Study on the effects and properties of hydrophobic poly(tetrafluoroethylene) membrane

Hydrophobic poly(tetrafluoroethylene) (PTFE) flat-sheet membranes were fabricated from a mixture of PTFE emulsion and polyvinyl alcohol (PVA) aqueous solution. Effects of blend ratio of PTFE to PVA on the morphology and properties of the membrane were investigated. Morphologies of obtained membranes were observed by field emission scanning electron microscopy (FESEM). Unique PTFE ‘worm-like’ crystals were observed in the PTFE membranes after sintering. As the PTFE/PVA mass ratio increased, the growth of the ‘worm-like’ crystals improved the hydrophobicity and mechanical strength of PTFE membrane. Moreover, membranes were tested in vacuum membrane distillation (VMD) configuration, using distilled water as feed. The VMD flux increased at first and then decreased with the PTFE/PVA mass ratio rising from 1:1 to 4:1 owing to the change of membrane porosity.

Research highlights
► Unique‘worm-like’crystals were observed in PTFE membrane.
► The ‘worm-like’crystals brought about the enhancement of membrane hydrophobicity.
► The‘worm-like’ crystals improved the mechanical strength of PTFE membrane.