Transmission electron microscopy nanocomposite morphology

Recent demands for polymeric materials request them to be multifunctional and high performance. Therefore, the research and development of composite materials have become more important because single-polymeric materials can never satisfy such requests. Especially, nanocomposite materials where nanoscale fillers are incorporated with polymeric materials draw much more attention, which accelerates the development of evaluation techniques that have nanometer-scale resolution." To date, transmission electron microscopy (TEM) has been widely used for this purpose, while the technique never catches mechanical information of such materials in general. The realization of much-higher-performance materials requires the evaluation technique that enables us to investigate morphological and mechanical properties at the same time. AFM must be an appropriate candidate because it has almost comparable resolution with TEM. Furthermore, mechanical properties can be readily obtained by AFM due to the fact that the sharp probe tip attached to soft cantilever directly touches the surface of materials in question. Therefore, many of polymer researchers have started to use this novel technique." In this section, we introduce the results using the method described in Section 21.3.3 on CB-reinforced NR. 

The morphology of the nanocomposites was studied with Transmission Electron Microscopy (TEM JEM-2000 EX-11 at 200 kV). Samples for TEM were prepared by standard procedures, including separation of the nanocomposite layer from the NaCl substrate in water and the film deposition onto a Cu grid for further derailed investigations. The metal content of the composites was calculated by atomic absorption analysis using a Perkin-Elmer 503 spectrometer. 

For the comprehension of mechanisms involved in the appearance of novel properties in polymer-emhedded metal nanostructures, their characterization represents the fundamental starting point. The microstructural characterization of nanohllers and nanocomposite materials is performed mainly by transmission electron microscopy (TEM), large-angle X-ray diffraction (XRD), and optical spectroscopy (UV-Vis). These three techniques are very effective in determining particle morphology, crystal structure, composition, and particle size. 

The morphology of the nanocomposites was studied by transmission electron microscopy TEM using LEO 912AB OMEGA instmment. The size distribution of nanoparticles was figured out by statistical treatment of 50-100 particle size. 

Zhang et al. [63] prepared styrene-butadiene nanocomposites by dispersing an aqueous dispersion of montmoril-lonite and latex and flocculating the dispersion with acid. The performance of the rubber nanocomposites were compared with clay, carbon black, and silica rubber composites prepared by standard compotmding methods. The montmoriUonite loadings for the rubber nanocomposite were up to 60 phr. The morphology of the rubber nanocomposites by transmission electron microscopy appears to indicate intercalated structures. The mechanical properties of the rubber nanocomposites were superior to all of the other additives up to about 30 phr. However, rebound resistance was inferior to all of the additives except sUica. The state of cure was not evaluated. 

Crosslinked NR nanocomposites were prepared with montmorillonite. Morphology was characterized using transmission electron microscopy (TEM), wide-angle X-ray scattering (WAXS), and dynamic mechanical analysis (DMA). X-ray scattering patterns revealed clay intercalation and TEM showed dispersion with partial delamination. The loss modulus peak broadened with clay content, while Tg remain constant. Montmorillonite reinforced the rubber. The DMA exhibited non-linear behaviour typified as a Payne effect (see Section 20.11) that increased with clay content and was more pronounced for this type of nanocomposite. Viscoelastic behaviour was observed under large strains via recovery and stress relaxation. ... 

Transmission electron microscopy (TEM) is another useful tool for the morphological and structural analysis of nanomaterials. Thompson et al. [89] worked on isotactic (iPP)/EPDM/organoclay nanocomposites and concluded that the uniaxial plane deformation caused by compression of the nanocomposites contributed to the... 

The two basic tools used to elucidate nanocomposite morphology are x-ray diffraction (xrd) and transmission electron microscopy (tern). They provide complementary information on clay dispersion in the host matrix. 

Information on the nanocomposite morphology was obtained by transmission electron microscopy (TEM) and x-ray diffraction (XRD) observation. Compounding was done on a twin-roll mill, and exfoliated silicate sheets were observed together with small stacks of intercalated sheets." This structure may be described as a semi-intercalated semi-exfoliated structure that did not change principally with the vinyl acetate content of the EVA matrix, even a larger number of stacks were observed for EVA with lower vinyl acetate contents." There were no great differences within the morphology of these nanocomposites. 

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. 

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