Lamellar formation

However, the essential mechanisms of lamellar formation and growth are found to be the same in both the united-atom and explicit-atom models. Only the united-atom model simulation results are therefore discussed in Sect. 3. 

Fig. 4.5. Schematic representation of the lamellar formation of a regioregular polythiophene system via intermolecular side-chain interdigitation.

For powder samples with Tpoiy = 20 °C, the lamellar formation begins at Tas exceeding 110 °C, which is a little lower than the corresponding Ta of 120 °C for the powder of Tpoiy = 70°C. The WAXD data recorded while these nascent... 

PP/EVAl PP-MA/EVAl Maleic anhydride grafted PP lamellar formation, permeability barrier Lohfink 1990 Lohfink and Kamal 1993... 

More recently Hoffman and co-workers attacked the kinetics of polymer crystallization anew (41,76-80). Hoffman began with the assumption that chain folding and lamellar formation are kinetically controlled, the resulting crystals being metastable. The thermodynamically stable form is the extended chain crystal, obtainable by crystallizing under pressure (89). 

Figure 5 illustrates the application of our method for a 3D melt of block copolymers under simple steady shear flow. Applying shear speeds up the lamellar formation in a diblock copolymer melt enormously. The alignment qualitatively differs from the 2D case—so-called perpendicular lamellae are formed in 3D. From experiments and stability analysis this orientation is well known to be the most stable one (see, e.g., [31]). The structure remains stable after switching off the shear. 

FIG. 9 Lamellar formation of an AsBs copolymer melt in the presence of square plates of one grid-cell thickness. The interaction of polymer blocks with the surface is 1.0 and (a) View of filler particle in simulation box, (b)... 

FIG. 10 Lamellar formation of an copolymer melt in the presence of the same... 

SEM also has been used, for example, to establish the orientation of lamellar formations for poly(styrene-/>/ocfe-4-trimethylsilylstyrene) (PS-/>-PTMSS) and... 

From H-NMR analysis, the crystallinity decreases and exhibits a minimum value around 60 °C, then increases as the temperature increases. These decrement and subsequent increment in crystallinity coincide with those of the reflection intensities observed for the variable-temperature WAXD profile. Heating produces maximum crystallinity at about 120 °C followed by the abmpt drops in crystallinity, which is attributed to the sample melting. These temperatures of the maximum crystallinity coincide well with the temperatures at which the lamellae appear in the TEM observations. These results indicate that the lamellar formation originates from melt recrystallization during annealing. 

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