聚四氟乙烯中空纤维膜的制备及其工艺的探究

发布时间：2018-02-11 01:43

  本文关键词： PTFE中空纤维膜 润滑剂 挤出工艺 拉伸工艺 烧结工艺　出处：《浙江理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：中空纤维膜由于其占地面积小、填装密度大、利用率高、易放大、清洗简便等特点,被广泛应用于超滤、微滤、反渗透、气体分离器等传统和新型的膜分离组件形式[1,2]。此外,由于聚四氟乙烯中空纤维膜力学强度高、耐酸碱、耐高低温、表面摩擦系数低等特点,在特种过滤、气体吸收、臭氧溶解过滤、膜蒸馏等领域应用潜力大[3]。本文采用聚四氟乙烯分散树脂为原料,加入埃克森美孚异构烷烃类Isopar系列润滑剂,通过糊料挤出和拉伸成型的方法,制备PTFE中空纤维膜。采用挤出平均压力、孔径和泡点压强、孔隙率、水通量、接触角、SEM和DSC等测试来表征PTFE中空纤维膜的结构与性能。实验主要探讨润滑剂(种类和配比)、挤出工艺(压缩比、长径比和锥角)和拉伸烧结工艺对PTFE结构和性能的影响,优化各工艺参数,为PTFE中空纤维膜的生产提供指导。具体研究内容如下:(a)实验改变润滑剂参数(包括润滑剂种类、配比),通过“混合→预成型→挤出→拉伸→烧结→自然冷却”的工艺路线制备PTFE中空纤维膜。实验通过探究润滑剂的种类和配比对PTFE中空纤维膜的结构和性能的影响,得到润滑剂种类和配比的最佳组合,优化润滑剂。(b)通过改变挤出工艺模具的参数,探究压缩比RR、长径比L/D、椎角α对挤出压力、膜断裂强力、平均孔径、泡点压强、孔隙率和水通量的影响规律,得到最佳的挤出参数。(c)通过调节拉伸工艺参数(拉伸倍数和拉伸温度)和烧结工艺参数(烧结温度和烧结时间),探究拉伸烧结工艺对PTFE中空纤维膜平均孔径、泡点压强、孔隙率和水通量的影响规律,得到最佳拉伸烧结工艺参数,优化拉伸烧结工艺。实验结果表明:(1)润滑剂种类为IsoparG、配比为20%所得到PTFE中空纤维膜平均孔径小、泡点压强和孔隙率高、水通量大断裂强度和接触角大且挤出过程中挤出压力低。润滑剂含量过高或过低时,对PTFE中空纤维膜的结构和性能均有一定程度的不利影响。(2)当压缩比RR=185、长径比L/D=20、椎角α=40°时,挤出过程中挤出压力低、断裂强力大、平均孔径小、泡点压强高,孔隙率大、水通量高,可作为优良的PTFE中空纤维膜的挤出工艺参数。(3)拉伸和烧结工艺对PTFE中空纤维膜微孔结构性能的影响规律如下:随着拉伸倍数的增加,PTFE中空纤维膜的平均孔径、孔隙率大,泡点压强小,水通量大;随着拉伸温度的增加,PTFE中空纤维膜的平均孔径、水通量增大,孔隙率增加,泡点压强降低;随着烧结温度的增加,PTFE中空纤维膜的孔径,泡点压强、水通量降低,孔隙率无明显变化规律;随着烧结时间的增加,PTFE中空纤维膜平均孔径、孔隙率、水通量增加,泡点压强降低。拉伸工艺使PTFE制品的结晶度明显降低,烧结工艺使PTFE制品的结晶度进一步降低。在拉伸倍数100%、拉伸温度300℃、烧结温度320℃和烧结时间5min时,得到的中空纤维膜平均孔径小,泡点压强、孔隙率、水通量大。
[Abstract]:Hollow fiber membrane is widely used in ultrafiltration, microfiltration, reverse osmosis, gas separator and other traditional and new membrane separation module forms because of its small area, high filling density, high utilization ratio, easy amplification, easy cleaning and other characteristics. In addition, the hollow fiber membrane membrane is widely used in ultrafiltration, microfiltration, reverse osmosis, gas separator and other traditional and new forms of membrane separation components. Due to its high mechanical strength, acid and alkali resistance, high and low temperature resistance and low surface friction coefficient, PTFE hollow fiber membrane is used in special filtration, gas absorption, ozone dissolution filtration, etc. The application potential of membrane distillation is great [3]. In this paper, the polytetrafluoroethylene dispersion resin is used as raw material and ExxonMobil iso-alkane series Isopar lubricant is added. PTFE hollow fiber membrane was prepared. Extrusion average pressure, pore size and bubble point pressure, porosity, water flux were used. The structure and properties of PTFE hollow fiber membrane were characterized by contact angle scanning electron microscopy (SEM) and DSC. The effects of lubricant (type and proportion), extrusion process (compression ratio, aspect ratio and cone angle) and tensile sintering process on the structure and properties of PTFE were investigated. The process parameters are optimized to provide guidance for the production of PTFE hollow fiber membrane. The specific research contents are as follows: 1. The experiment changes the lubricant parameters (including lubricant type, ratio of lubricant), through "mixing" 鈫扨reforming. 鈫扙xtrusion. 鈫扴tretch. 鈫扴intering. 鈫扵he PTFE hollow fiber membrane was prepared by natural cooling process. The effects of lubricant type and ratio on the structure and properties of PTFE hollow fiber membrane were investigated in the experiment. The optimum combination of lubricant type and ratio was obtained. By changing the die parameters of extrusion process, the influences of compression ratio (RR), ratio of length to diameter (L / D), angle 伪 on extrusion pressure, film breaking strength, average pore size, bubble point pressure, porosity and water flux were investigated. The optimum extrusion parameters were obtained by adjusting the drawing process parameters (drawing ratio and drawing temperature) and sintering process parameters (sintering temperature and sintering time) to investigate the average pore size and bubble point pressure of PTFE hollow fiber membrane by drawing sintering process. The effects of porosity and water flux on the properties of PTFE hollow fiber membrane were studied. The optimum drawing sintering process parameters were obtained. The experimental results showed that the average pore size of PTFE hollow fiber membrane was small when the type of lubricant was Isoparg and the ratio of 20% was 20%. When the foam point pressure and porosity are high, the water flux is large, the contact angle is high and the extrusion pressure is low, the lubricant content is too high or too low. The structure and properties of PTFE hollow fiber membrane were affected to some extent. 2) when the compression ratio RRN 1855, the aspect ratio L / D 20, and the angle 伪 40 掳, the extrusion pressure was low, the fracture strength was large, the average pore size was small, the bubble point pressure was high, and the porosity was large. The effect of high water flux on the micropore structure and properties of PTFE hollow fiber membrane is as follows: with the increase of drawing ratio, the average pore size of PTFE hollow fiber membrane is increased. With the increase of tensile temperature, the average pore size of PTFE hollow fiber membrane increases, the water flux increases, the porosity increases and the bubble point pressure decreases, and with the increase of sintering temperature, the pore size of PTFE hollow fiber membrane increases. With the increase of sintering time, the average pore size, porosity and water flux of PTFE hollow fiber membrane increased, and the pressure of foam point decreased. The crystallinity of PTFE products was further reduced by sintering process. When drawing ratio 100, drawing temperature 300 鈩，

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