Crystallizable chains

We shall only describe here the structure of the LC and LCC phases, because the structures found at temperatures higher than the melting temperature of the crystallizable chains are similar to that of amorphous copolymers. 

In both the LC and LCC structures, the crystallizable drains are folded and a characteristic parameter of these two structures is the number v of folds of the crystallizable chains v is given by the following formula based on simple geometrical considerations... 

The principal factors governing the number of folds of the crystallizable chains are the concentration and the nature of the solvent, the crystallization temperature,the molecular weight of the two blocks, and the nature of the amorphous and crystallizable blocks. The respective influence of these factors has been analyzed in Refs. 

The comparison of copolymers SEO and SCL has shown that the nature of the crystallizable blocks governs both the number of mesophases in the copolymers and the number of folds of the crystallizable chains In a solvent for the crystallizable block as well as in a solvent for the amorphous block, SEO and BEO copolymers dependent on temperature exhibit two mesophases separated by the melting of the PEO chains. SCL copolymers contain mesophases only in a solvent for the amorphous blocks and these mesophases disappears at the melting temperature of the PCL chains, where the two types of blocks become compatible For SEO copolymers containing less than 50% PEO, the number of folds of the PEO chains is determined by the molecular weight of polystyrene which remains the dominating factor at higher PEO contents. For SCL copolymers on the contrary, the number of folds of the PCL chains increases with the PCL content of the copolymer ... 

Several blends prepared by co-precipitation followed by crystallization from the melt exhibit a double melting behavior, due to the occurrence of the secondary crystallization process. The amorphous component causes a retarded crystallization of some of the crystallizable chains, which form lamellae smaller than and located between the primary ones constituting the spherulites (see Figure 3.22). 

According to Stein et al. (84), the diffusion range of the noncrystallizable rubbery chains during the crystallization of crystallizable chains for miscible blends with semicrystalline polymer matrix can be estimated using the parameter 3p (72) as follows ... 

Figure 7.33 Single molecule trajectories showing balance between molar mass and long period. Note the presence of non-crystallizable chain branches in the right-hand case.

Both synthetic and natural polymers are rarely fully crystalline. Even when polymers are crystallizable, only a fraction of the crystallizable chains is incorporated into crystalline domains. Depending on the polymer and the conditions of crystallizations, a significant fraction remains amorphous. Furthermore, polymers usually crystallize in more than one form. These different polymorphs can be identified, and their relative amounts and the fractions of the chains that remain amorphous can be unambiguously assessed from their XRD patterns. 

To investigate the effect of restrictions imposed on crystallizable chains packing in adjacent domains Booth et have studied a range of model completely crystalline oligo(ethylene... 

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