Controllable Preparation Of PSU-based Electret Nanofiber Air Filter Material And Its Application In Vehicle Air Purifier

Air is a necessary condition for human beings to survive.In recent years,with the rapid advancement of the industrialization,it has brought rapid development to the economy.But at the same time,it has also brought serious air pollution problems,which seriously endangers human health.Meanwhile,with the improvement of people's life standards,more and more cars have become the primary transportation for people,and people have more time to stay in the car.With the gradual deterioration of the atmospheric environment,the indoor environment of the car will also become bad.And in the meantime,some of the car's decoration,fabrics and etc will also release harmful substances,making the car internal environment even worse.The car air purifier,as a tool for air purification,can purify the air inside the car quickly and effectively under the power drive.The air pollutants in the car are mainly divided into two categories:fine particles and VOCs gas.At present,the core materials of the purifying filter of the vehicle air purifier are mostly ordinary non-woven fiber filter materials,glass fiber filter materials and melt-blown fiber filter materials.However,the ordinary non-woven filter material can achieve effective filtration of particulate matter,but the fiber diameter is difficult to meet the high-precision filtration of fine particles;the glass fiber filter material can achieve higher filtration efficiency by virtue of the fine diameter and small pore diameter,but there is a problem of high air resistance;the melt-blown electret filter material can achieve high filtration performance without increasing the piezo resistance,but its stability is greatly affected by the environment and the life cycle is short.Therefore,air filter materials now have the drawback that air filtration efficiency and air resistance cannot be balanced,which means high efficiency and low resistance cannot be achieved,and most of the materials are single functional materials,mainly for fine particle contaminants,and simultaneously it is impossible to effectively filter the PM2.5 particles in the internal environment or purify harmful substances such as formaldehyde released by leather,which cannot meet the demand for car air purifier materials.So it is urgent to develop air filter material with high efficiency,low air resistance and formaldehyde removal function.The fiber electret technology can store a large amount of electric charge in the filter material,and have the high-efficiency adsorption of the fine particles by electrostatic action which expected to achieve the balance of filtration efficiency and the air resistance existing in the current fiber air filter material.Most of the current electret materials are fiber-added and then added with electrostatic electret.This electret mode has the problem of storing low charge and instability.However,the electrospinning technology can inject charge in situ during fiber formation,so that the fiber charge can be stably formed after molding,greatly enhance the electret performance of the material,and have fine fiber diameter and high porosity,which help to achieve high filtration efficiency and low air resistance.In addition,in the electrospinning process,the function of the material can be diversified by introducing a functional additive into the electrospinning stock solution.On the basis of electrospinning technology,our work obtained different PSU solutions by adjusting the PSU content concentration and spinning humidity environment of organic electret materials,and spinning different PSU solutions into electret nanofiber membrane materials.Meanwhile the filtration performance and morphological structures such as fiber diameter,pore size and porosity of the fiber membrane were characterized by scanning electron microscopy?SEM?,bubble point pore size analyzer?PMI?and comprehensive filter tester?LZC-H?.And we calculated the fiber membrane charge and system explored the charge storage performance and stability by the non-contact electrostatic probe test.At last,the result determined that the spun fiber membrane has optimum air filtration performance and electret stability at the condition of the PSU content of 22wt%and the humidity of 43±4%.The filtration efficiency of the fiber membrane can reach above 99%,and the charge is stably stored.In order to further improve the filtration performance of PSU electret nanofiber membranes to harmful gases,the MnO₂,as a formaldehyde removal agent,was added and regulated.The effects of different contents of MnO₂ on fiber morphology and fiber membrane properties were investigated,and finally confirmed that an optimum content of the MnO₂ is 1 wt%.While maintaining the efficiency of 94.8%,the fiber membrane can also achieve efficient decomposition and removal of formaldehyde.The scale preparation of PSU composite fiber membrane is completed,and the PSU composite fiber membrane is processed and applied to the vehicle purifier filter.After the actual test,the formaldehyde removal efficiency of the filter cartridge can be stably achieved to 90%,and the filtration efficiency reaches 98%.Low pressure resistance and long-term service life have good application prospects in the field of air purification.