Highly hydrophobic microporous low-density polyethylene hollow fiber membranes by melt-extrusion coupled with salt-leaching technique

Microporous and highly hydrophobic low-density polyethylene (LDPE) hollow fiber membranes were successfully prepared via a solvent-free method, combining melt-extrusion, and salt-leaching techniques. NaCl particles with particle size of 510 mu m were mixed with LDPE pellets to produce a blend of 35, 40, 50, 60, 65 and 68wt% of salt. A microporous structure was produced by leaching the salt particles from the hollow fiber matrix via immersion in water at 60 degrees C. The fabricated membranes were then characterized in terms of morphology, porosity and pore size distribution, surface roughness, and hydrophobicity, as well as mechanical properties. The remarkable increase in the water contact angles from 98 degrees for LDPE hollow fibers fabricated without the addition of salt (blank sample) to 130 degrees for membranes fabricated with initial salt content of 68 wt% is mainly attributed to the rough surface structure, comprising a large number of micropapillas produced by removing the imbedded salt crystals. The increase in surface roughness and porosity of hollow fiber membranes with increasing initial salt content was confirmed by scanning electron microscope and atomic force microscopy. Copyright (c) 2013 John Wiley & Sons, Ltd.