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Figure 2
(a) Calculated WAXS profile with coexistence of monoclinic and hexagonal crystals in weight ratio of 4:1 gives excellent overlap with experimental data. The upper and lower rows of short rods at the bottom are possible reflections of A-type and B-type crystals, respectively. The dotted curve is the fitting residuals. The arrows mark the (100)H reflection of the hexagonal crystals and the characteristic convoluted peaks at q = 1.21 and 1.28 Å−1 of the monoclinic crystals. Crystal structure projected along the lamellar stacking direction are shown in (b) and (c) for the monoclinic and hexagonal phases, respectively. Each type of unit cell contains two pairs of amylopectin or amylose chains in a double-helical conformation; however, the less compactly packed double helices in the latter case leave a water-rich core that accommodates 4.5 times more water (shown as small dots) than does the more densely packed monoclinic phase.

Volume 1| Part 6| October 2014| Pages 418-428
ISSN: 2052-2525