General Properties of Lignocellulosic Fiber as Fillers

GENERAL PROPERTIES OF LIGNOCELLULOSIC FIBER AS FILLERS Chemical Composition 

The three principal components of plant materials are cellulose, lignin, and hemi-cellulosics. Cellulose and hemicellulosics are polysaccharides. Cellulose is a highly regular structure, crystalline polymer, made up of thousands of glucose residues, covalently bound head-to-tail (Fig. 3.1). 

Lignin is a phenol propane-based amorphous solidified resin, filling the spaces between the polysaccharide fibers. Lignin is not just a concrete but also a highly engineered chemical structure (Fig. 3.2). 

Besides these three principal components, plant materials contain nonstructural components—extractives (typically 4-10%), inorganic ash (between 0.2 and 0.5% in wood and up to 19% in rice hulls and some other plant materials), and water. Examples of extractives are terpenes, pinenes, tannins, carbonyl compounds, and so on. They contribute to wood odor, can diffuse to the wood surface during drying and can affect adhesion, and some of them possess antimicrobial properties. 

The term lignocellulose, often used for description of plant materials, does not properly describe their main components. Besides cellulose and lignin, the third main component, as indicated above, is hemicellulose, or, more correctly, hemicel-lulosics. The plural form here reflects a set of various heteropolymeric saccharides, the so-called matrix plant polysaccharides. These hemicellulosics mainly form 

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GENERAL PROPERTIES OF LIGNOCELLULOSIC FIBER AS FILLERS TABLE 3.7 Mechanical properties of filled Nylon 6 composites [135]... 

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