Study On Preparation And Property Of PAN/TiO₂ Micro-Nanofiber Nonwoven Via Electrospinning

With the development of industrialization,the problem of air pollution in China was becoming more and more serious,due to the PM 2.5 severe weather,the respiratory infection,the decline of resistance and other problems were also common.PM 2.5 were the particles with diameters of less than 2.5μm.Nanofibers made by electronic spinning owned fibers whose diameters are between sub-micron and nanometer.That ensured they have the unique advantages to prevent dust haze with high ratio surface area and porosity.Therefore,Polyacrylonitrile/titanium dioxide（PAN/TiO₂）micro-nanofiber nonwoven was prepared by two-step method.And the properties of the micro-nanofiber nonwoven should be tested.First of all,in order to increase the fiber diffusion effect and interception effect,the paper studied a way to improve the fiber specific surface area.Then the PAN/TiO₂ micro-nanofiber nonwoven was developed.It was found that when the mass concentration of PAN was 10%,the nonwoven owned the better morphology.As the basic of 10%mass concentration of PAN,with the mass concentration of TiO₂ increased,the viscosity of the solution was decreased.And the diameter of PAN/TiO₂ micro-nanofiber nonwoven was decreased too,with the uneven state appearing upon the fibers.When the concentration of TiO₂ increased from 1.5 wt%to 0 wt%,the roughness of the fiber increased from 0.77μm to 2.81μm.However,when mass concentration of TiO₂ was 2.0%,the roughness remained at 2.62μm because of the agglomeration phenomenon.Secondly,the paper tested and studied the properties of the PAN/TiO₂ micro-nanofiber nonwoven.As a result,with the mass concentration of 1.5%,the specific surface area of PAN/TiO₂micro-nanofiber nonwoven was three times more than the PAN micro-nanofiber nonwoven with19.0054 m²·g^-1.As for the filtration performance,the impact factor was up to 0.02651 Pa^-1.However,at the same time,the strength performance of PAN/TiO₂ micro-nanofiber nonwoven was also reduced.And the antibacterial rate effect towards escherichia coli and staphylococcus aureus was up to 98.99%and 93.60%respectively.In order to solve the weakness strength performance of PAN/TiO₂ micro-nanofiber nonwoven.The paper proposed a graded and composite fiber structure.And through the Comsol software and computational fluid dynamics CFD simulation to construct uniform fiber diameter structure model and mixed fiber diameter structure model.With the simulation,the pressure drop of mixed fiber diameter structure was lower than the other one which provided theory basis for the practical experiment in the next part.Finally,as the basis of 1.5 wt%TiO_2,10 wt%PAN-DMF-1.5 wt%TiO₂（10%PAN/TiO₂）was then composited to 14 wt%PAN-DMF-1.5 wt%TiO₂（14%PAN/TiO₂）by electrospinning under different blend ratios.The main properties of graded micro-nanofiber nonwoven were:pore diameter and pore size distribution,mechanical property,filtration property and dust retention capacity.It was obtained that when the blend ratios was 1:2,the quality factor of graded micro-nanofiber nonwoven was up to 0.02856 Pa^-1.The pressure drop was decreased to 110 Pa with the efficiency was 95.68%.The mechanical property and dust retention capacity of the graded micro-nanofiber nonwoven were better also.