Wide angle X ray scattering

If the polymer sample is oriented, by drawing a fiber, or by applying tension to a film, the crystalhtes tend to become aligned in the direction of the stress, and the x-ray pattern is improved. In some samples of stereoregular or symmetrical polymers, the degree of three-dimensional ordering of the chains may be sufficiently high to allow a structural analysis of the polymer to be accomphshed. 

FIGURE 10.8 X-ray diffraction curves the intensity / as a function of angle for totally amorphous polypropylene (shaded area), and for a sample with a 50% crystalline content. 

Other possible arrangements than the one shown in fig. 10.14 can be used. That arrangement would require corrections for the variation of 

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Cakmak M, Teitge A, Zachman FI G and White J L 1993 On-line small-angle and wide-angle x-ray scattering studies on melt-spinning poly(vinylidene fluoride) tape using synchrotron radiation J. Polym. Sc/. 31 371- 81... 

Copolymers of vinyUdene chloride and methyl acrylate have been studied by x-ray techniques (75). For example, the long period (lamellar thickness) for an 8.5 wt % methyl acrylate copolymer was found to be 9.2 nm by smaH-angle x-ray scattering. The unit cell is monoclinic, with a = 0.686 and c = 1.247 nm by wide-angle x-ray scattering. 

Polyetherimides show no crystallinity as evidenced from calorimetry measurements. The heteroarylene like phenylquinoxaline [27], oxadiazole [30], and benzoxa-zole [56] activated polyethers show TgS from DSC thermograms, with no evidence of crystallization, indicating amorphous or glassy morphology. Furthermore, wide angle x-ray scattering measurements show no evidence of crystalline or liquid crystalline type morphologies, consistent with an amorphous structure. F polyether... 

Tsou and Measmer examined the dispersion of organosUicates on two different butyl mbbers, namely BIMS and brominated poly(isobutylene-co-isoprene) (BIIR) with the help of small angle X-ray scattering (SAXS), wide angle X-ray scattering (WAXS), atomic force microscopy (AFM), and TEM [91]. There is also a patent on BIMS nanocomposites for low permeability and their uses in tire inner tubes [92]. 

Transmission electron microscopy for [Pd/l]coii reveals the presence of small spherical but in some cases agglomerated particles of ca. 4 nm mean size, and wide angle X-ray scattering analyses evidence the fee structure of bulk palladium [44] (Figure 1). 

Table 1 Comparison of degree of crystallinity for metallocene isotactic poly(propylenes) from wide-angle X-ray scattering analyzed by different methods...

Classical X-ray diffraction and scattering is carried out in the subarea of wide-angle X-ray scattering (WAXS). The corresponding scattering patterns yield information on the arrangement of polymer-chain segments (e.g., orientation of the amorphous phase, crystalline structure, size of crystals, crystal distortions, WAXS crystallinity). 

Application. Anomalous X-ray diffraction (AXRD), anomalous wide-angle X-ray scattering (AWAXS), and anomalous small-angle X-ray scattering (ASAXS) are scattering methods which are selective to chemical elements. The contrast of the selected element with respect to the other atoms in the material is enhanced. The phase problem of normal X-ray scattering can be resolved, and electron density maps can be computed. 

Violante A, Krishnamurti GSR, Pigna M (2008) Mobility of trace elements in soil environments. In Violante A, Huang PM and Gadd G (eds) Wiley-JUPAC series on biophysico-chemical processes of metals and metalloids in soil environments. John Wiley Sons, Hoboken, USA Waltham AC, Eick MJ (2002) Kinetic of arsenic adsorption on goethite in the presence of sorbed silicic acid. Soil Sci Soc Am J 66 818-825 Waychunas GA, Fuller CC, Rea BA, Davis J (1996) Wide angle X-ray scattering (WAXS) study of two-line ferrihydrite structure Effect of arsenate sorption and counterion variation and comparison with EXAFS results. Geochim Cos-mochim Acta 60 1765-1781... 

EXAFS information is restricted to the first or second coordination sphere around a central atom whereas WAXS (Wide-Angle X-ray Scattering) can yield information on short and medium range order up to 20 A. It has been applied, for instance, to the important polymeric chain ST material [Fe(Htrz)2trz](BF4) (Htrz= 1,2,4-triazole), in the LS and HS state and indicated the likely involvement of hydrogen bonding between the anion and the 4-H atom of the triazole ring [62]. 

Asakura, T., Sugino, R., Okumura, T., and Nakazawa, Y. (2002a). The role of irregular unit, GAAS, on the secondary structure of Bombyx mod silk fibroin studied with C-13 CP/MAS NMR and wide- angle X-ray scattering. Protein Sci. 11, 1873-1877. 

The mechanical properties also depend on the relative block lengths. For instance, Fluoro-PSB-II is a soft, elastic material. Differential scanning calorimetry (DSC) measurements and wide-angle X-ray scattering (WAXS)... 

Fig. 7 Relative integrated intensities under the peaks (left scale) and relative degree of crystallinity (right scale) obtained from wide-angle X-ray scattering data for D7732C2310 quenched from T = 115 to 30°C. The cooling rate was 30°Cmin 1. The arrow indicates the nominal point at which the final temperature was reached. For convenience, the amorphous peak intensity has been divided by 5. (Reprinted with permission from [ 107]. Copyright 2003 American Chemical Society)...

Figure 11.14 Effect of applied strain on the 002 d-spacing of a PTT fiber drawn at 3.3 x measured by WAXD [76], Reprinted from Polymer, 42, Wu, J., Schultz, J. M., Samon, K. M., Pangelinan, A. B. and Chuah, H. H., In situ study of structure development in poly(trimethylene terephthalate) fibers during stretching by simultaneous synchrotron small- and wide-angle X-ray scattering, 7141-7151, Copyright (2001), with permission from Elsevier Science...

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