【作者】 乔宁宁；

【导师】 张卫东；

【作者基本信息】 北京化工大学 ， 化学工程， 2009， 硕士

【摘要】 聚偏氟乙烯膜(PVDF)是一种性能优良的高分子聚合物分离膜。但是,在PVDF膜的应用过程中,由于其强疏水性和易污染性,限制了其在水基体系,尤其是处理蛋白质溶液时的应用。因而,需要对PVDF膜进行改性研究来拓宽其应用领域。本课题通过共混的方法,制备PVDF/PS/PMMA三元共混膜,不仅对PVDF膜的强疏水性进行改善,而且进一步改善了其污染性。采用浸没沉淀法制备了PVDF膜,考察了PVDF浓度、添加剂浓度、溶剂和凝固浴温度等条件对PVDF膜结构和性能的影响。在PVDF浓度为14wt%时制备的PVDF结构最佳;添加剂浓度为4wt%～6wt%时能起到比较充分的致孔作用;DMF和DMAc分别作为溶剂对于制备PVDF膜的结构和性能基本没有区别;凝固浴温度为20℃时制备的PVDF膜结构最佳。选择了膜材料加入亲水性物质聚甲基丙烯酸甲酯(PMMA)改善PVDF膜的疏水性,但是PMMA的加入会使PVDF膜的β晶型增加,膜污染严重。因此,加入与PVDF半相容的高聚物聚砜(PS)作为第三相,从而制备共混膜。PMMA的加入可使PVDF的疏水性能得到很好的改善,接触角由90度下降到了70度,PS的加入可使PVDF/PMMA共混膜的污染率由40%下降到6.7%。在制备共混膜之前,通过共溶剂法、溶解度参数法、粘度法、玻璃化转变温度(DSC)法考察了PVDF/PS/PMMA三元体系的相容性。实验结果表明,溶解度参数法、粘度法同样可使用于三元共混体系。PVDF/PS/PMMA为半相容体系。选择最优共混比为A=9:1;B=8:2制备了PVDF/PS/PMMA三元共混膜。考察了共混物的高聚物浓度、添加剂分子量和添加剂种类对共混膜结构和性能的影响,在高聚物浓度为15wt%,使用PEG6000为添加剂制备的共混膜最优。更多还原

【Abstract】 PVDF membrane is an excellent polymer membrane used in the Separation field. But PVDF membranes have a stronger hydrophobic nature and easy-polluting by protein molecules, so modification of PVDF membrane is requested. The modification of PVDF membrane can broaden its application areas and make it better application in water-based systems. This study prepared PVDF membrane and blend with PS and PMMA to modification the stronger hydrophobic nature and easy-polluting character of PVDF membrane.Prepared PVDF membrane used immerged phase-inversion method. The influencing factors of PVDF membrane structure and performance are studied. These influencing factors include PVDF concentration, additive concentration, solvent species and the temperature of coagulation bath. when the concentration of PVDF is 14wt%, the structure of prepared PVDF is the best; When the concentration of additive is 4wt%～6wt%, can fully formatted pore structures; When DMF and DMAc as solvent, the structure and performance of PVDF membrane is not much difference; when Coagulation bath temperature is 20℃, the structure of prepared PVDF is the best.Chose PM\MA as the hydrophilic substance improved the hydrophobic property of PVDF, PMMA can effectively reduce the contact angle of PVDF membrane from 90 to 70 degree. But the adding of PMMA can Increase the crystalβ. As we know, due to piezoelectricity ofβ-crystal, it’s the main reason cause protein adsorption. So we blend with PS to reduceβ-crystal as a semi-compatible polymer. Contamination rate of PVDF/PA/PMMA blend membrane can decrease from 40% to 6.7%.The compatibility of polymer is important to the characteristics of blend membrane. Studied the compatibility of PVDF, PS and PMMA used co-solvent method, solubility parameters method, viscosity method and DSC etc. The results showed that the PVDF/PS/PMMA blend system is semi-compatible.The best blend rate is: A=9:1; B=8:2. Prepared PVDF/PS/PMMA blend membrane on this blend rate. Studied the effect of polymer concentration, molecule weights of additions and addition species on PVDF/PS/PMMA blend membrane. Prepared the blend membrane with polymer concentration is 15wt%, use PEG6000 as the addition, the blend membrane could be best.更多还原