Preparation and application of asymmetric PTFE composite membrane
Date Issued
2004
Date
2004
Author(s)
Hsueh, Ting-Hsiang
DOI
zh-TW
Abstract
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.
Subjects
超過濾
蒸氣透過
薄膜
滲透蒸發
鐵氟龍
VP
UF
membrane
PTFE
PV
Type
thesis
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