Preparating Of Supported Antibacterial Agents And Its Application In Polypropylene

With the development of science and improvement of people's environmental awareness, the healthy living environment has increasingly become the goal of human beings. Germs are absent nowhere, and many of them can cause diseases and menace the health of mankind, which has attracted closest attention. Antibacterial materials can effectively inhibit the growth and reproduction of bacteria, which is significant to protect human beings'health when applied in daily life.In this dissert, zinc-exchanged montmorillonite was firstly prepared by an ion exchange method, and then a novel antibacterial composite of zinc pyrithione/montm- orillonite was in situ prepared by introducing pyrithione anion into the galleries of zinc-exchanged montmorillonite. Preparation technology, antibacterial activity, light and thermal stability of this complex antibacterial agent were systematically investigated. Additionally, antibacterial masterbatches containing polypropylene and zinc pyrithione/montmorillonite (modified by silane coupling agent) were prepared by a twin screw extruder. Then the antibacterial polypropylene was prepared by mixing the above antibacterial masterbatches with pristine polypropylene resin. The dispersion of antibacterial agent in the matrix resin, the influence of antibacterial concentration on the antibacterial property, processability, crystallization property and mechanical property of the antibacterial polypropylene were studied. The main conclusions drawn from the systematical investigation are as follows:The optimum conditions for the preparation of zinc-exchanged montmorillonite are: the ratio of solid to liquid is 1:10, the concentration of Zn(NO3)2 solution is 0.10mol/L, the reaction time is 4h, the temperature is 70℃and the pH value is 5. The optimum conditions for the preparation of zinc pyrithione/montmorillonite are: the solvent is dimethylsulfoxide, the ratio of solid to liquid is 1:10, the concentration of pyrithione anion is 0.20mol/L, the reaction time is 3h, the temperature is 65℃and the pH value is 4. The results of X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) show that zinc pyrithione exists as the form of monolayer horizontal orientation between layers. The results of TG, DSC and UV-Vis DRS indicate that the zinc pyrithione/montmorillonite has a favorable light and thermal stability. Moreover, antibacterial experiment results show that the zinc pyrithione/montmorillonite possesses an excellent antibacterial activity and sustained release property.The optimum conditions for the preparation of antibacterial polypropylene are: the content of zinc pyrithione/montmorillonite in the antibacterial masterbatches is 20wt%, the amount of adding antibacterial masterbatches is 5wt%. The observations of SEM and TEM suggest that pyrithione/montmorillonite particles are dispersed uniformly in the matrix. The results of XRD demonstrate that the main crystalline form of antibacterial polypropylene isαcrystal, coexisting with minorβcrystal induced by antibacterial materials. Meanwhile, the montmorillonite layers in the poly- propylene were not exfoliated. The pyrithione/montmorillonite has a heterogeneous nucleation effect on the crystallization of polypropylene, causing the number of crystal nucleus increase dramatically while their dimensions were decreased. Furthermore, the existence of antibacterial agent results in the increase of crystallinity, crystallization peak temperature and crystallization rate, but the melting peak temperature remains the similar value. The results of mechanical properties test indicate that the flexural modulus and impact strength are enhanced whereas the tensile strength slightly declined when the content of antibacterial masterbatches in antibacterial polypropylene is 0~6wt%. Besides, the processing viscosity decreased after adding antibacterial masterbatches. The results of antibacterial experiment demonstrate that the antibacterial polypropylene has excellent antibacterial activity (their antibacterial rates are all above 99% against E.coli and S.aureus) when the amount of masterbatches added is 5wt%, and it also possesses good antibacterial durability.