Study On Preparation And Properties Of Antibacterial Polypropylene Nonwovens Containing N-halamine Structure

In an era of intermittent outbreaks of airborne pathogens,the general public and medical personnel urgently need protective equipment to prevent pathogen infection when going out or working in the environment.Polypropylene medical protective masks are currently the primary measure for people to resist the invasion of air-borne pathogens,and the polypropylene melt-blown nonwoven materials,which plays the main filtering role,can use the dense three-dimensional disordered fiber structure inside to block the external pathogens.However,due to the lack of polypropylene bactericidal function,the pathogens blocked in the polypropylene melt-blown nonwoven materials still survive,and improper handling after use will cause infection to the human body.Therefore,it is significant to inactivate pathogens in polypropylene nonwoven materials.In this paper,halogen-based antibacterial agents are used to modify polypropylene to give polypropylene nonwoven materials antibacterial functions.This paper is mainly divided into the following three contents:(1)Using reaction extrusion technology,halogen precursor methyl acrylamide(MAM)is grafted to the polypropylene(PP)main chain through free radical grafting to prepare modified polypropylene grafted methyl acrylamide(PP-g-MAM)masterbatches,and PP-g-MAM antibacterial melt-blown nonwoven materials is prepared by melt-spinning process,electrostatic electret treatment and chlorination treatment.Finally,the composition structure,thermal weight loss behavior,mechanical properties,surface morphology,filtration effect,active chlorine content and antibacterial properties of PP-g-MAM melt-blown nonwoven materials are comprehensively evaluated.The results show that the grafting of MAM has no effect on the mechanical properties and surface morphology of polypropylene melt-blown nonwoven materials;due to the chlorine treatment process,the static charge in the nonwoven materials will be lost,and the filtration performance of the nonwoven materials will be greatly reduced,but the filtration performance of the nonwoven materials can be restored by re-electrostatic precipitation;the active chlorine content in the chlorinated PP-g-MAM melt-blown nonwoven materials is up to 403 ppm,and it has good antibacterial effect on Escherichia coli and Staphylococcus aureus.(2)Polypropylene-grafted-1-allylhydrazine(PP-g-AHD)was prepared by free radical melt grafting copolymerization,and then PP-g-AHD antibacterial nonwoven materials were prepared by melt electrospinning and chlorination treatment.In the experiment,polypropylene resin was used as raw material to explore the effects of spinning temperature,spinning voltage,collecting distance and collecting mode on the diameter and distribution state of polypropylene fibers,and then the PP-g-AHD polymer was made into nonwoven materials on this basis.Fourier infrared spectroscopy,organic element analyzer and scanning electron microscopy were used to test the polypropylene fibers and PP-g-AHD nonwoven materials.The results showed that the diameter of polypropylene fibers prepared by melt electrospinning was between 2 and 11 μm,the minimum average diameter of fibers in PP-g-AHD nonwoven materials was 8.43 μm,and the fibers were interlaced and evenly distributed;After chlorination,the active chlorine content of PP-g-AHD nonwoven material exceeds 200 ppm.The antibacterial rate of chlorinated PP-g-AHD nonwovens was more than99% after contact with Escherichia coli and Staphylococcus aureus for 30 minutes.(3)Incorporation of halamine-containing nanoparticles into polypropylene melt-blown nonwoven materials was achieved through UV irradiation on the surface of the material.Poly(MAM-MBA)halamine nanoparticles were formed on the surface of the polypropylene melt-blown nonwoven fibers through cross-linking reaction between functional monomer,methyl acrylamide(MAM),and cross-linking agent,N,N’-methylenebis(acrylamide)(MBA),providing the nonwoven material with antimicrobial properties and increased hydrophilicity.The influence of different monomer concentrations,cross-linking agent concentrations,photoinitiator concentrations,and UV irradiation times on the content of P(MAM-MBA)nanoparticles embedded in the nonwoven material was studied.The effect of different chlorination conditions on the active chlorine content of PP-P(MAM-MBA)nonwoven materials was explored.Fourier transform infrared spectrometer,X-ray photoelectron spectrometer,and energy-dispersive spectrometer were used to analyze the nanoparticles on the surface of the polypropylene melt-blown nonwoven material.Scanning electron microscopy,contact angle meter,Instron electronic tensile tester,fabric air permeability tester,and filter comprehensive performance tester were used to characterize the surface morphology,hydrophilicity/hydrophobicity,mechanical properties,air permeability,and filtration performance of PP-P(MAM-MBA)nonwoven material.The PP-P(MAM-MBA)nonwoven material fibers showed obvious particle formation on their surface and a significant improvement in hydrophilicity.The longer the UV modification time,the more P(MAM-MBA)nanoparticles were present on the surface of the modified polypropylene nonwoven material.However,while the content of P(MAM-MBA)nanoparticles increased,the air permeability of the PP-P(MAM-MBA)nonwoven material decreased significantly.Under the conditions of 15% MAM concentration,3% MBA concentration,1% BP concentration,and 5 minutes of UV irradiation,the PP-P(MAM-MBA)-Cl nonwoven material produced had an active chlorine content exceeding 3500 ppm after chlorination.In antibacterial testing,PP-P(MAM-MBA)-Cl nonwoven material showed high antibacterial effect on Escherichia coli and Staphylococcus aureus.