**4. Natural fibres and their utilization in bio-composites**

A vast number of research papers and reviews are available for utilization of natural fibres in sustainable development of biocomposites. However, as mentioned, the fibres are sustainable raw materials and may be obtained from different sources from nwfps, further, low-cost, light-weight, availability, renewability, biodegradability; properties and strength are important factors for their utilization. The specific properties of the fibres are utmost important in developing the composites. Natural fibres comprise of cellulose, hemicelluloses, lignin, waxes and tannins etc. The percentage of these constituents varies with the source and processing of fibres. Further, the properties of biocomposites are also dependent upon the source of fibres and presence of these constituents. Natural fibres are obtained from plants or animals [35]. The plant fibres are commonly used for producing bio-composites and mostly sourced from nwfps or in some countries cultivation of these crops is being carried out for sustainable production. The commercial sources of fibres utilized in producing biocomposites worldwide due to their inherent properties. The classification of fibres based on source, their specific properties and utilization in biocomposites are summarised in **Tables 1-3**.

Natural fibres show a variation in properties. The fibre properties are dependent on the geographical location, process of isolation (ratting of fibres) and maturation period. However, some fibres exhibit highest tensile strength in a range from 300- 1100 MPa (**Table 1**).
