness and inner diameter, were systematically examined with the aim of determining their effect on the four conventional structural indices suitable for hollow fibers and for solid fibers. The fiber outer diameter and fiber outer lateral area were examined as well, and the ratio of the fiber outer lateral area to the fiber whole volume and the ratio of this area to the fiber mass were considered. Under assumptions about the fixed level and equal values of the linear density of PA and PP fibers, comments on the aforementioned effect were presented. The structural properties of these fibers with different wall thicknesses and inner diameters were examined. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2017–2022, 2004     

镍基非对称中空纤维膜用于乙醇自热重整制氢

采用纺丝-烧结技术制备了具有内表面致密皮层的外支撑式金属镍非对称中空纤维膜,并用于乙醇自热重整（EATR）制氢,研究了温度、进料流速、吹扫气流速、水醇比（S/C）以及氧醇比（O₂/C）等操作条件对膜制氢性能的影响。结果表明,金属镍非对称中空纤维膜既具有优异的EATR催化活性,又有良好的透氢性能。在500～1000℃、S/C=4、O₂/C=0.8的条件下乙醇可完全转化,H₂产率和H₂渗透通量可分别达到81.59%和13.99 mmol/（m²·s）,增加进料中氧气含量可显著抑制膜表面积炭,但同时也会降低氢气产率和一氧化碳选择性。     

Effect of the preparation conditions on the morphology and performance of poly(imide) hollow fiber membranes

Poly(imide) (PI) hollow fiber membranes were prepared by using classical phase inversion process. Effects of different external coagulation bath temperatures (ECBT) and various bore flow rates (BFR) on the morphology and separation performance of the membranes were studied. Cross‐section, inner and outer structures were characterized by using scanning electron microscope and atomic force microscopy (AFM). Mean pore size, pore size distribution, and mean roughness of the PI hollow fibers surfaces were estimated by AFM. It was found that the hollow fibers morphology composed of sponge‐like and finger‐like structures with different ECBT and BFR. A circular shape of the nodules with different sizes was observed in the outer surface of the PI hollow fibers. Mean pore size of the outer surface increases with increasing ECBT and BFR. The important result observed in this study is that the ECBT clearly has the largest effect on hollow fiber PI membrane roughness compared with the BFR. Pure water permeability of the PI hollow fibers was improved with increase of ECBT and BFR. The solute rejection (R%) was reduced when the ECBT and BFR was increased. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40428.     

Fabrication of polysulfone asymmetric hollow‐fiber membranes by coextrusion through a triple‐orifice spinneret

Polysulfone (PSf) asymmetric hollow‐fiber membranes, which have a dense outer layer but a loose inner layer, were tentatively fabricated by coextrusion through a triple‐orifice spinneret and a dry/wet‐phase inversion process. Two simple polymer dopes were tailored, respectively, for the dense outer layer and the porous inner layer according to the principles of the phase‐inversion process. By adjusting the ratio of the inner/outer extrusion rate, the hollow‐fiber membranes with various thicknesses of outer layers were achieved. The morphology of the hollow‐fiber membranes was exhibited and the processing conditions and the water permeability of the membrane were investigated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 259–266, 2004     

Large-scale synthesis of hollow carbon fibers with ultra-large diameter by thermally controlled pyrolysis

Hollow carbon fibers (HCF) with ultra-large diameter have been synthesized and the versatility to convert them into the corresponding carbon-based composites has been demonstrated. The hollow carbon fibers were fabricated by thermal controlled carbonization of electrospun polyacrylonitrile fibers. For the existence of inorganic silica shell during pyrolysis, heat release will be blocked at the boundary, driving the polyacrylonitrile precursor fiber to form hollow structure. The diameter of the as-prepared hollow carbon fibers can exceed 150 nm. Sol-gel-derived Fe₃O₄ nanoparticles can grow on the outer-surface and the inner-surface of hollow carbon fibers. The microwave absorption performance of ternary HCF@Fe₃O₄@PPy composite is testified and the values of reflection loss exceeding −10 dB can be obtained in the frequency of 3.3-11.3 GHz. The large diameter of hollow carbon fibers can have inner and outer interfaces in the corresponding composites, which make them great potential for a variety of applications in future.