【作者】 窦冠显；

【导师】 覃小红；

【作者基本信息】 东华大学 ， 纺织材料与纺织品设计， 2011， 硕士

【摘要】 目前,静电纺丝已成为制备超细和纳米纤维及其制品的一种重要方法。纳米纤维毡即采用非织造布作为接收基布,将静电纺纤维喷覆在其表面制备得到。与传统方法制得的纤维毡相比,纳米纤维毡具有重量轻、比表面积大和阻隔性好等众多优点,在过滤、保温、防护等方面有着广泛的应用前景。PVA有优良的物理性能、生物降解性能、在干态下有很好的机械性能,而且价格便宜,原料易得,是静电纺纳米纤维的主要用料,但因其分子中含有大量的羟基,亲水性强,耐水性能较差限制了它的应用。因此,需要对PVA进行改性,实现PVA纳米纤维毡的抗水解性能,从而拓宽静电纺PVA制品的用途特别是过滤方面的应用。PVA耐水改性方法大致分为物理改性和化学改性。本文从减少PVA分子中的羟基数目出发,主要研究利用其他试剂对PVA进行耐水改性的化学方法。研究初期,本文选择了尿素、草酸、马来酸以及戊二醛等试剂分别对PVA水溶液进行了耐水改性的探索。结果显示,尿素对PVA改性后,静电纺丝效果较好,但抗水解效果较差,而草酸和马来酸对PVA的酯化改性溶液,不能进行正常的静电纺丝,戊二醛可与PVA溶液直接发生缩醛化反应,反应过程难以控制,PVA凝胶化现象严重,不能用于静电纺丝。其次,基于其它研究报告,本文采用戊二醛(GA,25%水溶液)、丙酮和少量盐酸配制成不同GA浓度的改性溶液,采用直接浸渍方法交联PVA纳米纤维毡,研究了不同浓度改性液在不同的改性：时间下对PVA纳米纤维毡直观性能的影响,并对其表面形态和结构性能进行了研究,结果表明,改性后的纳米纤维毡有良好的抗水解性：能,并指出改性溶液的GA浓度对PVA纳米纤维毡性能有较大影响,而改性时间影响不大。在成功制备抗水解PVA纳米纤维毡的基础上,本文采用GA(50%水溶液)配制了12种不同浓度的改性液,首次通过直观感官表征和抗水解性能测试结合,系统地研究了不同浓度的GA改性液对两种醇解度PVA纳米纤维毡的改性效果,结果显示,GA浓度在3%-15%范围内时,两种醇解度PVA纳米纤维膜的改性效果均较好。重点对改性效果较好的纳米纤维毡利用SEM和FTIR进行了表征,同时也对其力学,热稳定性以及结晶度变化等进行了分析。最后,研究了5%GA改性PVA纳米纤维毡的过滤性能,结果表明,基布的平均孔径在112μm左右,铺上PVA纳米纤维膜的平均孔径最大仅为3.37μm,且非织造基布的孔径分布离散度比纳米纤维毡的孔径分布离散度大,说明了纳米纤维膜的附着有效的降低了基体材料的孔径尺寸。水通量和截留率的分析得知,抗水解PVA纳米纤维毡具有较高的水通量和截留率,过滤性能较好。另外,作为本文的延伸,创新性的采用无水乙醇取代丙酮作为改性溶剂,对PVA纳米纤维毡进行耐水改性,可在实现其较好抗水解效果的同时,创造一个相对良好的改性实验环境。更多还原

【Abstract】 Recently, Electrospinning has become an important method in fabricating of nanofibrous structures. Non-woven fabrics are used as substrates to receive polymer nanofibers, and in this process nanofiber mats are formed. Compared to traditional nonwoven fiber mat, nanofibrous mats have many advantages, such as light weight, high specific surface area and good protection, so that nanofibrous mats have extensive application prospects in the filtration, thermal insulation, protection and so on. PVA is the main electrospun material with excellent physical properties, biodegradability, good mechanical properties in the dry state, and many other advantages such as low price and easy to get, etc. However, PVA has a poor water resistance result from a large number of hydroxyl groups in molecules which limits its application. So, PVA was modified to achieve water-resistant PVA nanofiber mats, which can broaden the application of PVA nanofiber mats especially the application of filters.Methods of improving the water resistance of PVA can be divided into physical modification and chemical modification. In this paper, the method of chemically modified by other agents was studied.Urea, oxalic acid(OA), maleic acid(MA), and glutaraldehyde(GA) were chosen to modified PVA solution firstly.The results showed that the spinnability of PVA modified by urea was good but the prepared mat was water-soluble; the spinnability of PVA modified by OA or MA was bad which can not be used in electrospinning; PVA can be reacted with GA directly but the gelation make electrospinning impossibility.Then, the PVA nanofiber mats were prepared by electrospinning and immersed in a given concentration of GA(25% aqueous solution)and trace HCl in acetone solution.The effect on water resistance of PVA was discussed by selected different concentrations of modified solution under different modification time, then characterized by Scanning Electron Micrograph (SEM) and Fourier Transform Infrared (FTIR) spectrometry. The resulting crosslinked PVA substrates showed excellent water resistance,and the variation of time had little effect on the crosslinking reaction while the concentration of GA had greater impact.On the base of successful preparation of water-resistant PVA nanofiber mats,in this study, 12 different concentrations of GA (50% aqueous solution)in acetone solution were employed to modify 88% PVA and 95% PVA nanofiber mats,the modified effect were studied systemic by the integration of visual sensory evaluation and water durability measurements firstly. The results showed that the modified effect of two different PVA nanofiber membrane were good. SEM and FTIR were employed to characterize the better nanofiber mats, as well as the mechanical, thermal stability and crystallinity changes were analyzed.The filtration performance of 5% GA modified PVA nanofiber mats was studied, and results showed that the average pore size of nonwoven substrate was about 112μm, while the largest average pore size of PVA nanofiber membrane was only 3.37μm, and the pore size distribution of nanofiber membrane was more concentrated, indicating that the attachment of nanofiber membrane effectively reduce the pore size of substrate material. The water-resistant PVA nanofiber mats exhibited a high flux rate and an good rejection rate. In addition, Ethanol as solvent, different concentrations of GA modified solution were prepared, and the modified results showed a good effect and a better experimental environment.更多还原