Civil Engineering Reference
In-Depth Information
11.2.1
Architecture of Cellulose
As the skeletal component in all plants, cellulose is organized in a cellular hierarchical
structure. h e cell walls of plants are divided by a middle lamella from each other, fol-
lowed by the primary cell wall layer. Cellulose is predominantly located in the second-
ary wall and consists of roughly 6,000 glucose units in the primary cell wall [21-23].
h is linear polymer is composed of repeating β-1, 4 linked anhydroglucopyranose units
that are covalently linked through acetal functions between the equatorial OH group of
C4 and the C1 carbon atom forming bundles of i brils (also called microi brillar aggre-
gates), which allows the creation of highly ordered regions (i.e., crystalline phases)
alternate with disordered domains (i.e., amorphous phases) [24, 25]. Figure 11.1 shows
a schematic wood hierarchical structure from biomass to cellulose nanocrystal (CNC)
and nanoi brillated cellulose (NFC) [26].
11.2.2.
Nanocellulosic Materials Structures and Size
Cellulose nanoi bers are divided into two main families, dif eringin their size and
crystallinity, which are cellulose nanocrystal (CNC) and nanoi brillated cellulose
(NFC). h e CNC, also known as nanowhiskers [27-31], nanorods [24, 32] and rod-
like cellulose crystals [33], which is usually isolated from cellulose i bers through acid
Figure 11.1
A schematic of wood hierarchical structure from biomass to CNC and NFC: (A) Biomass,
(B) single-i ber network, (C) microi bril, (D) cellulose nanocrystal, and (E) nanoi brillated cellulose [26].
