Polysaccharides general concepts

Crystallinity in polymers was first observed by X-Ray Diffraction even before these materials were understood to be polymers. Prominent examples were polysaccharides, especially cellulose (Herzog et al. 1920) and stretched natural rubber (Katz 1925). This was before Staudinger s macromolecular concept was widely accepted (Morawetz 1995). By the time synthetic crystalline polymers such as polyethylene (in 1933) and nylons (in 1935) were developed, it was generally acknowledged that the unit cell of a polymer crystal was based on repeating monomer units, rather than on the whole molecules. 

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