超支化聚酯的亲水改性及其对PVA渗透汽化膜分离性能的影响

发布时间：2018-04-27 18:26

  本文选题：超支化聚酯 + 亲水改性　； 参考：《长春工业大学》2015年硕士论文

【摘要】：渗透汽化是一种实验过程简单、高效节能的新型膜分离技术,尤其是用于有机物脱水领域。而有机物脱水对所用的膜材料的亲水性要求较高,聚乙烯醇(PVA)是一种优良的亲水性膜材料。为了使其更加适用于渗透汽化脱水,提高其应用范围和能力,目前的研究热点集中在对PVA膜进行改性方面。超支化聚酯是一种有着高度支化结构聚合物,它不易结晶、分子间不易发生缠绕、末端含有大量活性基团,并且其合成方法相对简单,使得其工业生产成本较低,因而引起了越来越多的关注。本文以2,2-双羟甲基丙酸为AB2单体,季戊四醇为核,在对甲苯磺酸催化条件下,通过“准一步”聚合法,合成了含有端羟基的超支化聚酯(HBPE),利用顺丁烯二酸酐对HBPE的末端进行接枝反应,成功完成了其端基的改性,最终合成了水溶性超支化聚合物(WHBP),通过核磁和红外表征确定了HBPE已经成功完成端基的改性。然后以戊二醛为交联剂,制备了一系列不同比例的新型WHBP/PVA交联膜,通过傅里叶红外光谱(FTIR),X射线衍射(XRD),扫描电镜(SEM),机械强度,热重分析(TG)和水接触角等测量与表征,分析了和评价了该系列膜的物理化学特性。结果表明WHBP/PVA膜具有良好的热力学稳定性,较强的机械性能和高的亲水性。研究了不同含量的WHBP/PVA膜在正丁醇和水中的吸附和扩散行为,结果表明WHBP/PVA膜对水有较强的选择性吸附,并且随着WHBP含量的增加,吸附选择性增强,说明加入的WHBP增加了PVA膜的亲水性能。实验还考察了WHBP含量对WHBP/PVA膜渗透汽化性能的影响,将WHBP/PVA膜用于研究分离60℃10 wt.%水/正丁醇体系。具体考察了WHBP的含量对渗透通量、分离因子和渗透汽化分离指数的影响,结果发现随着WHBP含量的增加,WHBP/PVA膜的通量是增加的,但伴随着分离因子的下降,这是膜在渗透汽化性能评价方面不可避免的现象。而渗透汽化指数(PSI)呈现了先增加后降低的趋势。M-3(10%)在60℃分离10%的水/正丁醇体系时拥有最高的PSI值2.31×105,表现出了最佳的渗透汽化性能。单从膜的内在属性方面,考察了WHBP的含量对渗透性和渗透选择性的影响,渗透性随着WHBP含量的增加而增加,相反,渗透选择性减少。含量为10%的WHBP/PVA膜(M-3)表现出较高的渗透性4.00×10-3 g m-1 h-1 kPa-1和良好的选择性785。研究结果表明,WHBP含量为10%的WHBP/PVA膜(M-3)具有相当好的渗透汽化分离效果,可以选择作为后续具体研究的对象。对于后续研究,主要考察了料液浓度和料液温度对WHBP/PVA膜分离性能的影响,结果发现随着料液浓度的增加,膜的PSI值始终都表现较高,说明本实验制备的WHBP/PVA膜的渗透汽化性能优越。温度对WHBP/PVA膜的影响较大,高温是有利于渗透汽化分离的。
[Abstract]:Pervaporation is a new membrane separation technology with simple experimental process and high efficiency and energy saving, especially in the field of organic dehydration. However, dehydration of organic compounds requires high hydrophilicity of membrane materials. PVA (polyvinyl alcohol) is an excellent hydrophilic membrane material. In order to make it more suitable for pervaporation dehydration and improve its application scope and ability, the current research focus is on the modification of PVA membrane. Hyperbranched polyester is a kind of polymer with highly branched structure. It is not easy to crystallize, is not easy to twine between molecules, has a large number of active groups at the end, and its synthesis method is relatively simple, which makes its industrial production cost low. As a result, more and more attention has been paid. In this paper, in the presence of 2-dimethylolpropionic acid as AB2 monomer, pentaerythritol as nucleus and p-toluenesulfonic acid as catalyst, the polymerization was carried out by "quasi-step" polymerization. The hydroxyl terminated hyperbranched polyester (HBPEE) was synthesized. Maleic anhydride was used to graft the end of HBPE, and the modification of its terminal group was successfully completed. Finally, the water-soluble hyperbranched polymer (WHBP) was synthesized, and the modification of the terminal group of HBPE was confirmed by NMR and IR characterization. A series of novel WHBP/PVA crosslinking films with different proportions were prepared with glutaraldehyde as crosslinking agent. The WHBP/PVA films were measured and characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), mechanical strength, thermogravimetric analysis (TG) and water contact angle. The physicochemical properties of the films were analyzed and evaluated. The results show that WHBP/PVA film has good thermodynamic stability, strong mechanical properties and high hydrophilicity. The adsorption and diffusion behavior of WHBP/PVA membrane with different contents in n-butanol and water were studied. The results showed that WHBP/PVA membrane had strong selectivity to water, and the adsorption selectivity increased with the increase of WHBP content. The results show that the addition of WHBP increases the hydrophilicity of PVA membrane. The effect of WHBP content on the pervaporation performance of WHBP/PVA membrane was also investigated. The WHBP/PVA membrane was used to study the separation of 10 wt.% water / n-butanol system at 60 鈩，

本文编号：1811815