Interspherulitic region

Figure 5.17 Images of a PEG-PVAc blend system showing the typical behavior for (a) parallel polarized, (b) perpendicular polarized and (c) dichroic ratio images. The bottom images generated by plotting the 1721 cm- carbonyl stretching band of PVAc for both (d) parallel and (e) perpendicular polarization show that PVAc is located mainly in the interspherulite regions. Reproduced from figure 3 of Ref. 31, with permission.

According to Cimmino et al. [25], OM measurements show that in the melt (340 °C) demixing of PVME occurs at all compositions, and during crystallization segregated PVME particles remain occluded in the interspherulitic region of sPS crystals. At the end of the crystallization process, an increase in the spherulite dimensions is observed, indicating that PVME addition reduces the nucleation ability of sPS. 

This equation represents a generalization of the additivity of microhardnesses for high-crystallinity polymers, see eq. (4.3). However, Hsph and Ha, instead of describing the crystal and amorphous hardness, now represent the microhardnesses of the spherulites Hsph — 200 MPa) and interspherulitic regions Ha — 120 MPa), respectively. 

At low G values, there is a higher probability that all dispersed particles can diffuse fast enough away from the growth front and be pushed along until complete crystallization. The second phase component will then be found mainly in the interspherulitic regions. 

Here, Hsph is the hardness value of the spherulites, i a is the hardness of the amorphous interspherulitic regions, and is the volume fraction of... 

Here, i/gph is the hardness value of the spherulites, is the hardness of the amorphous interspherulitic regions, and is the volume fraction of crystallized spherulites. During primary crystallization, Hgph remains constant and hardness is directly proportional to the volume occupied by the spherulites (12). The hardness variation in the course of isothermal crystallization of PET and poly(ethylene naphthalene-2,6-dicarboxylate) (PEN) has been shown to follow Avrami law (13,14). 

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