Optimization of structure and properties of polyphenylene sulfide porous membrane by controlling the process of thermally induced phase separation

Polyphenylene sulfide (PPS) porous membranes were successfully prepared from miscible blends of PPS and polyethersulfone (PES) via thermally induced phase separation followed by subsequent extraction of the PES diluent. The morphologies, crystalline structures, mechanical properties, pore structures and permeate fluxes of the PPS porous membranes obtained from different phase separation processes were characterized and are discussed. During the phase separation in the heating process, PPS and PES mainly underwent liquid-liquid phase separation, and then a nonhomogeneous porous structure with a mean pore size of 100 mu m and a honeycomb-like internal structure formed on the membrane surface. The phase separation of PPS/PES occurring in the cooling process was easier to control and the related pore diameter distribution was more regular. In the process of direct annealing, as the phase separation temperature decreased, the pore size distribution became more homogeneous and the mean diameter of the pores also decreased gradually. When the phase separation temperature decreased to 200 degrees C, PPS membranes with a network structure and a uniform as well as well-interconnected porous structure could be obtained. In addition, the maximum permeation flux reached 1718.03 L m(-2) h(-1) when the phase separation temperature was 230 degrees C. The most probable pore diameter was 6.665 nm, and the permeate flux of this membrane was 2.00 L m(-2) h(-1); its tensile strength was 17.07 MPa. Finally, these PPS porous membranes with controllable pore structure as well as size can be widely used in the chemical industry and energy field for liquid purification. (c) 2020 Society of Chemical Industry