Abstract:

Polyvinylpyrrolidon （PVP）-P84 copolyimide（P84） / polyacrylonitrile（PAN） composite membranes were prepared via blending of PVP into P84 matrix. Membranes were characterized by Fourier transform infrared（FTIR），X-ray diffraction（XRD），scanning electron microscopy（SEM），differential scanning calorimeter（DSC） and contact angle（CA） metering. FTIR analysis indicated that PVP and P84 were physically blended. DSC results showed that the P84-PVP blends possessed a single glass-transition temperature， indicating a good miscibility of blend. The contact angle test demonstrated that the hydrophility of membranes was improved with the incorporation of PVP. XRD results indicated that d-spacing in the P84-PVP blend was increased when the PVP loading amount was increased. The effect of PVP loading，operating temperature and feed composition on the pervaporation performance of the composite membranes was examined. When PVP content was enhanced to 20%， the total permeation flux was increased. Meanwhile，the separation factor was first increased with the PVP content≤ 10%，and then decreased quickly. The composite membrane with a PVP loading amount of 10% exhibited the best performance with a total flux of 259g/(m²?h) and a separation factor of 41 using a feed of methanol（30%）/tetrahydrofuran at 20℃.

Key words: co-polyimide, polyvinylpyrrolidone, blend membrane, pervaporation

摘要：

通过聚乙烯吡咯烷酮（PVP）与P84共聚聚酰亚胺（P84）共混，以聚丙烯腈（PAN）超滤膜为支撑层，制备了不同PVP含量的P84-PVP/PAN复合膜。采用傅里叶红外光谱（FTIR）、X射线衍射（XRD）、扫描电镜（SEM）、差示扫描量热仪（DSC）和接触角（CA）测量等方法对复合膜进行表征。FTIR分析表明，PVP与P84为物理共混。DSC结果显示共混物存在单一玻璃化转变温度，具有良好相容性。此外，水接触角测试显示PVP引入提高了膜亲水性。XRD结果表明，随着PVP含量的增加，共混物分子链平均间距增大，膜内自由体积增大。考察了PVP含量、操作温度及料液浓度对渗透汽化分离甲醇/四氢呋喃性能的影响。结果表明，随着共混物中PVP质量分数增加至20%，膜渗透通量逐渐增大，分离因子先增加（PVP质量分数≤ 10%）而后迅速降低。当PVP质量分数为10%、进料温度为20℃时，复合膜对于质量分数30%甲醇/四氢呋喃有最优的分离性能，其渗透通量为259g/(m²?h)，分离因子为41。

关键词: 聚酰亚胺, 聚乙烯吡咯烷酮, 共混膜, 渗透汽化