Transmission electron nanocomposites

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... 

FIGURE 3.3 (a) Transmission electron microscopic (TEM) image of acrylic rubber (ACM)-siUca hybrid nanocomposite synthesized from 10 wt% of tetraethoxysilane (TEOS). (From Bandyopadhyay, A., Bhowmick, A.K., and De Sarkar, M., J. Appl. Polym. Sci., 93, 2579, 2004. Courtesy of Wiley Interscience.) Transmission electron microscopic (TEM) photographs of acrylic rubber (ACM)-silica hybrid nanocomposites prepared from (b) 30 wt% and (c) 50 wt% tetraethoxysilane (TEOS) concentrations. (From Bandyopadhyay, A., Bhowmick, A.K., and De Sarkar, M., J. Appl. Polym. Sci., 93, 2579, 2004. Courtesy of Wiley InterScience.)... 

FIGURE 4.2 Transmission electron microscopic (TEM) image of ethylene-vinyl acetate (EVA)-expanded graphite (EG) (4 wt%) nanocomposites. (From George, J.J. and Bhowmick, A.K., J. Mater. Sci., 43, 702, 2008. Courtesy of Springer.)... 

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 Fe-B nanocomposite was synthesized by the so-called pillaring technique using layered bentonite clay as the starting material. The detailed procedures were described in our previous study [4]. X-ray diffraction (XRD) analysis revealed that the Fe-B nanocomposite mainly consists of Fc203 (hematite) and Si02 (quartz). The bulk Fe concentration of the Fe-B nanocomposite measured by a JOEL X-ray Reflective Fluorescence spectrometer (Model JSX 3201Z) is 31.8%. The Fe surface atomic concentration of Fe-B nanocomposite determined by an X-ray photoelectron spectrometer (Model PHI5600) is 12.25 (at%). The BET specific surface area is 280 m /g. The particle size determined by a transmission electron microscope (JOEL 2010) is from 20 to 200 nm. 

Figure 5 shows the Z-contrast scanning transmission electron microscope (STEM) image of a Ru/Sn02 nanocomposite catalyst prepared by the assembly process [18]. A combined EDX analysis, using an electron beam of... 

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... 

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. 

Fig. 16 Transmission electron micrographs of a CdS, b PbS nanoparticles, and c PbS-coated CdS nanocomposite [142]...

Transmission electron spectroscopy (TEM) studies of the co-deposited thin films revealed a continuos polymer phase with a largely inter-dispersed SiOj regions on a 5-50 nm scale, confirming the nanocomposite morphology. As mentioned in section 3.1.3, parylene thin films obtained are typically highly crystalline. In contrast, SiO is an amorphous material. From X-ray diffraction analyses, it was observed that by increasing the relative amount of polymer in the nanocomposite, the crystallinity was... 

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). 

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... 

FIGURE 13.1 Transmission electron micrographs of mullite composition gels (a) nanocomposite and (b) homogeneons (single phase). 

FIGURE 13.12 Transmission electron micrographs of synthetic nanocomposite opal showing two different arrays of nanosized (7 to 50 nm) Zr02 balls in the void spaces of silica balls. (From Simonton, T.C., Roy, R., Komameni, S., and Breval, E., J. Mater. Res., 1, 667, 1986. With permission.)... 

Fig. 25 Transmission electron micrographs (TEM) of a ternary nanocomposite of PS-poly(ethyl propylene) (PEP) diblock copolymer with two types of nanoparticle-Ugand systems AuR]- and SiO2R2-ftmctionalized (R i, R2 are alkyl groups) nanoparticles of total volume fraction 0.02. The former appear along the interface of the lamellar microdomains, whereas the latter reside in the center of PEP microphases. Schematically, the nanoparticle distribution is shown in the inset. Taken from [308]...

Hence, finite size effects on the optical response of metal nanoparticles are very difficult to take into account in an accurate manner. Moreover, in most experiments carried out on thin nanocomposite films or colloidal solutions the particle size distribution is not mono-dispersed but more or less broad, that can be usually determined by analysis of transmission electronic microscopy images. It should be underlined that the relevant quantity for smdying size effects in the optical response of such media can definitely not be the mean cluster radius , although it is often used in the literature [28-33], since the contribution of one nanoparticle to the optical response of the whole medium is proportional to its volume, i.e. to (cf. Eq. 7). The relevant quantity, that we call the optical mean radius , would then rather be the third-order momentum of the size distribution, = / ... 

Micrograph of PE nanocomposite sample was obtained on a JEM-100B transmission electron microscope at an accelerating voltage of 80 kV. The sample of 70 nm thickness was cut with the aid of LKV-III ultramicrotome from the composite plate prepared by hot pressing. 

The structure of the simple oxides and nanocomposites was characterised by means of X-ray diffraction (XRD), Transmission Electron Microscopy... 

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