TIPS behavior for IPP/nano-SiO 2 blend membrane formation and its contribution to membrane morphology and performance

In the present work, the TIPS behavior of isotactic polypropylene (iPP)/di-n-butyl phthalate (DBP)/dioctyl phthalate (DOP)/nano-SiO2 system and the competition relation between liquid–liquid phase separation and polymer crystallization are successfully adjusted by adding nano-SiO2. The liquid–liquid phase separation temperature of the system increases with increasing nano-SiO2 content. Besides, iPP crystallization temperature is also changed after adding nano-SiO2. IPP/nano-SiO2 blend hollow fiber microporous membrane is prepared via TIPS method. SEM photos show that the membrane exhibits mixed morphology combining cellular structure relating to liquid–liquid phase separation and branch structure originating from polymer crystallization. The relative weight of cellular structure first decreases and then increases with the increase of nano-SiO2 content. Furthermore, porosity, connectivity among pores and pure water flux of the membrane first increase and then decrease with increasing nano-SiO2 content. However, mechanical performance of the membrane is improved at all times with increasing nano-SiO2 content.