Interlamellar amorphous model

Figure 2.17 Schematic representation of (a) fofd plane showing regular" chain folding, (b) ideal stacking of lamellar crystals, (c) interlamellar amorphous model, and (d) fringed micelle model of randomly distributed crystallites.

Overall, the data were taken to indicate that the PCL blocks tended to be incorporated into the crystalline lamellae in a manner similar to the PCL homopolymer. The polybutadiene blocks were thus located in the interlamellar amorphous regions and contributed to the ring-banding. It is not clear if the polybutadiene block was uniformly distributed in the amorphous regions but in the preferred model there was some segregation of PB and PCL within the amorphous regions. 

Figure 26 Schematic illustration of the two possible models of the lamellar stack of semirigid chain polymers. Left, stacks with thin crystals and thicker interlamellar amorphous regions. Right stacks with thicker crystals and thinner interlamellar amorphous regions. The ambiguity of the microstructural model Is due to the Babinet principle, which makes the scattering from the two structures indistinguishable.

FIGURE 4.6 Compromise model showing folded-chain lamellae tied together by interlamellar amorphous chains. 

Fig. 4. Molecular model of a stack of parallel lamellae of the spherulitic structure A, interlamellar tie molecule B, boundary layer between two mosaic blocks C, chain end in the amorphous surface layer (c ilium) D, thickness of the crystalline core of the lamella E, linear vacancy caused by the chain end in the crystal lattice L. long period I, thickness of the amorphous layer (Peterlir ).

Since a substantial amount of material is contained in the interlamellar region, the properties of the latter give significant contributions to the overall material behavior. The properties of the interlamellar material he between those of the unconstrained amorphous melt and those of the crystalline phase [9-11], and the influence of the crystalline constraints can be addressed experimentally [12-14]. Furthermore, the properties of the crystal-melt interface have various ramifications that can be observed experimentally [15], e.g., interface stresses lead to distortion of the crystal lattice spacing [16-18], and they are possibly responsible for lamella twisting [19]. In addition, the surface tension enters in theoretical models for crystallization rates [20,21]. 

It was realised by Takayanagi [50] that oriented highly crystalline polymers with a clear lamellar texture might be modelled in terms of a two-component composite in which the alternating layers corresponded to the crystalline and amorphous phases [51]. The model was later extended to include a parallel component in addition to that in series, and was applied first to describe the relaxation behaviour of amorphous polymers with two distinct phases, and later to crystalline polymers in which the parallel component represented either interlamellar crystalline bridges or amorphous tie molecules threading through the amorphous phase. 

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