Polyethylene electron diffraction patterns

We analyzed the ICB-deposited polyethylene films using JEM-200CX transmission electron microscope. The results show that these thin films were uniform and a mixture of crystalline and noncrystalline phases. The crystalline phase area appears rhombic. Ihe size of the crystalline lamellae is 2-20 mm. The electron diffraction pattern of the crystalline phase appears as an ordered array of spots (Fig. 5a shows a TEM micrograph and Fig. 5b an electron diffraction pattern). The chemical elements of these samples are analyzed with LEED-AES (Parkin-Elmer... 

FIGURE 5 Polyethylene thin film using the ICB-TOFMS deposition system (a) TEM micrograph (b) electron diffraction pattern. 

FIGURE 7 TEM micrograph and electron diffraction pattern of polyethylene on crystalline mica. Moire fringes emerged in the TEM image, indicating interference between the crystalline polyethylene and the crystalline mica. 

Polyethylene was deposited on a single crystalline mica substrate. Larger area moire fringes can appear in the TEM image, caused by interference from the two crystalline thin films, i.e., the crystalline PE thin film and the crystalline mica. Figure 7 shows a TEM micrograph and an electron diffraction pattern. The crystal structure of the mica is monoclinic. The relation of the distances between crystal planes is as follows ... 

When depositing metal clusters in a polyethylene thin film, we obtain polycrystalline thin films with suspended metallic clusters. For the room temperature substrate, the Au cluster size of 2-5 nm is smaller and the clusters are distributed randomly in the polyethylene thin films, shown in Fig. 13a. For a substrate temperature of 90°C, the Au clusters pile up together but still maintain a small spherical form. TTie electron diffraction patterns of the samples with the substrate at room temperature and 90°C are similar (see Fig. 13c), which shows that the Au clusters are crystalline and the polyethylene thin film is polycrystalline. 

Fig. 3.5 Electron diffraction patterns from (A) amorphous carbon, (B) oriented amorphous polystyrene (tensile direction indicated by arrows) and (C) a polycrystalline PE film. The sharpness of the rings in (C) indicates crystalline order. Highly oriented polyethylene is shown in the diffraction pattern (D) (tensile direction indicated by arrows). The off-axis spots prove the presence of three dimensional order.

Fig. 3.15 Sequence of electron diffraction patterns from a polyethylene crystal at 100 kV, showing how the sharp spots fade and spread so the final result is a ring pattern. The crystals have become completely amorphous because of radiation damage. The doses are (A) 35-27 C m (B) 53-55.5 C m" (C) 70.5-74 C m" ...

The single-crystal electron diffraction pattern shown in Figure 6.5 was obtained by viewing the crystal along the c-axis. Also shown is the single-crystal structure of polyethylene, which is typically diamond-shaped (see below). The unit cell is viewed from the c-axis direction, perpendicular to the diamonds. 

Figure 10.12 Electron diffraction pattern from a solution-grown crystal of polyethylene.

Figure 10.20 Electron diffraction pattern from a replica of a spherulite grown in a blend of linear and low-density polyethylene.

The best method for preparation of single crystals of polymers is to grow them from dilute solution. Usually such crystals are small, typically a few micrometres across, and are plate-like with a regular shape that reflects that of the crystal unit cell. The thickness is typically 10 nm. By analysis of electron diffraction patterns from single crystals of polyethylene (the first polymer to be crystallized in this way), it was shown that the polymer... 

Figure 5.22. Electron diffraction pattern (a) and transmission eleotron miorography (b) of a single crystal of polyethylene of pyramidal shape. [Courtesy of J. C. Wittmann, ICS, CNRS Strasbourg (Franoe).]...

Fig. 5.20 Electron diffraction (top left) and defocus phase contrast micrographs of melt drawn polyethylene films. Optical diffraction patterns from the micrographs are at top right. As drawn film (A) is well oriented. Annealing (B) increases orientation and crystal size. Bright regions are interlamellar the crystalline regions are gray or dark if they diffract. (From Yang and Thomas [95] reproduced with permission.)...

Fig. 4.8 Solution-grown polyethylene single crystal, (a) Electron micrograph of a lamellar crystal (courtesy of Dr P. Allan), (b) Selected-area diffraction pattern (courtesy of Dr. l.G. Voigt-Martin). 

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