1、第四讲：分离膜材料表征方法第四讲：分离膜材料表征方法制膜制膜结构评价结构评价面向对象面向对象MFUFNFROPV 分离膜表征的目标和内容分离膜表征的目标和内容膜结构评价内容膜结构评价内容 1）几何结构：孔径、孔径分布、孔隙率、孔形状）几何结构：孔径、孔径分布、孔隙率、孔形状2）化学构造：）化学构造： 表面能、接触角、吸附特性等表面能、接触角、吸附特性等3）孔结构的模型化方法）孔结构的模型化方法4) 膜分离性能的表征膜分离性能的表征4.14.1多孔膜的表征多孔膜的表征4.4.2 2 致密膜的表征致密膜的表征4.4.3 3 离子交换膜的表征离子交换膜的表征膜表征技术的分类膜表征技术的分类PTFE
2、membranesDefinition of pore size（ IUPAC） Macropores pore size 50nm mesopores 2nm pore size 50nm Micropores pore size 2nm Microfiltration membrane (macropores)Ultrafiltration membrane (mesopores in top layer)0.110m110nmSchematic drawing of a porous and a nonporous membrane Structure-related parameter
3、 Pore size Pore size distribution Top layer thickness and surface porosity Permeation-related parameter Cut-off measurementThe permeation parameters are difficult to related directly to the structure parameters because the pore size and shape is not very well defined.Characterization of porous membr
4、anesIdeal and actual structure in the top layer of ultrafiltration membraneCharacterization techniques for microfiltration membraneswScanning electron microscopywBubble-point methodwMercury intrusion porometryPermeation measurements1.Morphological or structure parameter2.Permeation parameterElectron
5、 microscopy(EM)SEMThe principle of scanning electron microscopy (SEM).1-25kVCoating with a gold layer to avoid sample be burned or damaged电子显微镜电子显微镜(SEM, TEM)(SEM, TEM)观察方法观察方法 分离膜特性表征分离膜特性表征 基本原理基本原理 Laplace 方程方程 Kelvin 方程方程 基本方法基本方法 4.1.1)电子显微镜电子显微镜(SEM, TEM)观察观察 作业：推导反映毛细管作用的作业：推导反映毛细管作用的 Kelvin
6、Kelvin 方程。方程。 例题：计算孔径例题：计算孔径 0.2um0.2um，孔数孔数10109 9个个/cm/cm2 2微孔膜表面微孔膜表面孔隙率？孔隙率？解：孔面积（解：孔面积（/4)/4)(0.2(0.21010- -4 4) )2 210109 9=0.314cm=0.314cm2 2 孔隙率孔隙率=31.4%=31.4%Atomic force microscopy(AFM)Advantage: noparameter is required and the measurement can be carried out under atomospheric conditionsDi
7、sadvantage: high surface roughness may result in images which are difficult to interpretedDisadvantage: high forces may damage the polymeric structure 1 nN forces原子力显微镜原子力显微镜(AFM)(AFM)观察方法观察方法AFMAFM analysis of PSf(10 wt%)/NMP/ H2O membrane, casting at 70 .AFMAFM analysis of PSf(10 wt%)/NMP+ 15 wt%
8、Span-80/ H2O membrane, casting at 70 .膜膜水水压缩空气4.1.2 泡点法泡点法Bubble-point method（泡点法）泡点法）The principle of the bubble-point methodcos2Prprbubble rpore cos1Prp2rp：radius of a capillary shaped pore：surface tension at the liquid/air interfaceP：pressure difference【例題】泡点【例題】泡点P=1.4 MPa时，已知水的表面张力时，已知水的表面张力=0.
9、072 N/m, 接触角接触角cos=1 求最大膜孔径？求最大膜孔径？ 解：解： d=40.0711/1.4106 = 2.0510-7 m= 0.206 m Permeability method (if capillary pores are present)Wetting pressure for water as a function of the pore diameter for porous polypropylene (Accrual).Pressure needed to wet the PP membrane4.1.3 Permeability method（渗透测孔法）渗
10、透测孔法）Flux versus pressure curve for a membrane possessing a uniform pore size.Permeability method（渗透测孔法）渗透测孔法）Flux versus pressure curve for a membrane exhibiting a pore size distribution.4.1.4 超滤膜截留分子量的确定超滤膜截留分子量的确定 超滤膜超滤膜 完全截留完全截留 部分截留部分截留 完全渗透完全渗透90 Cf CpfpCCfC R截留率membraneCpermeateCfeedCpermeate
11、CRMiMiMiMiMi11RMi：the fractional rejection（ 截留率截留率）CMi(permeate)：the concentration of the permeateCMi(feed) ：the concentration of the feedCMi(membrane)：the concentration at the membrane surfaceSolute rejection measurements（溶质截留测定）（溶质截留测定） T-1 T-2V-1V-4V-3V-2V-5PPIC10-TC111跨膜压强差时间有效膜面积渗透量渗透通量 FluxPer
12、meability methodsDSC/DTA methodsTGA analysis methodDensity gradient columnsWide-angle X-ray diffraction (WAXS)FTIR analysis methodPlasma etchingSurface analysis methodsMechanical properties analysis4.4.2 2 致密膜的表征致密膜的表征4.2.1 Permeability methodsGas permeability apparatus.Permeability methodsLiquid pe
13、rmeability (pervaporation) apparatus.Pervaporation instrumentFTIR analysis methodFT-IR spectra of poly(imide siloxane)/silica hybrids.Silica content：(a) 10 wt%(b) 30 wt%(c) 50 wt%1778、1720 cm-1C=O1382 cm-1CNC1080 cm-1SiOSi720 cm-1C6H4 or SiOSi4.2.2 4.2.2 常用的仪器分析方法常用的仪器分析方法FTIR analysis methodFTIRATR
14、 spectra of 6FDA6FpDADABA-25 22.5 wt.% MTMOS hybrid material. Shading highlights areas of change after the annealing process.Wide-angle X-ray diffraction (WAXS)Schematicdrawing of the WAXS technique.Wide-angle X-ray diffraction (WAXS)A typical plot of scattering intensity versus diffraction angle ob
15、tained from wide-angle X-ray diffractionWide-angle X-ray diffraction (WAXS)5101520253035404550(a)(b)(c)WAXD scan of TMBPS-based polyimide membranes 2intensityPolyimide membranes：(a) TMBPS-BTDA(b) TMBPS-ODPA(c) TMBPS-6FDA e+Pspolymer chainssize distributionmean hole volumeDistributions of o-Ps lifeti
16、me and free-volume for polystyreneLiu J, Deng Q, Jean Y C. Macromolecules, 1993, 26, 7149. deequivalent diameterde13210.5ns 1sin2hhhhrrrrrr343hhvr The physics of matter-antimatter annihilation allows to extract nanoscale materials information specific to the location at which the annihilation takes
17、place. Suitable for probing the sub-nanometer voids in bulk polymers A good calibration in the diameter range from 0.3 to 30 nmA low energy poistron beam(0.1-10keV) provides a non-destructive and non-intrusive porosimetry. 导电性导电性 稳定性稳定性（抗氧化性、机械强度、热稳定性）（抗氧化性、机械强度、热稳定性） 使用性能（使用性能（电池实验）电池实验） （阻钒性能、库伦效率、能量效率） 4.4.3 3 离子交换膜的表征离子交换膜的表征 掌握基本手段和方法，满足实际研究掌握基本手段和方法，满足实际研究与生产目的需求，创新和探索准确、快捷、与生产目的需求，创新和探索准确、快捷、便宜的膜材料表征技术。便宜的膜材料表征技术。膜表征的原则膜表征的原则
