The Fabrication Of PA6 Mass Nanofibrous Membranes For Low Pressure Air Filtration Via Electrospinning

In recent years,as the industrials production and transportation rapidly developing,a few relatively pollutants were released into the atmosphere,causing pollution to the atmospheric environment.Tiny particles with bacteria,pathogens and toxic can be absorbed into lung through breathing,which do serious harm to people's health.How to effectively alleviate the effect of air pollution on people's lives must be solved.Electrospinning nanofiber membranes with a small fiber diameter,large specific surface area,the network structure,as well as good pore connectivity,which can be used as a novel kind of fiber filter effectively to remove the tiny particles in the air.However,the electrospinning membranes present high resistance in air filtration.In this paper,in order to obtain high efficiency filter material with low resistance to achieve the purpose of purifying air,a variety of composite nanofibrous membrane filters were prepared by electrospinning technique.The main research contents are as follows:1.Study on PA6/PVP blending nanofibrous membranes.The PA6 solution concentration and the amount of PVP which play important roles on the membrane surface morphology,mechanical properties and hydrophilic properties were discussed.When the spinning PA6concentration of 28%and the amount of 0.5 g PVP were determined,the diameter of the fibers became 132 nm,fracture strength was 9.68 MPa,the elongation at break was 31.89%,and the hydrophilic angle of 32.4°±1.2,the nanofibrous membranes are optimal.Furthermore,the membranes of different spinning time were performed on 300 nm DOP aerosol particles to evaluate its filtration performance with different spinning time membranes.The experimental results indicate that the membrane of 0.5 h spinning time get 99.5%filtration efficiency and 475Pa pressure drop under the face velocity of 14.2 cms^-1.The membrane got a high efficiency and high resistance with the spinning time continuing,while the pressure drop would get down as the face velocity decreased.The membranes exhibited better filter for removing large particles size,which is expected to achieve its application in humidifier wet film materials.2.Study on PA6/PTT multileveled layers structured nanofibrous membranes.The PA6/PTT nanofibrous membranes were fabricated with polyamides 6(PA6)dissolved in formic acid and polyethylene terephthalate(PTT)dissolved in TFA/DCM mixed solvents with different assembled structures.The morphology,fiber diameter and distribution and tensile strength determined by the assembled structure were discussed.Additionally,the measurements of filtration efficiency and estimation of pressure drop were performed a series size of DOP particles,different air flow rates,and a long time.The correlation of the efficiency and pressure drop between DOP particle size,air face velocity and the membrane structure were also studied.The results revealed that the sample PTT/PA6 membrane as the best one for filtration combined137 Pa drop pressure and 93.726%filtration efficiency.The comparison of pure PA6 nanofiber media,characterized by 97.787%and 467 Pa,showed that multileveled layers structure not only decreasing the drop pressure but also bettering filtration efficiency.3.Study on necklace like structured PA6-PS nanofibrous membranes.The necklace-like structured nanofibers were fabricated from polyamide 6(PA6)embedding polystyrene(PS)microspheres via electrospinning.The PS microspheres were synthesized by a polymerization of styrene with AIBN and PVP in the PA6 solution at 70?.Then the morphology of the necklace-like fibers,the diameter of PS microspheres,the weight ratio of PA6 to styrene were investigated systemically.With the concentration of styrene 1.0 m L to 28 wt%PA6 solutions and the amount of 0.05 g AIBN and 0.3 g PVP,the diameter of PS microspheres was attended 228nm,and the microspheres of PS tended to align along the fiber one by one.The BET surface area is7.516 cm²g^-1,whose is larger than smooth surface membranes.The results for necklace-like nanofiber mats performed on DOP aerosol particles filtration suggested that the necklace-like membrane of 1.5 h spinning time had good filtration performance with a low pressure drop 160Pa,and a high filtration efficiency 96.65%,which were better than pure PA6 membrane under the same face velocity.