Flat-on lamellae

Fig. 9 Phase image showing flat-on lamellae surrounded by edge-on lamellae on a BA-C10 film with a thickness of less than 50 nm [64]...

Fig. 9. The crystals in the center area are layer-packed, flat-on lamellae. They were crystallized at 75 °C for 90 h.

An explanation based on simple thermodynamics of the preferred orientation of edge-on and flat-on lamellae on thick and thin films, respectively, was given by Wang et al. [80]. As shown in Fig. 10, a primary rectangular nucleus of size a x a x l can assume either edge-on or flat-on orientation on a sub-... 

Fig. 13 Phase image showing flat-on lamellae of BA-C8 with a spiral structure...

Fig. 3.24 TM-AFM height images of large scale morphology (left) and flat on lamellae (right) spincoated PEO Aims on silicon [60]...

In Fig. 11.14 we can identify several attempts for the onset (nucleation) of flat on lamellae. However, at the temperature of 45°C, even if nucleation... 

Figure 9.9 SEM view of transcrystallinity from glass fiber and illustration of (a) edge-on lamellae and (b) flat-on lamellae. (From Ref. 83, with permission.)...

FIGURE 22.11 AFM amplitude images of PLLA thin films (crystallized at 160°C) prepared from chloroform solutions with the concentrations of 0.25 (a), 0.5 (b), and 2.0% (w/v). The film thicknesses measured by AFM were 20 (a), 50 (b), and 200 nm (c), respectively, (a) Dendritic crystal, (b) hexagonal crystal, and (c) early stage of spherulitic morphology with edge-on and flat-on lamellae. Reprinted with permission from Ref. 65. Copyright 2001, American Chemical Society. 

With decreasing T the faceting of hedrites becomes less evident, evolving to near circular flat-on lamellae [65, 66]. We return to hedrites in Section 3.4.3 when describing the evolution to coarse and then fine-textured spherulites at still lower crystallization temperatures where the diffusion length 5 = DIG decreases further. 

Figure 3.62 Growth at room temperature of PBA-C8 from a small lamellar stack into a hedrite that would constitute the central region of an even larger spherulite. In panel (g) forward, flat-on lamellae can be seen in the polar regions. Note also the dominant lamellae that extend beyond the envelope. Time increments of the AFM images are 14.2 minutes, except 53 minutes between (c) and (d). From Lei et al. [89] with permission from Elsevier.

In another study, banded spherulites of PHBV random copolymer were prepared by isothermal crystallization at 90 C for ten hours.Using tapping-mode AFM, the concentric periodic ridges and valleys on the surface of the banded spherulites of this polymer were found to consist of edge-on and flat-on lamellae, respectively. The periodic concentric ridges and valleys observed by AFM corresponded to the periodic extinction rings observed by polarized optical microscopy. AFM measurements showed that the interaction between the AFM probe and the sample surface can be significantly influenced by lamellar orientation. ... 

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