Fe saponite, a layered silicate for reversible lithium-ions storage with large diffusion coefficient

A kind of layered Li;MSiO;material,Fe saponite with Na;pillaring (Na^(+)-FSAP) was developed as a lowcost and environment-friendly lithium-ion storage material.The Na^(+)-FSAP follows the insertion/deinsertion working mechanism accompanied by valence change of Fe from Fe^(1.86+) to Fe^(2.71+) (average value) after stabilization,and displays a specific capacity of 125 m Ah g^(-1) at 50 m A g^(-1) with retention ratio of 80.8%after 75 cycles.The Na^(+)-pillaring effect and abundant structural water in the gallery urge Li^(+) migrate rapidly,resulting in a large Li^(+) diffusion coefficient within a range of 10^(-6.5)–10^(-7.5) cm^(2)s^(-1).Thus,the Na^(+)-FSAP provides a model material to design electrode materials with rapid lithium-ion migration and has great potential to take place of polyanionic-type Li_(2)MSiO_(4)(M=Mn,Fe,Co) cathode materials.

DISPERSION AND NUCLEATION FOR ULTRAFINE PARTICLES OF SILICA AND SILICATE IN POLY(ETHYLENE TEREPHTHALATE) BASED COMPOSITES

In this paper, the dispersion and nucleation behavior of ultrafine particles of silica and layered silicate (LS) in poly(ethylene terephthalate) (PET) matrix are investigated and characterized by Transmission Electron Microscopy (TEM), Wide Angle X-ray Diffraction (WAXD), Dynamic Scanning Calorimetry (DSC), and Atomic Force Microscopy (AFM). The solid precursors based on silica and LS are suggested originally for preparing nanocomposites with good dispersion morphology. Results show that the initial sub-micron (1000~500 nm) LS particles are exfoliated or dispersed into nanometer-scale particles (30~70 nm) during their polymerization with PET monomers. These dispersed nanoparti-cles form an ordered morphology in their nucleation and growth during annealing nanocomposites. DSC patterns reveal that the double melting peaks of annealed PET-LS nanocomposites disappear, while they have shrunken in PET-silica ones. These findings strongly demonstrate that the dispersed nanoparticles accelerate the crystallization of PET. The dispersed LS particles have higher percolation and nucleation performance than those of silica. The homogeneous distribution morphology of ultrafine particles is easily obtained by controlling the load of their cor-responding precursors. Such a dispersion obviously improves PET properties in that its heat distortion temperature (HDT) increases from 76℃ to 103℃, and crystallization increases 2~4 times more than that of PET. Especially, the nanocom-posite films keep themselves transparent when particle load is within 2 wt.% though there are 3 wt.% or so of agglomer-ated particles in the nanocomposites.

Flame retarded polymer nanocomposites: Development,trend and future perspective

Polymer nanocomposites are a new class of flame retarded materials which have attracted much attention and considered as a revolutionary new flame retardant approach.A very small amount of nano flame retardants (normally < 5 wt%) can significantly reduce the heat release rate (HRR) and smoke emission (SEA) during the combustion of polymer materials.Moreover,the addition of nano flame retardants can also improve the mechanical properties of polymer materials compared with the deterioration of traditional flame retardants.This paper reviews the recent development in the flame retardant field of polymer nanocomposites and also introduces the related research in our lab.The challenges and problems are discussed and the future development of flame retarded polymer nanocomposites is prospected.

Synthesis, characterization and assessment thermal properties of clay based nanopigments

Nano-clay based pigments （NCP） are new type of pigments composed of organic dyes and layered silicate- clay nano-particles, and have already been used in polymeric coatings to improve mechanical thermal and stability properties. In this paper, the basic blue 41（BB41） was intercalated into Na＋- montmorillonite in an aqueous medium. The dye-intercalated montmorillonite was cen- trifuged, dried, and milled to prepare the nanopigrnent particles. X-ray diffraction showed an increase in the basal spacing, thus confirming intercalation of the BB41 molecules within the nanostructures of the interlayer spaces. Fourier transform infrared spectroscopy was used for identifying the functional groups and chemical bounding of Na＋-montmorillonite, BB41 and montmor- illonite-BB41. The morphology of NCP was also studied by transmission electron microscopy. Finally, thermo- gravimetric analysis and differential thermograms sug- gested the thermal stability of the intercalated dye was improved.