The properties of biomass has been studied for decades; however the data were different among cited works because different types of biomass were used, different moisture conditions were present and different methods were employed. Researchers concluded that the overall properties of agricultural biomass are determined by large variables including its structure, chemical composition, cell dimension and microfibril angle. Furthermore these properties are also varying considerably between plant species and even in the same individual plant (John and Anandjiwala 2008).

5.3.1 Chemical Properties

Plant biomass is primarily composed of cellulose, hemicelluloses and lignin along with smaller amounts of pectin, protein and ash (Kumar et al. 2009). Cellulose is a semicrystalline polysaccharide made up of D-anhydroglucose (C6H11O5) units linked together by p-(1-4)-glycosidic bonds. It provides strength, stiffness and structural stability of the fibre which help to maintain the structure of plants and serves as a deciding factor for mechanical properties. Hemicelluloses are branched and fully amorphous polymers. Meanwhile, lignin is a complex hydrocarbon polymer with both aliphatic and aromatic constituents. Lignin is associated with the hemicellu — loses in plant cell wall and plays an important role in the natural decay resistance of the biomass material (Majhi et al. 2010). Table 5.1 shows the variability in cell wall composition in biomass. The table shows that content of the polymers are highly variable depending on the plant species. The composition, structure and properties of biomass depend on plant age, soil condition and other environmental factor including stress, humidity and temperature (Jawaid and Abdul Khalil 2011). The polymer chemistry of these fibres will affect their characteristics, functionalities and properties processing in different applications (Gorshkova et al. 2012).