Small-angle X-ray diffraction technique

Along with the indirect chemical methods (radical acceptors and monomers), the mechano-chemical mechanism is sustained by the data obtained using electronic paramagnetic resonance spectroscopy (EPR) for the characterisation of free radicals [907], The identification of the new end-functional groups, obtained by radicals stabilisation has been performed by FTIR spectroscopy [908], Complementary results were obtained using mass spectroscopy, MS, and small angles X-ray diffraction techniques. 

Cationic quaternary ammonium compounds such as distearyldimethylammonium-chloride (DSDMAC) used as a softener and as an antistatic, form hydrated particles in a dispersed phase having a similar structure to that of the multilayered liposomes or vesicles of phospholipids 77,79). This liposome-like structure could be made visible by electron microscopy using the freeze-fracture replica technique as shown by Okumura et al. 79). The concentric circles observed should be bimolecular lamellar layers with the sandwiched parts being the entrapped water. In addition, the longest spacings of the small angle X-ray diffraction pattern can be attributed to the inter-lamellar distances. These liposome structures are formed by the hydrated detergent not only in the gel state but also at relatively low concentrations. 

The above disadvantage of the lack of spatial information can be overcome by a combination of NMR data and other techniques. From the aH pulse NMR, the fraction and the molecular mobility of different molecular environment can be obtained as free induction decays (FIDs) within a short time, which is suitable for a practical, better understanding of the morphology-property relationship. Wide angle X-ray diffraction (WAXD) and small angle X-ray diffraction (SAXD) as well as electron microscopy provide direct information between the nano- and micrometre scale. A combination of NMR data with those from X-ray diffraction and electron microscopy should be able to analyse the structure from the atomic level to the macro scale. In this review, the morphology-property relationship, the dynamics of morphological transition, the kinetics of crystallisation, etc. analysed by a combination of NMR and other tools are introduced. 

A Leitz Ortholux microscope was used for the optical micrographs. Electron micrographs were obtained by conventional techniques using an International Scientific Instrument Co. minielectron microscope. Crystallinities were determined calorimetrically from the ratio of the heats of fusion of the semicrystalline samples measured (17) experimentally on a Perkin Elmer DSC-1B to the heat of fusion for 100% crystalline HMS of 32 cal/g reported by O Malley (9, 16). Wide and small angle x-ray diffraction were obtained using a G.E. XRD-5 x-ray diffractometer. 

Recently, Kinney etal. [2004] used the technique of resonant ultrasound spectroscopy (RUS) tomeasure the elastic constants (Qj) of human dentin from both wet and dry samples. As (%) and Ac (%) calculated from these data are included in both Table 47.5 and Figure 47.4. Their data showed that the samples exhibited transverse isotropic symmetry. However, the Qj for dry dentin implied even higher symmetry. Indeed, the result of using the average value for Q i and Cu = 36.6 GPa and the value for C44 = 14.7 GPa for dry dentin in the calculations suggests that dry human dentin is very nearly elastically isotropic. This isotropic-lifce behavior of the dry dentin may have clinical significance. There is independent experimental evidence to support this calculation of isotropy based on the ultrasonic data. Small angle x-ray diffraction... 

Even in dilute solutions they associate (49, 50). Published sizes of the micelles vary from 2 to 4 run. Sophisticated analytical techniques such as small-angle X-ray diffraction (SAXS), small-angle neutron scattering (SANS), and NMR were used to study the asphaltene particle or micelle sizes (51). MacKay (15) reported that a MWtof 10,000 g/mol would correspond to a 2 to 4-nm cluster. This is very much smaller than a 1-pm water droplet, and considered to be 1/100 to 1/1000 the droplet diameter. This topic is worthy of a review on its own. However, the colloidal properties of asphaltenes, micelles, and... 

The quality, perfection, and stability of the layered assemblies and details of their internal architecture can be analyzed by a combination of different methods such as X-ray diffraction, spectroscopic (IR, UV/Vis, Raman) techniques, wave-guide spectroscopy and so on [74]. As an example. Figure 9.5 shows the small-angle X-ray diffraction pattern obtained at a grazing incident from an assembly of 28 copoly(glutamate) layers on a silicon wafer [82,83]. The insert represents a molecular picture of the assembly with only two of the 28 layers drawn. 

The principle of using X-ray (powder) diffraction (XRPD) to detect stability is to monitor the change of crystallinity over time under different temperature and humidity conditions (Greco et al. 2012). The advantage of this technique is that the temperature can be both above and below Tg. Small-angle X-ray diffraction (XRD) can also be used (Zhu et al. 2010). The onset of crystallization, too, is hence obtained. 

Analytical Techniques. Analytical techniques to determine the structure of carbon fibers include wide-angle and small-angle x-ray diffraction, electron diffraction, neutron scattering, Raman spectroscopy, electron microscopy, and optical microscopy. Detailed reviews of these techniques are found in the literature. ... 

It has long been considered that the most useful workhorse techniques, for a modestly equipped laboratory concerned with charcterising polymeric materials, are differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), wide and small angle X-ray diffraction (WAX and SAXS), thermogravimetric analysis (TGA) and optical and electron microscopy. 

Small-angle and wide-angle x-ray diffraction techniques have been reviewed in several articles and books [207-211]. 

Information on the morphology of polymers is revealed by techniques such as powder X-ray diffraction (PXRD), which is often called wide-angle X-ray scattering (WAXS) by polymer scientists, and small-angle X-ray scattering (SAXS). The crystallites exist in a polymer sample below the melting temperature T, an order-disorder transition, above which a viscous melt is formed. 

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