Nanocomposites electron microscopy

This is a nonpolar rubber with very little unsamration. Nanoclays as well as nanotubes have been used to prepare nanocomposites of ethylene-propylene-diene monomer (EPDM) rubber. The work mostly covers the preparation and characterization of these nanocomposites. Different processing conditions, morphology, and mechanical properties have been smdied [61-64]. Acharya et al. [61] have prepared and characterized the EPDM-based organo-nanoclay composites by X-ray diffracto-gram (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy... 

FIGURE 2.8 Transmission electron microscopy (TEM) photographs of clay nanocomposites with acrylonitrile-butadiene rubber (NBR) having (a) 50% and (b) 19% acrylonitrile content, respectively... 

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. 

Fig. 1.7 Representative EDS spectra of Na-montmoriUonite. Cu peaks arise from the TEM grid. Reprinted with permission from Yaron-Marcovich D, Chen Y, Nir S, Prost R (2005) High resolution electron microscopy (HRTEM) structural studies of organo-clay nanocomposites. Environ Sci Technol 39 1231-1239. Copyright 2005 American Chemical Society...

Finally, the use of transmission electron microscopy (TEM) is of interest when dealing with the study of residual char obtained when MMT nanocomposites decompose. Figure 10.19 compares TEM images of an original PA6/clay sample with that of its residue collected at 17% sample mass... 

The dispersion morphology of prepared materials was studied with a multitechnique approach, by means of rheology, scanning electron microscopy (SEM), x-ray diffraction (XRD), and nuclear magnetic resonance (NMR). The results of these tests showed that the so formulated PA6 nanocomposites used in the present study are fully exfoliated [1,2],... 

The nanotubes were first oxidized in nitric acid before dispersion as the acidic groups on the sidewalls of the nanotubes can interact with the carbonate groups in the polycarbonate chains. To achieve nanocomposites, the oxidized nanotubes were dispersed in THF and were added to a separate solution of polycarbonate in THF. The suspension was then precipitated in methanol and the precipitated nanocomposite material was recovered by filtration. From the scanning electron microscopy investigation of the fracture surface of nanotubes, the authors observed a uniform distribution of the nanotubes in the polycarbonate matrix as shown in Figure 2.3 (19). 

Figure 2.3. Scanning electron microscopy image of the fracture surface of the polycarbonate nanocomposite. Reproduced from reference 19 with permission from American Chemical Society.

Two specific imaging modes developed in combining ESEM (environmental scanning electron microscopy) and STEM and developed in the MATEIS laboratory can be useful for the characterization of CNT and CNT polymer nanocomposites. 

CNT nanocomposites, even at low CNT volume fractions, provided they form a percolating network. In such cases, it appears that SEM observations show not only the nanocomposite surface topology, but also the CNT arrangement near the surface within a thickness of even few pm. On the other hand, as for other electron microscopy methods, spectroscopy analysis can be used for imaging purposes. 

Intercalated and partially exfoliated PVC-clay nanocomposites were produced by melt blending in the presence and absence of DOP and characterised by X-ray diffraction and transmission electron microscopy. The effects of various factors, including volume fraction of clay, plasticiser content, melt compounding time and annealing, on nanocomposite structure and the thermal and mechanical properties of the nanocomposites were also examined. It was found that the best mechanical properties were achieved at 2% clay loading and 5 to 10% DOP loading. 18 refs. 

Other characterization methods, such as transmission electron microscopy, are necessary for a more complete evaluation of nanocomposite formation. In a similar case, copper hydroxy dodecyl sulfate, with a bilayer packing of anions was found to result in some nanocomposite formation when used in PVE (5). 

The novel SERS-active substrates were prepared by electrodeposition of Ag nanoparticles in the MWCNTs-based nanocomposites. The formation of Ag-MWCNTs nanocomposite was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. The application of the Ag-MWCNTs nanocomposite in SERS was investigated by using rhodamine 6G (R6G). The present methodology demonstrates that the Ag-MWCNTs nanocomposite is suitable for SERS sensor. 

These are very intimate mixtures composed of two or more sohd phases that differ in composition and each with particle sizes of 10 to 20 mn. Solid phases of these dimensions produce sols when dispersed in a liquid. Two or more sols of different composition can be uniformly mixed and gelled to obtain compositionally different nanocomposites. Figure 13.1a shows the transmission electron microscopy (TEM) picture of a sol-gel nanocomposite of mulhte composition consisting of spherical sihca particles (20 nm) and rod-like alumina (boehmite) particles (approximately 7 nm). Such a uniform physical mixture can be distinguished from a homogeneous sol-gel material which does not show any nonuniformity because it is mixed on an atomic scale (Figure 13.1b). The compositionally... 

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