The effect of binary diluents on the performance of ultrahigh molecular weight polyethylene/SiO₂ hybrid hollow fiber membrane

Ultrahigh molecular weight polyethylene (UHMWPE)/SiO₂ hybrid hollow fiber membranes were prepared by thermally induced phase separation (TIPS) using mineral oil as the first diluent, polyethylene oxide (PEO) as the second diluent, and SiO₂ as additive. The effect of PEO on the rheological behavior, FTIR-ATR spectra, phase diagram, morphology, and permeability was investigated. The results suggested that a proper amount of PEO can decrease the viscosity of UHMWPE/diluent appropriately. Because PEO and UHMWPE were incompatible, the miscibility of membrane dope could be changed by PEO, which directly affect the phase separation. It was also discovered that a spherulite structure, coming from solid–liquid (S-L) TIPS, was built at any UHMWPE concentration without PEO. Whereas, an open-cell porous structure with better connectivity, owing to liquid–liquid (L-L) phase separation, was produced after adding PEO. The permeability increased firstly, and then decreased because excessive PEO was sensitive for agglomeration. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012