Fabrication of hollow fiber microfiltration membrane from PVDF/DBP/DBS system via thermally induced phase separation process

摘要

Polyvinylidene fluoride (PVDF) membranes were prepared via a thermally induced phase separation (TIPS) process using mixed diluent consisting of dibutyl phthalate (DBP) and dibutyl sebacate (DBS). The compatibility between PVDF and mixed diluent was predicted via the solubility parameter theory and verified by experimental results. The effects of mixed diluent composition on cloud point temperature, crystallization temperature, crystallinity, crystal phase and morphology of the membrane were investigated. As a result, as DBS mass fraction in mixed diluent increased, the cloud point temperature and the crystallinity increased, the crystal phase transformed from beta phase to alpha phase and the morphology of the membrane cross-section changed from spherulitic structures to a bicontinuous structure. PVDF hollow fiber membranes were prepared successfully with the PVDF/DBP/DBS system via the TIPS method. The coagulant composition had a significant influence on the water permeability. When the dimethylacetamide (DMAc) content in the coagulant was 60%, the water permeability reached 877 l/m(2).h,while the rejection rate to the particles with a size of 200-500 nm was above 95%.