Preparation, characterization, antimicrobial and cytotoxicity studies of copper/zincloaded montmorillonite

Background： A series of modified montmorillonites（Mt） including zinc-loaded Mt（Zn-Mt）, copper-loaded Mt（Cu-Mt）, copper/zinc-loaded Mt with different Cu/Zn ratio（Cu/Zn-Mt-1, Cu/Zn-Mt-2, Cu/Zn-Mt-3） were prepared by an ion-exchange reaction, and characterized using X-ray diffraction（XRD）, fourier transformed infrared spectroscopy（FTIR） and transmission electron microscopy（TEM）. The specific surface areas, antimicrobial activity and cytotoxicity of the modified Mt were investigated.Results： In the modified Mt, hydrated Cu ions and Zn ions were exchanged in the interlayer space of Mt and the particles were irregular shapes. The results showed that Cu/Zn-Mt enhanced antibacterial and antifungal activity compared with Zn-Mt and Cu-Mt possibly due to the synergistic effect between Cu and Zn. Among the Cu/Zn-Mt with different Cu/Zn raitos, Cu/Zn-Mt with a Cu/Zn ratio of 0.98 or 0.51 showed higher antimicrobial activity against gram-negative bacteria（Escherichia coli）, gram-positive bacteria（Staphylococcus aureus）, fungi（Candida albicans）.Moreover, the antimicrobial activity of Cu/Zn-Mt was correlated with its specific surface area. Cytotoxicity studies on IPEC-J2 cell showed a slight cytotoxicity of Cu/Zn-Mt.Conclusions： The current data provide clear evidence that in terms of its antimicrobial activity and relatively low toxicity, the Cu/Zn-Mt holds great promise for applications in animal husbandry.

STUDIES ON COMBUSTION BEHAVIOR OF NR/MMT NANO-COMPOSITES BY CONE CALORIMETER

The NR/modified montmorillonite （EMT） nano-composites were prepared by mechanical mixing and reacting in situ with glycidyl methacrylate. Under 30 kW·m^-2 of heat flux, the combustion behavior of the nano-composites was studied with cone calorimetry, and PHRR, THR, EHC, TSR and MLR were tested. The results showed that the nanocomposite had improved mechanical properties and flame retardance properties, and to some extent, the nano-composite had smoke suppress effect. Compared with pure NR, the PHRR, EHC and SPR of the nano-composite reduced by 34%, 21% and 16.8%, respectively.

Preparation,characterization and performance of poly(m-phenylene isophthalamide)/organically modified montmorillonite nanocomposite membranes in removal of perfluorooctane sulfonate

Nanocomposite membranes containing poly（m-phenylene isophthalamide）（PMIA） and organically modified montmorillonite（OMMT） were prepared by a combination of solution dispersion and wet-phase inversion methods, and the effects of OMMT addition on the properties and performance of fabricated nanofiltration membranes were investigated. The membranes were characterized by contact angle measurements, scanning electron microscopy（SEM）, atomic force microscopy（AFM）, thermogravimetric analysis, and zeta potential.The performance of the membranes was elucidated by the removal of perfluorooctane sulfonate（PFOS） at neutral p H. Increasing OMMT concentration improved the thermal stability and hydrophilicity of the membranes. The permeation and rejection of PFOS were significantly improved. The performance of fabricated nanofiltration membranes in removal of PFOS varied depending on the solute and membrane properties as well as solution conditions. Finally,a comparison between fabricated membranes and a commercial NF membrane（ESNA1-K1,Hydecanme） proved that the OMMT addition is a convenient procedure for producing nanocomposite membranes with superior properties and performance.

Effect of Surface-modified Clay on the Thermal Stability and Insulation of Polyorganosiloxane Foam

Polyorganosiloxane foam（SIF） nanocomposites reinforced with vinyl-modified montmorillonite（Mt-V） and hydroxyl-modified montmorillonite（Mt-OH） were prepared through cross-linking and foaming. The effects of modified Mt on the density, pore morphology, and thermal and compressive properties of the prepared polyorganosiloxane foams were investigated. The structure of the polyorganosiloxane foam was studied by solid-state nuclear magnetic resonance analysis. Clay dispersion in polyorganosiloxane nanocomposites and pore morphology were in- vestigated by X-ray diffraction and scanning electron microscopy analyses. The thermal and mechanical properties of the prepared materials were also evaluated by differential scanning calorimeter, thermogravimetric analysis, thermal diffusivity and compressive strength. The results show that Mt-V exhibits improved cell structure, thermal insulation, and crush compressive than Mr-OH. The addition of modified Mt reduces the density, cell size, and thermal conduc- tivity but increases the high-temperature resistance and compressive strength of the nanocomposite. The amount of the residues of SIF/Mt-OH nanocomposites increases by 9% compared with that of the pure SIF. Furthermore, SIF/Mt-V decreases the thermal conductivity to 0.014 W/mK and the cell size to 98μm. Those properties give the material potential application value in the aerospace and construction industry.