Polytetrafluoroethylene (PTFE) flat sheet membranes were prepared through casting and sintering methods. The effect of sodium benzoate salt on the characteristics of PTFE flat sheet membranes such as morphology, surface roughness, porosity, mechanical strength and crystallinity were studied through scanning electron microscopy (SEM), atomic force microscopy (AFM), mercury intrusion porosimetry, tensile test and X-ray diffraction (XRD). SEM analysis confirmed the formation of irregular porous microstructures in sponge-like configuration. All the fabricated membranes exhibited narrow pore size distributions and have relatively small average pore diameters between 0.074 and 1.068 µm despite having porosity between 36.41 and 74.32 %. In addition, the roughness of the PTFE flat sheet membranes increased as the sodium benzoate content increased. Increasing sodium benzoate content was positive for pore size, porosity and roughness but negative for surface roughness and mechanical properties. This research confirmed that the addition of sodium benzoate salt in aqueous PTFE solution is a useful approach for the fabrication of porous PTFE flat sheet membranes
Polytetrafluoroethylene (PTFE) flat sheet film was modified with acrylic acid (AAC) by radiation induced grafting polymerization (RIGP) method using electron beam. The adsorbed doses were varied from 10 to 50 kGy, time of grafting from 1 to 3 h and monomer concentration and temperature were kept constant at 30 wt. % and 40ºC. The degree of grafting (D g) and equilibrium degree of swelling (EDS) of the grafted films were then determined. The films were further characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), atomic force microscope (AFM), X-ray diffraction (XRD), and optical water contact angle. D g within the range of 17% to 210% were obtained for doses from 10 to 50 kGy within time of grafting from 1 to 3 h. The grafted film (PTFE-g-AAC) showed increased hydrophilicity leading to an increase in EDS. The successful grafting process was confirmed by FTIR results that showed characteristics peaks for carbonyl and hydroxyl group and a decrease in crystallinity for the PTFE-g-AACfilm. SEM images showed that PTFE-g-AAC films had less fibrillar compared to PTFE film and was consistent with the decrease in roughness for the PTFE-g-AAC film. This study indicated that modifying PTFE film by grafting AAC could significantly improve the hydrophilicity of PTFE film. The PTFE-g-AAC films has potential as a heavy metal adsorbent as it can remove at least 75% of Fe ion and 50 % of Pb ion from competitive media.
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