Wide-angle X-ray scattering - WAXS

If a monochromatic X-ray beam is incident on a polymer sample, scattering is observed at angles a of about 10-50° from the direction of the incident beam. Taking a typical angle of 23° = radian and assuming an X-ray wavelength X of about 2 nm, standard diffraction theory shows that this implies that there are units present in the polymer with dimensions d given approximately hy d = X/a = = 0.5 nm, which is of 

9 Wide-angle X-ray scattering from (a) polystyrene, showing a diffuse halo from an amorphous sample and (b) highly crystalline polyethylene, showing sharp powder rings. (Courtesy of Dr A. P. Unwin.) 

If a stretched fibre of a crystalline polymer is placed in the X-ray machine, a so-called fibre pattern is observed (fig. 3.10). As discussed in chapter 4, this pattern contains information about the crystal structure of the polymer. It also contains information about the size of the crystallites and about their degree of alignment, topics discussed further in chapters 5 and 10, respectively. 

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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]. 

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). 

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... 

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)... 

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. 

Figure 6. Wide angle X-ray scattering (WAXS) results of CTA-HPL copolymers. (A) CTA (control) (B) copolymer with 80% CTA content and (C) copolymer with 60% CTA content.

Waychunas, G.A., Fuller, C.C., Rea, B.A. and Davis, J.A. (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. Geochimica et Cosmochimica Acta, 60(10), 1765-81. 

The more detailed study of the crystallite size distribution and crystallite arrangement in PPX matrix was carried out for cryochemically synthesized nanocomposite PbS-PPX films in the range of PbS content from 4.7 to 10.2 vol.%. The distribution curves obtained from analysis of wide-angle X-ray scattering (WAXS) data is presented in Figure 10.5 [71, 86]. The curve for nanocomposite with 4.7 vol.% of PbS differs a little from histograms of the crystallite size distribution determined by TEM for nanocomposite films Ag-PPX and Pb-PPX with low metal content [75, 80]. It means that, as the average size of crystals, distribution in the sizes almost does not depend on nature of M/SC incorporated in polymer as a result of cryochemical synthesis. 

We have studied the effect of heating on the color, on the dry and wet tensile properties, on the abrasion characteristics, and on the dyeing and resultant color properties of the linen. We also examined the effect of heat treatment on the crystallinity of flax by wide angle X-ray scattering (WAXS) and on the surface morphology of flax fibers by scanning electron microscopy (SEM). 

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