Spherulites polarized optical image

Fig. 6 Polarizing optical images of PHB and PHBCN2 (2 wt% nanoclay) before and after 6 weeks of biodegradation. The samples were crystallized at 100 C prior to composting to generate different spherulite microstructures [32]...

Figure 38 Polarized optical image of a film of PVDF (SOLEF 6010), which was isothermally crystallized at 162.5 °C. The semicrystalline morphology exhibits large banded sphemlites typical of the a-phase, while the smaller more disordered sphemlites reveal a curled lamellar morphology as shown in the inset. (Inset) AFM image (5x5 im ) of the y-spherulite morphology of PVDF. "...

Typical polymer materials studied in optical thin section include extrudates or molded parts, such as semicrystalline polyoxymethylene multiphase polymers, such as rubber toughened nylon filled polymers, such as carbon black filled nylon fibers, such as polyester and rayon and films which are too thick to transmit light. Two examples are of nylon imaged in polarized light (Fig. 4.9A), which reveals its spherulitic texture, and imaged in bright field (Fig. 4.9B), which reveals the dispersed carbon black particles. 

Figure 5.7. Optical microscope image of a thin film (thickness 2 p.m) of a-p-NPNN grown on a glass substrate (1.6 x 1.0 mm, crossed polarizers). Reprinted from Journal of Crystal Growth, Vol. 209, J. Caro, J. Fraxedas and A. Figueras, Thickness-dependent spherulitic growth observed in thin films of the molecular organic radical p-nitrophenyl nitronyl nitroxide, 146-158, Copyright (2000), with permission from Elsevier.

Polyethylene has to a large extent dominated morphological studies in polymer systems however, it is a good model for other systems. Optical microscopy of acetal shows the same characteristic patterns found in polyethylene when a spherulite is viewed under cross-polar imaging (Figure 5.14). 

Fig. 1. A series of images showing the growth of spherulites of polyethylene. The uniformity of spherulite size, and the linear intersection of the spherulites once crystallization is complete, can be clearly seen. Exposures taken after the marked times. Optical micrographs with the sample between crossed polars. Reprinted from Ref 19. Copyright (1982), with permission from John Wiley Sons, Inc.

Fig. 5.63 Transmitted light micrographs of a glass fiber reinforced polyamide polished thin section is shown by three optical techniques. Imaging in bright field (A) reveals clear, round fibers aligned perpendicular to the section plane and a mottled textured matrix. Polarized light (B) shows the glass fibers are isotropic (black) whereas the polymer is birefringent and composed of finely textured spherulites. Phase contrast (C) shows that there are small, white regions of different refractive index than the matrix.

Figure 3.15. Two images of a thin melt cast film of high density polyethylene the region is 200 x 250//m. The left hand image was taken in crossed polars. The radial Maltese cross is due to the extinction position. The spherulites in this material have dark circumferential bands. The crystals twist as they grow, and their orientation in these bands has the optic axis perpendicular to the specimen plane. The right hand image is the same area when a first order red plate is also used. The blue and yellow colors show that the spherulites are negative. (See color Insert.)...

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