Bright field imaging examples

Fig. 2.20 Examples of electron micrographs of polymers, (a) A defocussed bright-field image of a thin film of isotactic polystyrene annealed and crystallised at about 170 °C (b) An image of a fracture surface replica from a sample of linear polyethylene crystallised from the melt at 4.95 kbar. ((a) Adapted by permission of Masaki Tsuji and (b) adapted from Principles of Polymer Morphology by D. C. Bassett. Cambridge University Press 1981.)...

In some studies, a statistical description of the nanotube dispersion state was obtained from TEM images. For example, Uchida et al. (56) measured the diameter distribution of SWNT bundles in poly(acrylonitrile), with and without a purification treatment involving sonication in methanol. The different bundle diameter distributions (especially the mean diameter) could explain the different composite tensile moduli. Fornes et al. (57) also determined the diameter distribution of SWNTs bundles in a polymer matrix (namely polycarbonate). To improve the contrast in the bright-field TEM images and better measure the bundle diameter, they dissolved the polymer in chloroform and studied the remaining SWNT network. 

Fig. 5.50 Microstructure of t-Zr02, precipitates in c-Zr02 matrix in Mg-PSZ. The c axes of two of the three possible precipitate variants, which are parallel to the cube axes, are shown. The third variant cannot be imaged under the diffracting conditions of this example. Bright-field electron micrograph [13]. With kind permission of John Wiley and Sons...

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. 

---