Isothermal crystallization segments

Figure 5.15 Model of structural evolution process in the isothermal crystallization of polyethylene chains. The random chain segments change to the locally regularized trans-form. The stacked lamellar structure is formed with the long period 800 A. The structure changes further to the stacked lamellar structure of 400 A period by inserting the new lamella into the original lamellae. It is noted that the radius of gyration is kept unchanged during this process. (From Reference 46 with permission from the Society of Polymer Science, Japan.)...

Fig. 11.5 Simulation results for the time evolution of structure factors on the isothermal crystallization of homogeneous C2 (a) and C3 (b) solutions with the concentration 0.125 at the temperature. 5EJk (Time periods are labeled in parallel sequences with the curves, in the unit of Monte Carlo cycles). The dot segments represent the initial state (Zha and Hu 2007) (Reprinted with permission)...

Transport Activation Energy of Polymer Segments During Isothermal Crystallization Measured by D and Polarizing Optical Microscopy... 

Figure 5.14 Time dependence of the various structural parameters estimated in the isothermal crystallization process of isotactic polypropylene. The FTIR data show the growth of regular helical segments. The Rg, and L are the radius of gyroid of the higher-density domains, the correlation distance between the neighboring domains, and the long period of the stacked lamellae, respectively, revealed by the SAXS data analysis. The Q is the invariant and is approximately proportional to the degree of crystallinity Xc, which was evaluated also using the WAXD data [67].

Figure 5.16 Structural evolution in the isothermal crystallization process of isotactic polypropylene revealed by a combination of infrared and WAXD/SAXS data. Parts of random coils in the melt are regularized to short helical segments, which form higher density domains in the melt. These domains approach gradually as shown by a correlation distance and change into stacked lamellar structure [67].

When Garg and Misra plotted — log(l —X) versus time using isothermal crystallization data on a polyester-polyamide copolymer, they obtained two straight-line segments [75]. At short times, the slope was close to unity, whereas at later times the slope changed to a value close to 3. What can you speculate about the morphology of the copolymer crystals ... 

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