Study On The Preparation, Performance And Application On PVC Of ZnO/Ag Nano-Composite Antimicrobial Agent

In this paper, we studied on the preparation, properties and application on PVC of ZnO/Ag nano-composite antibacterial agent.1. The precursors of ZnO/Ag Nano-composite antimicrobials were synthesized by the two-step precipitation method with ZnSO4 and AgNO3 as the starting material and NH4HCO3 as the precipitation, and then the ZnO/Ag nano-composite antibacterial agents were prepared by centrifuge, drying and calcination of the precursors. The morphology, structure, particle dispersion of products and thermal decomposition process of precursors were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), laser particle size distribution and thermal gravimetric (TG-DTG), The effects of the synthesis temperature and reaction time on the morphology of the ZnO/Ag Nano-composite antimicrobial precursors and products were studied, while the influence of drying method, washing method and dropping velocity of precipitation on the morphology of products were explored. According to the TG-DTG data with different heating rates and the commonly seen solid state thermal composition reaction kinetic equation, the thermal decomposition kinetics suitable for this reaction were identified, then the E and A were calculated, while the heating rate of calcined process was obtain, the influence of calcination temperature and the holding time on morphology and structure of final products that obtained in air and vacuum were studied respectively. The optimum process conditions of high quality ZnO/Ag nano-composite antimicrobial (containing silver 10%) were obtained as follow:(1) Technology of precursors synthesis: using mechanical agitation, with 3 mL/min dropping velocity of precipitation, the reaction temperature is 20℃~25℃(at room temperature generally), the reaction time of ZnSO4, AgNO3 and NH4HCO3 is 2~3h.(2) Technology of the precursor post-processing: using centrifugal washing, washing twice with distilled water and twice with ethanol respectively, and then drying it in 30℃vacuum atmosphere for 12 hours. (3) Technology of the precursor calcination: air or vacuum calcination atmosphere, heating rate is 10 K / min, calcination temperature is 400℃~450℃, and the holding time is 3~4 h.Basis on above conclusion, the containing silver 5%, 15%of ZnO/Ag nano composite antibacterial agents were prepared by changing the amount of AgNO3, the scientific basis of ZnO/Ag nano-composite antibacterial agent's industrial production was provided.2. Commissioning the Guangzhou detection center of microbiology analysis the antibacterial performance of ZnO/Ag nano-composite antibacterial agent, the results were showed as follow:(1) Antibacterial performance of ZnO/Ag nano-composite antibacterial agent (Containing silver 5%): the Escherichia coli antibacterial rate of the agents that sintered in vacuum is 99.98% and the Staphylococcus aureus antibacterial rate is 99.96%; the Escherichia coli antibacterial rate of the agents that sintered in air is 99.98% and the Staphylococcus aureus antibacterial rate is 99.93%.(2) Antibacterial performance of ZnO/Ag nano-composite antibacterial agent (Containing silver 10%): the minimum inhibitory concentrations of the Escherichia coli and Staphylococcus aureus by the agents that sintered in vacuum and air are 50 mg/L.(3) Antibacterial performance of ZnO/Ag nano-composite antibacterial agent (Containing silver 15%): the Escherichia coli antibacterial rate of the agents that sintered in vacuum is 99.98% and the Staphylococcus aureus antibacterial rate is 99.96%; the Escherichia coli antibacterial rate of the agents that sintered in air is 99.98% and the Staphylococcus aureus antibacterial rate is 99.95%.3. The ZnO/Ag nano-antibacterial agent was modified by titanium coupling agent, and the antibacterial PVC nano-composites can be obtained via mixing and pressuring the antibacterial agent and PVC ingredients. The former and latter of modified nano-particle's morphology and decentralized state were characterized by sedimentation testing, laser particle size distribution testing and the images of TEM; the surface morphologies of antimicrobial PVC and ordinary PVC were studied by the images of SEM; according to the Quinn experiment of disinfection technical specifications, the antibacterial properties of antimicrobial PVC were discussed; according to the GB/T1040-92 standards, the mechanical properties of the sample affected on nano-antibacterial agent addition were researched. The result verifies that:(1) The sedimentation rate of ZnO/Ag nano-antibacterial agent decreased from 0.94 to 0.004 after modified, its lipophilic and stability were enhanced greatly, the size of product modified by titanium coupling agent distributes from 20nm to 40nm, and the decentralized state of antibacterial agents were meliorated excellent. (2) The ZnO/Ag particles of antibacterial PVC dispersed in nano-scale were showed by SEM images, the ZnO/Ag nano-particles not only played the effectiveness of antibacterial, but also with dispersion-strengthened role.(3) The Escherichia coli antibacterial rate of antibacterial PVC reaches over 99%, and the antibacterial rate will enhance with adding antibacterial agents.(4) The tensile strength and elongation at break of antibacterial PVC could increase at first and then declined with adding antibacterial agents, when the ZnO/Ag nano-antibacterial agent is added 2g (1.5%), the tensile strength and elongation at break are reached the maximum—43.67 Mpa and 195% respectively, and then the ZnO/Ag nano-antibacterial agent is added 4g (3%), the tensile strength and elongation at break approach initial value.