Preparation And Performance Of Polyurethane Microporous Membranes

In this paper,Polyurethane(PU)microporous membrane was prepared by the wet film preparation and the effects of different types of modifier lithium(Licl、PVP、PEG),inorganic modifier including(SiO2、CaCO3、BN)and polymer(CS)on membrane structure,membrane formation rate and permeability,water flux,hydrophilic on PU membranes were discussed.The PU-BN microporous membrane was prepared and effects of different GF-BN additions on the structure and properties of polyurethane films were discussed.The internal and surface pore structure of PU film were optimized by adding different types of porous agents.After the addition of porogen PVP and PEG,the thickness of the epidermis of the membrane section gradually decreased,the number of holes in the porous layer increased,the connectivity between the holes became better,and the formed membrane holes were more neat.With the increase of PVP addition,the pore size of the surface layer of the film increased.When Licl was added and the addition was less than 3%,the macroporous structure still existed in the PU membrane section structure,but the macroporous structure disappeared when the addition was more than 3%.Dense microporous structures were formed on the surface of the membrane,and the pore size was relatively uniform,but the pore size of the film surface was smaller than PEG and PVP.When the addition of porogen PVP is 5%,the comprehensive performance of the membrane is the best,and when the addion of porogen PEG and Licl is 3%,the comprehensive performance of the film is the best.Using inorganic particles SiO2 and CaCO3 as additives,the experimental results showed that after adding inorganic particles,the membrane forming rate was significantly increased and the microporous structure of polyurethane microporous membrane has been refined.Its water flux and air permeability have also been improved to some extent.When the addition of inorganic particles exceeds a certain value,the thickness of the upper cortex gradually thickens,the number of holes in the middle porous layer decreases,the pore size decreases,and the number of holes on the supporting layer is also significantly reduced.When the addtion of SiO2 is 3%,the comprehensive performance of polyurethane blend membrane is best.When CaCO3 addition is 2%,polyurethane blend membrane achieves the best comprehensive performance.BN with high thermal conductivity was added to the system to prepare permeable thermal membrane.After the addition of GF-BN,the micropore structure of PU microporous membrane was refined.The macroporous structure disappeared,the connectivity between the pores increased and the membrane structure characteristics tended to be stable.The per-meability and thermal conductivity of PU microporous membrane were improved obviously.The water flux,thermal stability and mechanical properties were improved to some extent,and the comprehensive performance of the permeable thermal conductive film was best when the addition amount of GF-BN was 0.4%.