非對稱PTFE複合膜的製備與應用

本研究利用線棒塗佈機將PTFE懸浮微粒在同樣是PTFE拉伸薄膜的基材上，再利用紅外線加熱的方法，對PTFE微粒塗佈層進行熱處理來製備非對稱PTFE膜，並將所製備的薄膜應用在滲透蒸發、蒸氣透過、超過濾等分離程序。在製膜過程中，固定塗佈線棒規格、塗佈速度、以及加溫和冷卻的程序，而利用改變PTFE懸浮微粒濃度、燒結溫度及燒結時間等變數控制緻密層的孔洞大小及透過性。研究中，使用接觸角量測儀、掃描式電子顯微鏡及膨潤度測試、X光繞射儀、熱分析儀和毛細管流孔徑測定儀等儀器或方法來了解PTFE的性質與熱處理前後PTFE特性的改質。蒸餾水、異丙醇、乙醇、四氟丙醇四種溶劑由接觸角測量得知PTFE緻密膜面對蒸餾水的親和性最小，對異丙醇的親和性最大。從SEM圖中，可以發現在相同燒結時間內，薄膜表面孔洞大小隨著燒結溫度（高於熔點）的增高而變小；在相同燒結溫度下，膜表面孔洞大小隨燒結時間的增加而變小。在膨潤度測試中，PTFE懸浮微粒受異丙醇的膨潤效應顯著，但PTFE拉伸膜或是燒結後的PTFE微粒複合膜受異丙醇的膨潤程度很小。PTFE懸浮微粒在燒結前後的X光繞射儀（2θ~18°）繞射強度並沒有明顯的改變，但燒結前後的PTFE懸浮微粒的X光繞射儀（2θ~18°）繞射強度皆比PTFE拉伸膜還低。但在另一繞射角度（2θ~41°），燒結前的PTFE微粒膜的繞射強度卻最高；而在熱分析儀的測試中，發現燒結前的PTFE懸浮微粒比PTFE拉伸膜和燒結後的PTFE微粒複合膜的熔點與熔化熱還高，表示三者的結晶形態並不相同。 PTFE複合膜表面燒結溫度為500℃,1分鐘之PTFE微粒薄膜（非孔洞膜）進行90wt%乙醇水之滲透蒸發分離程序測試之透過量為100（g/m2-hr），出口水濃度為99wt%，選擇比為683；若表面燒結溫度425℃，5分鐘之PTFE複合膜（孔洞~0.09μm）則用於超過濾測試中得到不錯效果，和PVDF超過濾商業薄膜（MWCO＝30,000）對BSA和γ－globulins的過濾效能表現相當；表面燒結溫度425℃，3分鐘之PTFE複合膜（孔洞<0.09μm）則用於蒸氣透過，對5wt%異丙醇水溶液進料透過膜以後異丙醇可以高達50wt%以上，透過量為9.8（kg/m2-hr）。

關鍵字

超過濾；蒸氣透過；薄膜；滲透蒸發；鐵氟龍

並列摘要

The major aim of the present work is to study methods for making asymmetric PTFE membranes with small pores or without pores. First ,we use the bar coater to coat the PTFE suspended fine powders（particle size is about 0.05μm∼0.5μm） on the PTFE stretched membranes （pore size∼0.5μm）. Then we use the Infrared gold image furnace to heat the surface of the PTFE fin powders. After we finish the total processes for making the asymmetric PTFE membranes, we can use the membranes to apply on the ultra-filtration, nano-filtration, and reverse osmosis and so on. In the processes of making asymmetric PTFE membranes, we fix the type of the coating bar, the coating speed and the quenching temperature; In order to get the optimal conditions for making the asymmetric PTFE membranes, we change the concentration of the PTFE suspended fine powders, the sintering temperature and time or pressure. By using the contact angle meter, SEM, XRD, PMI, DSC or performing the degree of swelling test, we try to understand the properties of the PTFE in many forms. By the contact angle test, we know that the affinity to PTFE of iso-propanol is better; By the SEM, we know the pores on the surface of the sintered membranes are getting smaller and smaller with higher sintered temperature that is above the melt point of the PTFE. Similarly the pores on the surface of the sintered membranes are getting smaller and smaller with more sintered time on the sintered membranes（above the melt point of the PTFE）； By the degree of swelling test, PTFE suspended fine powders have high degree of swelling with organic solutes, but the degree of the swelling for the another PTFE membranes is tiny ; By the XRD, there is no change in the diffraction intensity（2θ∼18°） of the PTFE fine powders after sintering, the stretched PTFE membranes have the highest intensity（2θ∼18°）, but in another diffraction angle （2θ∼41°）, the PTFE fine powders have the highest intensity; By the DSC test, we find the PTFE fine powders have higher melt point and the enthalpy than stretched membrane or sintered membrane. We think the crystal form of the PTFE particles and PTFE membranes are not the same. When we control the sintered condition（500℃ and 1 min）, the PTFE asymmetric membranes is performed in pervaporation in the 90wt% ethanol aqueous solution. , the permeate flux is 100（g�m2-hr）and the concentration of the permeation is 99wt% water included; we control the condition （425℃ and 1 min）, the membranes are good for the ultra-filtration , the performance is similar as PVDF30,000; When the sintered condition is 425℃ and 3min, the PTFE asymmetric membranes can separate the iso-propanol and ethyl alcohol very well by vapor permeation.

並列關鍵字

VP ； UF ； membrane ； PTFE ； PV

參考文獻

Burshe, M. C., S. B. Sawant, J. B. Joshi, V. G. Pangakar,“Sorption and permeation of binary water—alcohol systems through PVA membranes crosslinked with multifunctional crosslinking agents”, J. Sep. and Puri. Tech., 12, 145,（1997）

Clark, E. S., “The molecular conformations of poly-tetra-fluoro- ethylene: forms II and IV”, Polymer ., 40, 4659, (1999)

Conesa, J. A., and R. Font, ”Polytetrafluroethylene Decomposition in Air and Nitrogen”, Polym, Eng, Sci., 41, 2137（2001）

Field, R. W., P. K. Ten, “Organophilic pervaporation：prospects and performance”, J, Chem.Eng., 73, 133（1999）

Huang, J., Y. C. Wang., C. L. Li., K. R. Lee., J. Y. Lai., “Effect of surface resintering on the surface morphology and vapor permeation properties of skived poly（tetrafluoroethylene） membranes”, Separ. Sci. Technol., 36, （12）, 2677 （2001）

國際替代計量

非對稱PTFE複合膜的製備與應用

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