There are two different types of electron microscopes, scanning electron microscopes (SEM) and transmission electron microscopes (TEM). In the TEM method, an electron beam passes through an extremely thin section of the specimen. You will get a two-dimensional cross-section of the specimen. SEMs, in contrast, visualize the surface structure of the specimen, providing a 3-D impression. The image above was produced by a SEM
Electron microscope method
The electron microscope method is better to examine the surface of the fiber. By electron microscopy, only dry specimen can be examined. And the specimen must be very thin (less than 0.1μm). A limitation is that the specimens must be in a vacuum.
The basic principle is that a beam of electrons is generated by a suitable source. Then the beam scans the surface of the specimen. An image is shown on the monitor screen with spot.
The scanning electron microscope has the great advantage of a much larger depth of focus. In general, this gives much the same sort of information about orientation and crystallinity of fibers.
Properties required for fiber forming polymer
⦿Polymer should be soluble in some solvent from which it can be spun.
⦿Hydroscopic nature should be hydrophilic.
⦿Resistance to different chemicals
⦿ should be near the room temperature.
⦿ 200-300⁰C is suitable.
⦿Orientation, following are suitable…..
⨳ Long and straight chain structure
⨳ Physical & chemical symmetry
⨳ Parallel molecular chain