Preparation Of Nanofiber-based PM2.5 Filter Media Based On Water-soluble Polymer PVA Membrane Modified By Crosslinking

At present,high-efficiency and ultra-high-efficiency air filter materials for antihaze are generally prepared by electrostatic electret melt-blown nonwoven fabrics and electrospinning nanofiber materials.But the filtering effect of electrostatic electret melt-blown nonwoven fabrics will change with ambient temperature and humidity which would cause unstable filtering effects,and static electricity will cause some harm to the human body.Electrospinning nanofiber membranes have been commercialized for industrial gas filtration due to their large specific surface area,high porosity,and ease of preparation.However,water-insoluble polymers involve the collection and recycling of organic solvents in the electrospinning process.And it will cause environmental pollution or increase costs.The electrospinning membrane made by water-soluble polymer is environmentally friendly,non-toxic and biodegradable.It is a good choice for the preparation of air filter materials,especially the PM2.5 respirator.However,the water-soluble polymer contains a large number of hydroxyl groups that are easily hydrolyzed or swelled in a humid environment,resulting in extremely unstable filtration efficiency.Therefore,it needs to be subjected to hydrolysis modification treatment.In view of the existing problems of air filter materials,water-soluble PVA was modified with PAA,GA,and SS,respectively,to improve the resistance to hydrolysis and wet swelling.In this paper,PVA/PAA,PVA/GA and PVA/SS blended modified electrospinning membrane were prepared by multi-needle electrospinning technology.After thermal cross-linking,they were combined with traditional nonwovens.The morphology,structure,filtration performance and hydrolysis resistance of the electrospinning membranes and their composite filters were characterized.It was found that the nanofiber diameter and diameter distributions of PVA/PAA,PVA/GA,and PVA/SS blended modified electrospinning membranes in the optimum process parameters were 181.66nm/15.61%,116.99nm/15.09% and 168.43 nm/16.02%.The pore size distributions were 501.7.07 nm to 1072.3 nm(average pore size 951.7 nm),233 nm to 692.7 nm(average pore size 527 nm),and 378.1nm to 742.1 nm(average pore size 689.7 nm),respectively.The filtration efficiency and filtration resistance was 99.477%/88 Pa,99.166%/90 Pa,and 98.607%/85 Pa,respectively.At the optimum heat treatment temperature of 160°C,the three kinds of PVA cross-linked modified electrospinning membranes were immersed in water at 85°C for 3 hours and the weight loss rates of hot water were 0.13%,0% and 3.65%,respectively.Then they were soaked in water at room temperature for 3 hours,and the weight loss rate is 0%.The PVA nanofiber composite filter material developed in this project has the characteristics of environmental protection,non-toxicity,high filtration efficiency,low filtration resistance,hydrolysis resistance and swelling resistance.And it can be used for personal care such as PM2.5 protection,virus protection,pollen protection,and dust protection,and medical protection,labor protection,industrial gas filtration,engine gas filtration,clean room air filtration,air purifiers,indoor fresh air systems,and high-end air filter materials such as flood screens.