Preparation of Microfibrillar and Nanocrystalline Cellulose

In wood, the cross-sectional diameters of the smallest basic units, often referred to as elementary fibrils, are in the range 2-4 nm. These fibrils are associated in higher systems with diameters of 10-30 nm (microfibrils) [3]. The microfibrils are also known as nanofibrils, protofibrils, and so on. Here the traditional and well-established term microfibril is used. Microfibrils possess a high degree of crystallinity, but along their transverse direction there are localized (paracrystalline) distortions, and they also contain amorphous domains [1, 5, 6]. 

There are two main strategies for disintegration of cellulose fibers down to their microfibrillar components (i) hydrolysis with strong acid and (ii) high shear mechanical treatment. 

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