【作者】 李宁；

【导师】 贺高红；

【作者基本信息】 大连理工大学 ， 膜科学与技术， 2008， 硕士

【摘要】 节能和环保是当今世界能源领域的两大主题,合理利用大气中丰富的氧资源是开发新能源的热点之一。与传统的深冷法和变压吸附法相比,膜法富氧具有流程简单,操作方便,能耗低,操作弹性大等优点,广泛应用于化工、医疗、冶金等行业。富氧膜材料有很多,其中硅橡胶由于透气性高而被广泛使用。但因其机械强度不高,一般将其复合在微孔基膜上制备成复合膜使用。复合膜的性能不仅取决于有选择性的表面皮层,而且受基膜材料、孔结构等因素的影响,因此合理选用与硅橡胶匹配的基膜是制备高性能富氧膜的关键。本文以聚碳酸酯(PC)、聚醚酰亚胺(PEI)、聚砜(PSF)作为基膜材料制备了硅橡胶复合膜,研究了不同铸膜液体系的相分离行为,考察了基膜材料及结构对复合膜性能的影响。论文首先考察了在25℃下沉淀剂水对PC、PEI和PSF三种铸膜液体系的相分离行为,并用线性浊点关系式(LCP关系)对铸膜液体系的浊点数据进行线性回归。由回归结果可知:线性回归曲线的斜率b相同时,截距数值|a|越大,沉淀剂对聚合物溶液的沉淀能力越强。实验中水对三种聚合物溶液的沉淀能力顺序为:PC＞PEI＞PSF。实验进一步考察了不同温度下非溶剂γ-丁内酯(γ-GBL)对PC铸膜体系相分离的影响,并依据LCP线性回归结果外推计算三元体系的双节线,由此得到了铸膜液体系中非溶剂添加剂的上限含量,为铸膜液体系的构建提供了可靠的依据。其次研究了制膜条件对基膜结构与性能的影响。分别选用PC、PEI和PSF为膜材料,以N-甲基吡咯烷酮(NMP)为溶剂,γ-GBL为添加剂,水为凝胶液,系统地研究了聚合物浓度和添加剂用量对膜结构和性能的影响。实验所制备的基膜均为指状孔结构,分离系数在0.9左右,其中PSF基膜的氧气渗透速率最大,为25700 GPU。以硅橡胶为选择层材料,采用浸渍涂敷法制备硅橡胶复合膜,系统地研究了聚合物浓度、添加剂用量及硅橡胶浓度对复合膜性能的影响。在具有稳定分离系数的前提下,以PC、PEI、PSF三种膜材料所制备的复合膜的最大氧气渗透速率分别为233、224和266 GPU。最后利用气体渗透阻力模型分析了基膜结构对硅橡胶复合膜性能的影响。随基膜孔径和孔隙率的增加,复合膜的氧气渗透速率增加;随着硅橡胶渗入率的增加,氧气渗透速率减小。更多还原

【Abstract】 Energy-saving and environmental protection are the main topics in current energy field worldwide.It has become an attracting problem to develop the oxygen resource in atmosphere as a new power properly.Compared with traditional cryogenic condensation and PSA method, membrane technology on oxygen enrichment is generally applied in chemical engineering, medicine,and metallurgy owing to the advantages of its simple process,easy operation,low energy consumption,and so on.Many polymeric materials have been reported to be good candidates of the membranes for oxygen enrichment.Polydimethylsiloxane（PDMS）is of special interest owing to its high intrinsic permeation rate and acceptable selectivity.But for its poor mechanical and film forming abilities,PDMS composite membrane is commonly utilized,in which PDMS as the active skin layer is coated on a porous polymeric support.The performance of composite membrane are determined by the selective layer,support membrane materials,and membrane morphology.It plays a crucial role to choose the suitable materials as support membranes for preparing high performance oxygen-enriched composite membranes.The objective of this work is to prepare PDMS composite membranes with polycarbonate（PC）,polyetherimide（PEI）and polysulfone（PSF）as support layer respectively and investigate the gas permeation performance affected by support layer materials and membrane morphology.The effects of H₂O on the behavior of phase separation of PC,PEI,and PSF three kinds of casting solution at 25℃were studied according to the linerized cloud point（LCP）correlation respectly.It could be seen that NSA coagulation ability was stronger when the intercept |a| was larger for the condition of the same slope of the simulated LCP line.The sequence of H₂O coagulation ability for the three polymers was as follows:PC＞PEI＞PSF.The effects of nonsolventγ-butyrolactone（γ-GBL）on the behavior of phase separation of PC casting solution were studied at different operating temperature according to the LCP correlation.It was found that the phase separation behavior of PC/NMP/γ-GBL also exhibited well agreement with the LCP correlation.Therefore,the maximum content ofγ-GBL in casting solution could be obtained according to the binodal line of the system,which provided scientific basis for the composition of casting solution.Support membranes were prepared by the dry/wet phase inversion method with PC,PEI, and PSF as membrane materials respectively.The effects of polymer concentration and the γ-GBL content of casting solution were studied.The membrane morphology was characterized with SEM and the gas permeation performance was carried out with pure O₂,N₂. The separation factor of the support membranes prepared showed were about 0.9,and the highest oxygen permeation rate was 25700 GPU under the operating parameters of 0.5MPa and 25℃.The composite membrane were prepared using PDMS as coating material with the dip-coating method.The influences of polymer concentration,additive content,and PDMS contents were systemically studied.The oxygen permeation rates of PDMS composite membranes with PC,PEI,and PSF as support membranes were 233,224 and 266 GPU respectly.Finally,the resistance model of composite membrane was employed to reserch the influences of support membrane on PDMS composite.The oxygen permeation rate of composite membrane increased as the pore size and porosity of support membrane increasing, and decreased as the filter ratio increasing.更多还原