Electron diffraction montmorillonite

Science. Vol.297, No.5582, pp.787-792, ISSN 0036-8075 Beermann, T. Brockamp, O. (2005) Structure analysis of montmorillonite crystallites by convergent-beam electron diffraction. Clay Miner. Vol.40, No.l, pp.1-13, ISSN 0009-8558... 

Nylon-6. Nylon-6—clay nanometer composites using montmorillonite clay intercalated with 12-aminolauric acid have been produced (37,38). When mixed with S-caprolactam and polymerized at 100°C for 30 min, a nylon clay—hybrid (NCH) was produced. Transmission electron microscopy (tern) and x-ray diffraction of the NCH confirm both the intercalation and molecular level of mixing between the two phases. The benefits of such materials over ordinary nylon-6 or nonmolecularly mixed, clay-reinforced nylon-6 include increased heat distortion temperature, elastic modulus, tensile strength, and dynamic elastic modulus throughout the —150 to 250°C temperature range. 

The minerals found in United States coals continue to be studied with the availability of improved instrumental procedures such as x-ray diffraction, infrared absorption, and scanning electron microscopy beyond the traditional optical and chemical mineralogical techniques as applied to thin sections, polished pellets, and isolated particles. The minerals may be grouped into the silicates (kaolinite, illite montmorillonite, and chlorite), the oxides (quartz, chalcedony, hematite) the sulfides (pyrite, marcasite, and sphalerite) the sulfates (jarosite, gypsum, barite, and numerous iron sulfate minerals) the carbonates (ankerite, calcite, dolomite, and siderite) and numerous accessory minerals (apatite, phosphorite, zircon, rutile, chlorides, nitrates, and trace minerals). 

The clay minerals used in this study were kaolinite (AI281205(OH) ), illite (Kj A1jSi2+ (OH)2), and montmorillonite which was approximately 1/2 (Ca, Na)Q (Al, Mg, Fe) (Si, ADqO q (OH). n H2O. The clays were natural samples purchased from Ward s Natural Science Establishment, Inc. The kaolinite sample was obtained from a kaolin deposit in Georgia. X-ray diffraction (XRD) patterns on this material showed peaks only for kaolinite, and scanning electron micro-scope-energy dispersive x-ray (SEM-EDX) analysis yielded peaks for Al, Si, and minor amounts of Ti. The illite was a green shale from New York which Ward s listed as 85% illite. XRD patterns of this... 

P. Bar-On, I. Shainberg, and I. Michaeli, Electrophoretic mobility of montmorillonite particles saturated with Na/Ca ions, J. Colloid Interface Sci. 33 471 (1970). R. D. Harter and G. Stotzky, X-ray diffraction, electron microscopy, electrophoretic mobility, and pH of some stable smectite-protein complexes. Sod Sci. Soc. Am. J. 37 116 (1973). S. L. Swartzen-Allen and E. Matijevi6, Colloid and surface properties of clay suspensions. II Electrophoresis and cation adsorption of montmorillonite, /. Colloid Interface Sci. 50 143 (1975). 

Botana et al. [50] have prepared polymer nanocomposites, based on a bacterial biodegradable thermoplastic polyester, PHB and two commercial montmorillonites [MMT], unmodified and modified by melt-blending technique at 165°C. PHB/Na and PHB/ C30B were characterized by differential scanning calorimetry [DSC], polarized optical microscopy [POM], X-ray diffraction [XRD], transmission electron microscopy [TEM], mechanical properties, and burning behavior. Intercalation/exfoliation observed by TEM and XRD was more pronounced for PHB30B than PHB/Na,... 

Recently, in our group, we evaluated the potentiality of a poly(iniide) (PI)/ organically-modified montmorillonite (O-MMT) nanocomposite membrane for the use in alkaline fuel cells [73]. Both X-ray diffraction and scanning electron microscopy revealed a good dispersion of O-MMT into the PI matrix and preservation of the O-MMT layered structure. When compared to the pure PI, the addition of O-MMT improved thermal stability and markedly increased the capability of absorbing electrolyte and ionic conductivity of the composite. Based on these results, the PI/ O-MMT nanocomposite is a promising candidate for alkaline fuel cell appUcations. 

Structure-property relationships in crosslinked polyester-clay nanocomposites, prepared by dispersing methyl tallow bis-2-hydroxyethyl quaternary ammonium chloride-modified montmorillonite in prepromoted polyester resin and subsequently crosslinking using the methylethylketone peroxide initiator at room temperature and at several clay concentrations, were analyzed by X-ray diffraction combined with Transmission Electron Microscopy (TEM), thermal (TGA) and dynamic mechanical analyses as well as by the determination of mechanical and optical properties [158]. In all cases the formation of a nanocomposite and the morphology of a dispersion of intercalated/exfoHated aggregates of clay sheets in the resin matrix were confirmed (Fig. 17). hi the absence of reflection irrespective of clay concentration in the scattering curves for all the polyester-clay nanocomposites was ascertained. 

The arrangement of montmorillonite, hectorite, and nontronite is always turbostratic. Figure 6 shows an electron selected area diagram produced by a single thick particle of montmorillonite. The stacked layers show certain tendencies to preferential orientation, but the degree of disorientation is important (in the order of 10°). In certain montmorillonites, like those of Wyoming, the mutual orientation of the layers is absolutely arbitrary the diffraction spots are uniformly spread out on circles (Mering and Oberlin [1967]). 

Figure 6. Electron selected area diffraction diagram of a single thickness of a particle of montmorillonite (Camp Berteaux). It should be noted that the stacked layers are mutually disoriented by rotations about an axis, which is perpendicular to them. This disorientation characterizes a turbostratic structure.

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