TEM scans

As an indication of the changes in deformation modes that can be produced in ionomers by increase of ion content, consider poly(styrene-co-sodium methacrylate). In ionomers of low ion content, the only observed deformation mode in strained thin films cast from tetra hydrofuran (THF), a nonpolar solvent, is localized crazing. But for ion contents near to or above the critical value of about 6 mol%, both crazing and shear deformation bands have been observed. This is demonstrated in the transmission electron microscope (TEM) scan of Fig. 3 for an ionomer of 8.2 mol% ion content. Somewhat similar deformation patterns have also been observed in a Na-SPS ionomer having an ion content of 7.5 mol%. Clearly, in both of these ionomers, the presence of a... 

As one example, in thin films of Na or K salts of PS-based ionomers cast from a nonpolar solvent, THF, shear deformation is only present when the ion content is near to or above the critical ion content of about 6 mol% and the TEM scan of Fig. 3, for a sample of 8.2 mol% demonstrates this but, for a THF-cast sample of a divalent Ca-salt of an SPS ionomer, having only an ion content of 4.1 mol%, both shear deformation zones and crazes are developed upon tensile straining in contrast to only crazing for the monovalent K-salt. This is evident from the TEM scans of Fig. 5. For the Ca-salt, one sees both an unfibrillated shear deformation zone, and, within this zone, a typical fibrillated craze. The Ca-salt also develops a much more extended rubbery plateau region than Na or K salts in storage modulus versus temperature curves and this is another indication that a stronger and more stable ionic network is present when divalent ions replace monovalent ones. Still another indication that the presence of divalent counterions can enhance mechanical properties comes from... 

Figure 7.3 Schematic set-up of an electron microscope in the trans-mission (TEM), scan-ning (SEM), and com-bined (STEM) mode (figure after Sanders f 101).

With the aid of this prototype, an adequate scanning unit -interfaced to the TEM -scans with pre-determined step size resolution- a part or whole of ED pattern against a fixed detector. Electron beam is deflected by means of deflector coils in the TEM which are situated after the sample. Fixed detector can be either a combination of a scintillator and a photomultiplier or a Faraday cage (one or multiple). Detector is fitted at the bottom of the TEM column, but can also be adapted in the 35 mm port, if the port below the TEM column is occupied by e g. a CCD camera (see fig. 1). 

In addition to surface analytical techniques, microscopy, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning tunneling microscopy (STM) and atomic force microscopy (AFM), also provide invaluable information regarding the surface morphology, physico-chemical interaction at the fiber-matrix interface region, surface depth profile and concentration of elements. It is beyond the scope of this book to present details of all these microscopic techniques. 

Cryo-transmission electron spectroscopy (TEM), scanning electron spectroscopy, and confocal laser scanning microscopy smdies indicated the presence of large. 

Transmission electron microscope (TEM) Scanning transmission electron microscope High-resolution electron microscope Analytical electron microscope... 

Transmission electron microscopy (TEM) Scanning electron microscopy (SEM)... 

In the author s opinion, the better approach to experimentally study the morphology of the silica surface is with the help of physical adsorption (see Chapter 6). Then, with the obtained, adsorption data, some well-defined parameters can be calculated, such as surface area, pore volume, and pore size distribution. This line of attack (see Chapter 4) should be complemented with a study of the morphology of these materials by scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning probe microscopy (SPM), or atomic force microscopy (AFM), and the characterization of their molecular and supramolecular structure by Fourier transform infrared (FTIR) spectrometry, nuclear magnetic resonance (NMR) spectrometry, thermal methods, and possibly with other methodologies. 

TEM scans of typical air crazes in PS samples of low and high molecular weight are shown in Fig. 12. It is evident from these TEM micrographs, as well as from the SEM scan of the fracture surface of PSAN shown in Fig. 10, that the craze is a highly deformed, localized planar region with sharp boundaries separating it from the bulk... 

Figure 8.36 (a) Typical TEM scan of calcined KSW-2 (pH 4.0) and the corresponding electron diffraction ED pattern indexed as hkO projection, (b) Typical TEM and the corresponding ED pattern of as-made KSW-2 (pH 6.0). (c) Another TEM scan of the as-synthesized KSW-2 (pH 6.0). Arrows imply the observed place of the bending of silicate sheets derived from kanemite. Reproduced with permission from [156], Copyright (2000) Wiley-VCH. 

The carbon fiber support and the catalysts before and after reduction were characterized with various techniques, viz. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), temperature programmed reduction (TPR), Nz-physisorption, inductively coupled plasma emission spectrometry (Vista AZ CCD simultaneous ICP-AES) and hydrogen chemisorption. 

Microscopy is a key approach which is frequently used for the characterizatitm of composite latex particles. There are a wide range of microscopes which can be used to analyze latexes, such as the optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), scanning transmission electron microscope (STEM) and the atomic force microscope (AFM). The choice of the microscope technique depends on the resolution and size range needed (i.e. nanometres to microns). The most important factor in microscopy is contrast. If the contrast is low, it becomes very difficult to distinguish between... 

We are interested in three quantities (1) the size of the pores, (2) the distribution of the porosity, and (3) the total amount of porosity in the sample. Usually the actual shape of the pores is less important, although there may be situations in which the shape would be a critical factor. We can see pores in transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AEM). If they are large enough, we will also see them in visible light microscopy (VLM). None of these observations will give a statistical measurement of the... 

The chemical structure of the two polymers can be characterized by several techniques Fourier transform infrared (FTIR) nuclear magnetic resonance (NMR) x-ray diffraction (XRD) transmission electron microscopy (TEM) scanning electron microscopy (SEM) mass spectroscopy (MS) ultraviolet spectrometry (UV) and electron scanning for chemical analysis (ESCA). The chemical structure of the two polymers can be analyzed by IR, NIR, or various types of NMR spectroscopy. Determining the structure of chitin and chitosan usually requires the application of combination of various methods. The combination of IR, NIR, and various techniques of NMR give ample information on the chemical structure. IR, NIR, and various types of NMR are less sensitive than that of other quantitative analysis such as UV, HPLC, GC, and MS. 

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