Nanocomposites WAXD patterns

Figure 8.27 Stress-strain curves and selected WAXD patterns acquired during stretching of pure copolymer (unfilled circles) and 10 wt% nanocomposite (filled circles) at room temperature. (Reproduced from Reference (49) with permission from Elsevier Science.)...

Additionally, some layered silicates initially do not exhibit well-defined basal reflections. Thus, peak broadening and intensity decreases are very difficult to study systematically. Therefore, conclusions concerning the mechanism of nanocomposites formation and their structure based solely on WAXD patterns are only tentative. On the other hand, TEM allows a qualitative understanding of the internal structure, spatial distribution of the various phases, and views of the defect structure through direct visualization. 

Fig. 10. (a) WAXD patterns and (b) TEM images of three different types of nanocomposites... 

Figure 8.14 WAXD patterns of various NR-EOMt nanocomposites.

WAXD patterns of pure OMt, EOMt and nanocomposites with various EOMt contents are shown in Figure 8.16. The mean interlayer spacing of the if(001) plane for the OMt obtained by WAXD measurements was 2.98 nm (26 = 2.78°). The interlayer distance of OMt was further expanded to 4.42 nm after successful intercalation with long alkyl chain C22 fatty add. In the scattering pattern three sharp peaks appeared at 20 = 2.1°, 5.4° and 9.4°, respectively. These were in addition to three broad peaks of Mt. These sharp... 

Figure 22.4 Sequential variation of WAXD patterns from (a) pure NR and (b) MWCNT-NR nanocomposites. Corresponding strain values are indicated at the top left in each pattern of panels a and b.

Figure 22.5 Equatorial diffraction profiles taken from 2D WAXD patterns at selected strain values of MWCNT-NR nanocomposites (a) and pure NR (b) as a function of strain under stretching at the W angle range of 10-28.3°.

Fig. 4 WAXD patterns of Qoisite SOB clay and SMPU/clay nanocomposites of different clay contents, dooi = l -8nm is the d-spadng of Cloisite SOB and the numbers refer to the different clay contents in the composites. Reprinted from [77], Copyright 2007, with permission from Elsevier...

Figure 5.8 WAXD patterns and TEM images of different types of nanocomposites.

Eigure54 shows the WAXD patterns obtained for neat Cloisite 30B ground cured PCN/Cloisite 30B mechanical blend, as a model of the PCN/MMT system without interactions between the components, and for one of PCN/Cloisite 30B nanocomposites investigated. The main diffraction peak of neat Cloisite 30B indicates the interlayer spacing of 1.92 nm the same is observed for the mechanical blend. The diffraction peak was shifted towards lower angles in the diffractograms... 

Fig. 54 WAXD patterns of(l) Cloisite 30B, (2) PCN/Cloisite 30B (95/5) nanocomposite, and (3) PCN/Cloisite 30B (95/5) mechanical blends are shown [226]. Interlayer spacings are indicated...

WAXD difiractograms of intercalated or otherwise stacked tactoid structures may show second-order and even third-order reflections, which are assodated to very ordered stacking of the intercalated layers [24,26,28,45-48]. On the other hand, the absence of high order (001) peaks in the WAXD patterns of nanocomposites, especially with low amounts of MMT fillers, can be due to different reasons, such as a decrease in the regularity of the stacking layers or a diminution of the size and number of tactoids with highly parallel stacking, and a consequent increase in the proportion of exfoliated silicate layers dispersed in the polymer matrix [27,49]. 

Fig. 1 presents the XRD patterns of epoxy/a-ZrP nanocomposites with (a) poor exfoliation, (b) moderate exfoliation, and (c) good exfoliation. All three WAXD patterns show an amorphous epoxy hump at around 18Tof 20. In the poorly exfoliated system (Fig. 1(a)), even though all the peaks from pristine a-ZrP have disappeared, new peaks due to the intercalated a-ZrP layers can be observed. This indicates that intercalated a-ZrP layers are still present in epoxy matrix. WAXD patterns obtained from the moderate and well exfoliated nanocomposites, as shown in (b) and (c), do not show any intercalation peaks, indicating that both of these nanocomposites do not have noticeable intercalated nanoplatelets in the epoxy matrix. However, a minor distinction between WAXD patterns in Fig. 4(b) and Fig. 4(c) can still be found at around 3 5T of 20. TEM investigations were also performed to validate the WAXD observation (to be presented). 

Figure 1 shows the WAXD patterns of Cloisite 30B clay and PU/clay nanocomposites. A peak at 20=4.9° in clay curve manifests that it had an interlayer spacing of 1.8nm. No peak is observed in the nanocomposite with lwt% clay, indicating fully exfoliated state. To confirm this result, TEM image was taken and single layers can be... 

A novel nanocomposite membrane, poly dimethyl siloxane (PDMS)/Au was prepared for carbon dioxide/methane separation. Synthesis of stabilized nano particles is also reported. The nanoparticles were characterized by UV-visible spectroscopy and transmission electron microscopy (TEM). The hybrid membrane was characterized morphologically by scanning electron microscope (SEM) and the change in inter-segmental distance due to filler loading by wide angle X-ray diffraction patterns (WAXD). The gas transport properties were measured at different pressures and temperatures. The effects of filler loading on permselectivity, diffiisivity selectivity and solubility selectivity are reported for CO2/CH4 separation. Reverse selective phenomena of PDMS/Au nanocomposite membrane over the conventional PDMS membrane is explained based on sorption kinetics of CO2. 

---