表面活性劑對PVDF中空纖維膜成膜過程的影響
發(fā)布時間：2019-01-19 16:12
【摘要】：聚偏氟乙烯(PVDF)是一種結(jié)晶性聚合物,機械性能較好,是綜合性能優(yōu)良的膜材料,PVDF分離膜因分離效率高、能耗低等優(yōu)點,越來越受到人們的重視,在分離領(lǐng)域得到了廣泛的應(yīng)用,但是傳統(tǒng)的多孔膜在制備過程中很容易形成相對致密的皮層,影響其滲透性能,大大阻礙了它的應(yīng)用,因此,調(diào)控分離膜結(jié)構(gòu)進而改變分離膜的性能成為研究熱點。實驗采用溶液相轉(zhuǎn)化法,通過在聚偏氟乙烯鑄膜液中添加特定親疏水平衡值(HLB)的復(fù)配表面活性劑Span80和Tween80,從而調(diào)控分離膜皮層的微觀結(jié)構(gòu)。提出一種表面活性劑對溶液相轉(zhuǎn)化法聚合物濃相區(qū)的界面活化作用原理,研究了表面活性劑的親疏水平衡偏移值(AHLB)對膜基本性能的影響。結(jié)果表明,溶液相轉(zhuǎn)化制備多孔膜的過程中,鑄膜液從穩(wěn)定區(qū)向不穩(wěn)定區(qū)過渡時,存在表面活性劑對聚合物濃相區(qū)的界面活化作用;當(dāng)表面活性劑的HLB接近于10時,表面活性劑對聚合物濃相區(qū)界面的活化作用最大,獲得了一種皮層開孔最多、本體阻力最小、最可幾孔徑向最大孔徑偏移的分離膜;此外,與不加表面活性劑的分離膜相比,分離膜的純水通量顯著提高了 277%,達到1015 L/(h·m2)。實驗通過固定表面活性劑的親疏水平衡值(HLB)的大小(HLB=10),改變鑄膜液中表面活性劑的含量,研究了表面活性劑的含量對膜基本性能的影響,例如分離膜的純水通量、本體阻力、固化速度、孔隙率、孔徑分布、SEM以及機械性能等;結(jié)果表明,類似臨界膠束濃度原理,表面活性劑對于聚合物濃相區(qū)的界面活化作用,也存在臨界值。隨著鑄膜液中表面活性劑的含量不斷增大(0%-3%),分離膜的純水通量逐漸升高,皮層開孔增多;在這過程中,當(dāng)表面活性劑的含量達到1.5%,純水通量達到1015 L/(h.m2),皮層開孔最多,繼續(xù)增大表面活性劑的含量,膜透水通量和皮層開孔數(shù)量都不再明顯變化。本文提出了一種新的皮層結(jié)構(gòu)控制方法,涉及到了一種新型的NIPS成膜機理,對于進一步研究溶液相轉(zhuǎn)化法成膜機理有一定的幫助。
[Abstract]:Polyvinylidene fluoride (PVDF) is a crystalline polymer with good mechanical properties and excellent comprehensive properties. Because of its high separation efficiency and low energy consumption, poly (vinylidene fluoride) (PVDF) has attracted more and more attention. It has been widely used in the field of separation, but the traditional porous membrane is easy to form a relatively dense cortex during the preparation process, which affects its permeability and greatly hinders its application. It has become a hot research topic to regulate the structure of separation membrane and change the performance of separation membrane. The solution phase inversion method was used to regulate the microstructure of the membrane cortex by adding Span80 and Tween80, to the solution of polyvinylidene fluoride (PVDF) casting membrane with special hydrophobic equilibrium value (HLB). The principle of surfactant interface activation in solution phase inversion method was proposed. The effect of hydrophobic equilibrium shift value (AHLB) of surfactant on the basic properties of the membrane was studied. The results show that in the process of preparing porous membrane by phase transformation of solution, there exists the interface activation of surfactant in the thick phase region of polymer during the transition of casting liquid from the stable region to the unstable region. When the HLB of the surfactant is close to 10:00, the surfactant has the largest activation effect on the interface of the polymer in the dense phase region, and a separation membrane with the most cortical pore opening, the smallest bulk resistance and the best migration of the pore size to the maximum pore size is obtained. In addition, compared with the membrane without surfactant, the pure water flux of the membrane increased by 277L / (h ~ 2) to 1015 L / (h ~ 2). The hydrophobic equilibrium value (HLB=10) of fixed surfactant was determined to change the content of surfactant in casting solution. The effect of surfactant content on the basic properties of the membrane was studied, such as the pure water flux of the membrane. Bulk resistance, curing rate, porosity, pore size distribution, SEM and mechanical properties; The results show that, similar to the critical micelle concentration principle, there is a critical value for the interfacial activation of polymer dense phase region by surfactants. With the increasing of surfactant content (0-3%), the pure water flux of the membrane increased and the opening of the cortex increased. In this process, when the surfactant content reaches 1.5g, the pure water flux reaches 1015 L / (h.m2), the cortical pore opening is the most, and the surfactant content continues to increase, the membrane permeation flux and the cortical pore number do not change obviously. In this paper, a new control method of cortical structure is proposed, which involves a new mechanism of NIPS film formation, which is helpful to further study the mechanism of solution phase inversion method.
