Studies On Preparation Of IPP Hollow Fiber Microporous Membrane Via Thermally Induced Phase Separation

The iPP membrane via thermally induced phase separation (TIPS) has a series of advantages than one via melt spinning-cold stretching, such as higher permeability, narrower pore size distribution, and better mechanical properties.IPP hollow fiber microporous membrane were prepared successfully via thermally induced phase separation (TIPS) with iPP as materia,δand water as quench medium respectively, in this work, an organic liquidγwas introduced into the inner orifice firstly. The effect of melt index of iPP,cooling rate and velocity of diffusion on morphology and performance of iPP hollow fiber microporous membrane were studied.The matheatics model to calculate evaporation of solvent and velocity of heat transfer was proposed, inorder to find a way for improving the membrane properties and optimizing the spinning process. The result indicated that the cooling rate in outer surface of membrane is faster than that in inner surface of membrane, thus, the structure formed of membrane is asymmetric. The theory of diffusion and mass transfer was used for analysing the effect of diffusion and mass transfer between pore oil,quencher medium and diluent on morphology and performance of iPP hollow fiber microporous membrane.IPP hollow fiber microporous membrane was firstly prepared via thermally induced phase separation (TIPS) withγas bore liquid,δas quenching bath. It is indicated that morphology of the inner hollow fiber microporous membrane obviously improved and exhibits a fiber network structure which has high connectivity ,compared with the cellular structure with N2 as pore oil. Morphology of the outer hollow fiber microporous membrane exhibits an open and anomalistic cellular structure withδas quench medium;but it became a small cellular structure with water as quench medium and the number of pore is less. When the temperature of quenching bath goes up, the pure water flux and the mean pore size increase but the mechanical strength and the resistance to stress decrease. It is discovered that the mean pore size,the pure water flux,porosity and the the mechanical strength increase withδas quench medium compared with water as quenching bath. It is suggested that a solvent with high boiling point,low heat transfer and good solubility to diluent can greatly improved membrane performance.The result suggests the cooling rate and mass transfer is main cause for the morphology and performance of membrane formed, and cosolvent compositionαhas little influence on the morphology and performance of membrane. When the speed of winder increase, d0,di and L of hollow fiber microporous membrane decrease, but the pure water flux of hollow fiber microporous membrane increase.