Spherulites, optical micrographs

To confirm the shape of the spherulites described by the Avrami exponent, polarized optical micrographs of the isothermal crystallized melt blends were taken, and are shown in Figure 20.26 [44],... 

Figure 4 Optical micrograph of spherulites formed by slow coagulation of an isotropic solution of PBT in MSA, viewed between crossed polarizers.

Figure 2. Optical micrographs of the (a) banded and (b) unhanded spherulitic morphologies obtained under different crystallization conditions...

Figure 3 Polarizing optical micrographs of poly(ethylene terephthalate) (PET) crystallized at 240°C in the absence (A) and in the presence (B) of a shearing. As a consequence of the shearing, nucleation becomes increasingly profuse, and the shape of the spherulites becomes elliptical. (From ref. 11)...

Figure 45. Optical micrographs, between crossed polarizers, of alkane C162H326 to which 10 wt % was added of (a) C122H2461 and (b) C246H494. Tc = 120 °C. The mixture with the longer-chain guest molecules (b) shows a texture resembling that of polymer spherulites (from ref 204 by permission of American Chemical Society).

Optical microscopy using polarized light gives a first hint on the crystallinity of the obtained structures. A typical result of optical micrographs obtained without polarization, parallel and perpendicular orientation of the polarizer and analyzer are shown in the Fig. 4. If the relative position of the polarizer and analyser is changed the different regions of the spherulites change their colour, while the... 

Closer inspection reveals that besides fibrils, spherical domains are also observed in STS-1 and to a lesser extent in ST-1 and ST-2. Thus, fibrils and spherical domains co-exist. Increase in PS content in the block copolymers results in progressively smaller spherulites, and a very rough surface for the STS-5 film is observed in the optical micrograph. 

Figure 12.19. Optical micrographs of (a) PPBS spherulites, (b) PPBC spherulites in the presence of EPDM and (c) PPBC spherulites nucleating from interface with EPDM.

Figure 9.20 Optical micrographs of spherulites during crystallization at 403K, (a) iPP/EP92 (50/50) blend, (b) 1PP/EP89 (50/50) blend, (c) iPP/EP84 (20/80) blend, (d) iPP/EP77 (20/80) blend, (e) EP84, and ( EP77. (Erom Reference 37 with permission from Elsevier Ltd.)...

Figure 16.8 shows the development of spherulitic morphology in the 50/50 iPP/ EPDM blend (6) upon cooling from 230°C to ambient at a slow cooling rate of 0.5°C min As depicted in Fig. 16.8a, the polarized optical micrograph under the cross... 

Fig. 1. Optical micrographs (crossed polaroids) of spherulites growing in thin films of PEO/PMMA blends of various compositions a) PEO/PMMA 90/10, Tp = 53 C b) PEO/PMMA 80/20,...

Optical micrographs of cross sections of the extruded HDPE/iPP (25/75) filaments show a fine morphological structure with micro-spherulites aligned along telescopic rings (Fig. 11). In the decentralized centre of the filament there is a zone of almost circular shape with different morphology this region contains mainly HDPE. 

Fig. 3.13 An optical micrograph of spherulites of polyipropylene terephthalate) grown from the melt. (Courtesy of Dr M. A. Wilding.)...

The optical micrographs taken of sample A recrystallized from melt temperatures of 170, 200, and 230°C show that the morphology varied from row to mixed to spherulitic. The line nucleus seemed to break down into shorter lines and finally to a high concentration of points. 

Optical micrographs showing the growth of PE spherulite structures (from ref. 16). 

Banded spherulities of linear polyethylene within a commercial pellet. Optical micrograph of a thin section viewed between crossed polars. Note that sequences of spherulites have nucleated along lines, here in black contrast, which are probably a legacy of extrusion (after D. C. Bassett.). Scale bar -10 un. 

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