| Serious impact on human life and health due to the serious fog and haze in recent years, the development of a new filter material is imminent as the filtering effect of PM2.5 of most conventional anti-fog and haze masks is not good, since polymer microporous membrane was widely used in filtration technology, this topic will be expanded from the point of microporous membrane filtering PM2.5 particles.A new type of air filter material anti PM2.5 was studied based on the recent haze issue as a starting point. As the research materials, WBPU and PVA were mixed in different proportions, as well as used different substrates and porogens, to explore the best process of forming coating microporous membrane by solvent-nonsolvent method, then, it was given anti-bacterial and anti-UV properties by adding functional nanomaterial, finally, WBPU/PVA composite microporous membrane was successfully prepared and applied to the air filter material.The main research work and results are as follows:(1) First, results showed that WBPU/PVA have good compatibility, it can be mixed in any proportion by taken IR spectroscopic characterization, which provided a feasibility study to their complex. And then it was found the thermal properties, mechanical properties, water resistance were complicated, almost between the two components alone by the characterization of different proportions of WBPU/PVA films. More over, DMF as solvent, water as nonsolvent, urea as porogen, solvent-nonsolvent dry/wet method was used to prepared WBPU/PVA composite microporous membrane successfully. SEM images showed pure WBPU microporous membrane is not conducive to filter PM2.5 particles for its’ thin structure and large aperture, and PVA was helpful to generate a layer and multi-dimensional mesh structure, however, excess PVA can cause the the pores reduced or even disaooear in the composite membrane, at last, it was explored the composite ratio of WBPU and PVA to achieve the best composite microporous membrane is 0.8/0.2 preliminary. In addition, the adding of AgI complexing agent improved antibacterial and UV performance effectively.(2) Films formed on the surface of the substrate by coating in this paper, and finally, the substrate is selected as the water-repellent polypropylene spunbond 40g/m2 non-woven fabric. A large amount of factors affected the film-forming process, although solvent-nonsolvent wet film formation method is simple and easy, therefore, this issue sifted the main factors by single-factor control method, finally get the best process recipe as follows: WBPU/PVA blend ratio is 0.8/0.2, polymer concentration is 14%, 8% urea as the porogen, the concentration of DMF coagulation bath is 20%, pre-drying time(at room temperature) is 2h, soaking time in coagulation is 8min, soaking 24~36h in 25℃ pure water, natural drying(25℃ is best),in order to form a more suitable pore size and structure, butanone can be complexed with DMF, and the optimal complex ratio is 0.5/1.(3) Under the WBPU/PVA mixing ratio of 0.8/0.2, the composite coating film improved water-repellent properties of the coated fabric, as the hydrogen solid bonded WBPU with PVA, thus made a low water-soluble loss rate and good stability. In this proportion, the mechanical strength of the coating fabric is significantly better than the blank sample as well as the samples at other ratios. Anti-pollution tests showed that the adsorption capacity of sericin has decreased significantly than the blank sample, it had a certain resistance to pollution obviously.SEM images showed nano-AgI complexing agent not only didn’t change the filming and porogenic process, but also gave good antibacterial and anti-UV properties. Anti-bacterial test showed the inhibition rate as high as 97.8%, UV test found that UV transmittance of the sample with AgI was far below the sample without Ag I, and with the addition of AgI, the UPF index of single and double layers samples reached 19.86, 92.91 respectively. |
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