【學(xué)位授予單位】：天津工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ051.893
本文編號：2411525
[Abstract]:Polyvinylidene fluoride (PVDF) is a crystalline polymer with good mechanical properties and excellent comprehensive properties. Because of its high separation efficiency and low energy consumption, poly (vinylidene fluoride) (PVDF) has attracted more and more attention. It has been widely used in the field of separation, but the traditional porous membrane is easy to form a relatively dense cortex during the preparation process, which affects its permeability and greatly hinders its application. It has become a hot research topic to regulate the structure of separation membrane and change the performance of separation membrane. The solution phase inversion method was used to regulate the microstructure of the membrane cortex by adding Span80 and Tween80, to the solution of polyvinylidene fluoride (PVDF) casting membrane with special hydrophobic equilibrium value (HLB). The principle of surfactant interface activation in solution phase inversion method was proposed. The effect of hydrophobic equilibrium shift value (AHLB) of surfactant on the basic properties of the membrane was studied. The results show that in the process of preparing porous membrane by phase transformation of solution, there exists the interface activation of surfactant in the thick phase region of polymer during the transition of casting liquid from the stable region to the unstable region. When the HLB of the surfactant is close to 10:00, the surfactant has the largest activation effect on the interface of the polymer in the dense phase region, and a separation membrane with the most cortical pore opening, the smallest bulk resistance and the best migration of the pore size to the maximum pore size is obtained. In addition, compared with the membrane without surfactant, the pure water flux of the membrane increased by 277L / (h ~ 2) to 1015 L / (h ~ 2). The hydrophobic equilibrium value (HLB=10) of fixed surfactant was determined to change the content of surfactant in casting solution. The effect of surfactant content on the basic properties of the membrane was studied, such as the pure water flux of the membrane. Bulk resistance, curing rate, porosity, pore size distribution, SEM and mechanical properties; The results show that, similar to the critical micelle concentration principle, there is a critical value for the interfacial activation of polymer dense phase region by surfactants. With the increasing of surfactant content (0-3%), the pure water flux of the membrane increased and the opening of the cortex increased. In this process, when the surfactant content reaches 1.5g, the pure water flux reaches 1015 L / (h.m2), the cortical pore opening is the most, and the surfactant content continues to increase, the membrane permeation flux and the cortical pore number do not change obviously. In this paper, a new control method of cortical structure is proposed, which involves a new mechanism of NIPS film formation, which is helpful to further study the mechanism of solution phase inversion method.
【學(xué)位授予單位】：天津工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ051.893
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