Where to Search for Peaks of Fibers

If the orientation is uniaxial (i.e., fiber symmetrical), the strong peaks of polymer materials are, in general, found in specific regions of the pattern. The strong WAXS peaks are found close to the equator of the WAXS pattern. Thus it is good practice to let an offset WAXS detector monitor the equator region. 

On the other hand, strong SAXS r ections of uniaxial material are, in general, found on the meridian. So be sure that a SAXS detector covers the meridian whenever fiber material or strained polymers are studied. 

If expected narrow meridional WAXS reflections are not found, the reason may be the bending-away of Ewald s sphere (cf. Fig. 2.6, p. 28). In this case it may be convenient to tilt the sample with respect to the primary beam (cf. Fig. 2.7, p. 29). 

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