A water-soluble solvent

i.e.

epsilon-caprolactam (CPL)

was used as the diluent and microporous poly(phenylene sulfide) (PPS) membranes were prepared through the thermally induced phase separation method.One of the greatest advantages of using CPL is that the solvent is soluble to water and is able to be extracted by water

which is very clean and friendly to environment.By selecting a suitable composition

the pour-pressing process was used to make PPS flat membranes for performance and morphology characterization.The phase behavior of PPS/CPL blend was first depicted to identify the phase separation process of this binary system.The effects of cooling rate and polymer concentration on the morphologies and performances of PPS membranes were then investigated.The studies showed this binary system underwent solid-liquid phase separation via nucleation and growth of polymer crystals and then produced a structure described as polymer spherulite-like.The process upon slow cooling permits the system to develop into a leafy structure with more open pores and larger pore size than the rapid cooling process

which endows the membranes with a large permeation water flux.It was indicated through experiments that there was an operative window to prepare a poly(phenylene sulfide) membrane with pure water flux greater than 100 L/m2h and pore size about 4~5 m.The effect of polymer concentration was also studied and it was found that the permeability of microporous membranes decreased as the concentration of PPS increased.The membranes without any permeability were prepared when the polymer concentration was greater than 50 wt% due to too low porosity of the membranes.