Abstract: The effects of solubility parameter，boiling point，and surface tension of the extractant on the relative dimension of membrane prepared via thermally induced phase separation were studied.Membrane shrinkage was shown to increase with incrceasing surface tension，increasing boiling point，and incrceasing interaction with polymer. This demonstrated that the magnitude of capillary force，the length of the time during which capillary force is exerted on the pore wall，and the softening effect of extractant
greatly influenced the contraction of pores.

Key words: thermally induced phase separation, polypropylene membrane, extraction, drying