Lamellae orientation

Fig. 6 Micromechanical model of a section of a semi-crystalline polymer with lamellae oriented perpendicular to the principal stress direction showing the long period L and the thicknesses of crystalline (Lc) and amorphous layers (La) the latter are composed of loose segments, entangled chains and more or less extended tie molecules. Large forces can be transferred at those points (o) where highly extended tie molecules (eTM) enter crystalline lamellae...

At the late stage of lamella orientation, classical topological defects (dislocations and disclinations) dominate [40, 41] (Fig. 8h and Fig. 9), and their movement and annihilation can be followed in Fig. 8h-i and Fig. 9. The latter presents an example of the apparent topological defect interactions and their transformations. Displayed are two dislocations of PMMA, which have an attractive interaction due to their opposite core sign. Therefore, in the next annealing step the dislocation is shifted... 

Olszowka V, Tsarkova L, Boker A (2009) 3-Dimensional control over lamella orientation and order in thick block copolymer films. Soft Matter 5(4) 812—819... 

Figure 26 shows typical order parameter profiles obtained across the films at various temperatures. Due to the repulsive wall-A interaction the order parameter pA(z)-pB(z) is always depressed towards negative values for z near the walls. From previous studies of the same model in the bulk [190,191] one expects an order-disorder transition to a lamellar phase for T=2 (note AB/kB=l), and consequently one sees for D=20 and D=30 well-developed lamellae oriented parallel to the walls, evidenced by the periodic variation of the order parameter across the film, with an amplitude close to the saturation value unity already. However, for D=14 the system does not develop this type of order, and for D=24 there seems to be well-developed order near the right surface but not near the left surface, which is unexpected since both surfaces are equivalent. 

The lamellae oriented with the fold surfaces perpendicular to the extrusion direction (perpendicular lamellae) also Increases in number up to EDR -4.6, and then rapidly disappear between EDR 4.6 and 6. 

FIGURE 13.15 Electron micrc raphs of SI diblock copolymer (MW = 524,000 g/mol, 52% styrene) at a free surface, (a) Lamellae oriented parallel to surface (typically observed), (b) Lamellae oriented perpendicular to surface (occasionally observed). The arrows indicate the locations of the free surfaces. (From Hasegawa and Hashimoto (1985) reprinted (adapted) with permission from ACS, copyright 1985.)... 

For a lamellae orientation parallel to the substrate, hole mobility values as high as 0.1 cm T s were found. In this context, work with isolated linear polymer chains (molecular wires) is also noteworthy [44]. It revealed that the hole transport mobility along isolated polymer chains can exceed 0.1 cm s , as can be seen in... 

In conclusion we have reached a morphology of stable lamellae oriented perpendicular to a nontreated substrate. Similar results have recently been reported by Hashimoto and co-workers using conventional lamellar block copolymers on a strongly corrugated substrate [46]. In both situations azimuthal ordering of the lamellae turned out to be difficult. We wanted to extend these experiments to a cylindrical morphology for which we should... 

D. Xu, Y. Song, X. Shi, P. Tang, M. Matsuo, Y. Bin, Temperature dependence of lamellae orientation of a branched low molecular weight polyethylene/ultrahigh molecular weight polyethylene blend film under a controlled temperature gradient Polymer 54, 4037-4044 (2013)... 

FIGURE 16 Electron micrographs of SI diblock copolymer (MW = 524,000g/mol, 52% styrene) at a free surface, (a) Lamellae oriented parallel to surface, (b) Lamellae oriented perpendicular to surface. 

Unlike commonly applied interdigital multilamination approach, split-and-recombine (SAR) mixing relies on a multiste p procedure. According to its name, the basic operations are the splitting of a bi- or multilayered stream perpendicular to the lamella orientation into substreams and their subsequent recombination [33]. This concept is schematically represented in Figure 4.19a. For this purpose, basically three steps are required flow splitting, flow recombination, and flow... 

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