Study On Preparation, Structure And Properties Of Silver Loading Zeolite 4A Antibacterial Agents And Silver And Zinc Loading Nano-SiO₂ Antibacterial Fibres

With the development of society and improvement of standard of living, the healthy living environment has increasingly become the goal of human beings in life. Bacteria are attracting more and more attention owing to their harm to our living environment Therefore, it is significant to restrain the growth and propagation of harmful bacteria, protect human beings' health and decrease disease using antibacterial materials. Ag-containing inorganic antibacterial agents have become a focus in the research and application field of inorganic antibacterial materials because of safety, durability, heat resistance, long lasting, stability, and broad-spectrum antibacterial activity.In this paper, the silver-loading zeolite 4A antibacterial agent (ZLS) was prepared by ion exchange method with zeolite 4A as the carrier and AgNO₃ solution as exchange solution. The preparation process was discussed in detail. The heat resistant property of ZLS was thoroughly investigated by heat treatment methodology. A method was given to enhance color change resistance by increasing the content of zinc and reducing that of silver in silver and zinc-loading zeolite 4A antibacterial agent (ZLSZ).The antibacterial wool fiber was obtained by grafting silver and zinc-loading Nano-SiO₂ antibacterial agent (SLSZ). The mechanism of modification of wool fiber by ultraviolet radiation was primaril discussed, while the grafting mechanism of SLSZ on the wool fiber surface was deeply investigated. The antibacterial PET masterbatch was extruded from twin screw extruder, the modification of SLSZ by silane coupling agent was investigated, and the antibacterial characteristics of antibacterial PET masterbatch was discussed. The antibacterial PETPOY fiber was spun by high-speed melt-spinning method. Moreover, the influences of spinning technics and the amount of antibacterial PET masterbatch on the spinnability of antibacterial PETPOY fiber were systematically investigated as well.The morphologies of the samples were observed by Scanning Electron Microscopy (SEM). The structures of specimens were characterized by High-Resolution Transmission Electron Microscopy (HRTEM), X-ray diffraction (XRD), and Infrared Radiation spectrum (IR). The contents of silver and zinc were measured with Inductively Coupled Plasma Spectrometer (ICPS). The antibacterial properties of all specimens were tested using alive-bacteria-counting, Minimum Inhibitory Concentration method (MIC), or flask-shaking method.The main conclusions are as follows: (1)The optimum parameters for the preparation of ZLS are: the concentration of AgNO₃ solution of 0.1mol/L, the pH value between 6～8, the temperature of 50℃, and the reaction time of 4h. The structure of zeolite 4A showed no change after exchange reaction with silver ions. ZLS had an excellent antibacterial performance against E.coli and S. faecalis. The antibacterial effects of ZLS against E. coli and S. faecalis were different because of the structural difference between the bacteria. Also, the antibacterial properties of ZLS were enhanced with increasing dose of the antibacterial agents and prolonging contact time.(2)As heat treatment temperature increased the particle size increased, more aggregating occurred, silver content decreased, the colour of ZLS gradually changed from white to brown, and the antibacterial ability weakened. The release rate of Ag⁺ cation from ZLS became slow after heat treatment at 400℃, 450℃and 500℃, thus resulting in prolonged service life of ZLS. When the heat treatment temperature approached 850℃, the porous structure of ZLS was destroyed, and the crystals of SiO₂ and Al₂O₃ were formed after recrystallization. Consequently, the heat resistant temperature ofZLS can be as high as 500℃.(3) ZLSZ had excellent antibacterial performance and color change resistant property.(4)Nano-SiO₂ can be used as a carrier to prepare inorganic antibacterial materials by adsorption. The structure of the nano-SiO₂ had no change after absorbing silver and zinc cations. SLZS exhibited similar antibacterial properties as ZLS, but the antibacterial effect of SLZS was better than that of SLS.(5)The antibacterial layer was formed by covalent bonding between SLZS and wool fiber under ultraviolet radiation. The antibacterial wool fiber showed excellent antibacterial performance and wash resistant property. In other words, the antibacterial rate was higher than 90% after repeated wash (at least 20 times).(6)The optimum parameters for the surface modification of SLSZ were: the temperature of 60℃, reaction time of 1.5h, the pH value of 10, and the concentration of silane coupling agent of 4% (wt).(7)When the content of SLSZ was 30%(wt), SLSZ was stably distributed in the antibacterial PET matrix, whit the morphology of irregular spheres and the averaged particle size of 150nm. Antibacterial PET masterbaches had strong sorption to E.coli, and with the increase of the dose of the masterbach, the adsorption speed became faster and the adsorption content became larger.(8)The antibacterial PETPOY fiber was spun by high-speed melt-spinning method. The optimum spinning conditions of the antibacterial PETPOY fiber were: the temperatures from Zone through 5 were 5-10℃lower than for pure PET, the temperature of spinning box was 286℃, the oiling rate was 0.75%, the speed of side wind was 0.35-0.4m/s with the temperature of 14℃, and the content of antibacterial PET masterbach was 6%. The antibacterial PETPOY fiber exhibited excellent mechanical, antibacterial and wash resistant properties.