Polyethylene lozenge-shaped crystals

Figure 5.3 Transmission electron micrograph of a solution-grown single crystal of linear polyethylene showing lozenge-shaped crystals.

Figure 3.33 AFM image of a polyethylene chair crystal similar to that in Figure 3.13b, but viewed directly from above. Note the right-handed spiral growth on the upper half, and the left-handed spiral on the lower half. A lozenge-shaped crystal with a centrally located spiral growth is on the far right. From Toda et al. [19] with permission from Elsevier.

Fig. 10 Four common types of crystal habit in polyethylene and long alkanes (a) rhombic lozenge bounded by 110 facets (b) lozenge truncated by curved 100 faces (Toda s type B) (c) leaf-shaped crystal bounded solely by curved 100 faces (step propagation rate v equals h = Gno/sin(

Fig. 2.15 Several lozenge-shaped polyethylene single crystals grown from xylene solution (from Geil (1963) courtesy of Geil).

Electron microscopy provides experimental evidence of the nature of the fold surface. The observation of distinct sectors in lozenge-shaped polyethylene crystals provides strong evidence for folds that occur preferentially along the 110 [118]. Attempts to predict or model the possible fold conformations in polyethylene crystals have been made over the years [123]. Generally, results have been extensively dependent on the contributions to the potential energy included in any particular model [124]. 

Figure 3.6 Sketch of top views of lozenge-shaped (left, as in Fig. 3.1) and truncated lozenge-shaped (right, as in Fig. 3.16) crystals of polyethylene. The crystallographic a-axis it to the right and 6-axis is vertical up. Adjacent reentry folding is assumed along each growth face. Solid lines represent successive fold planes, while dotted lines indicate sector boundaries that separate distinct fold domains. From Wunderlich [6] with kind permission from the author.

Figure 334 Edge view along the short A-axis diagonal of a lozenge-shaped polyethylene crystal suspended in solution. The spiral growth layers are clearly splayed from one another. See text for more discussion. Phase contrast optical micrograph from Mitsuhashi and KeUer [52] with permission from Elsevier.

Figure 5.3 Morphologies of polyethylene single crystals (a) lozenge-shaped tent type, (b) truncated-lozenge-shaped tent type, (c) two halves of truncated lozenge-shaped chair type, and (d) truncated lozenge-shaped chair type with spiral terraces from screw dislocations [11].

Figure 7 Polyethylene lamellae crystallized from solution (a) lozenge shaped (b) truncated lozenge shaped...

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