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8.1.3 PEG Filtration MeasurementsThe Poly(ethylene glycol) (PEG) feed solution was prepared by weighing 0.25 g each ofdifferent PEGs ( 400 Da, 1450 Da, 4600 Da, 10 KDa and 35 KDa) ( Sigma-Aldrich®, 99.5 %) anddissolving in ultrapure water to obtain a 1g.l -1 solution, stirred overnight. This solution was filled intothe reservoir of the setup described above and a small glass vial was attached to the outlet of thecell containing the membrane. Approximately 2 ml of permeates were collected after certaininterval of time successively at a given pressure difference.8.1.4 Self-Healing MeasurementsAfter being subjected to water pressure a first time to measure the flux evolution as areference using the above discussed set-up, the pressure was relieved and each membrane film wascarefully removed along with its non-woven substrate from the filtration cell. The removedmembrane was then transferred onto humid silicon water. A single perforation was created in thehydrated membrane using a solid body – 8.2a, b). Theneedle was put into contact with the assembly of membrane film/polyester fabric, piercing till thesilicon surface so as to obtain better reproducibility in terms of perforation diameter. After theperforation, the membrane/fabric assembly was again encased into the filtration cell and waterpermeation test were resumed. The whole process of disembarking of membrane, perforation andits re-embarking was accomplished with five minutes to minimize the effects of the developedpressure change.Figure – 8.2: Scanning Electron Microscopy images of, a-b) Tip of the needle to make perforation in the films.144