Biomass fibres are usually found as short reinforcements which are used to produce mat fabrics. Discontinuous fibres (chopped) are generally used for a randomly ori­ented reinforcement (mat) when there is not any preferential stress direction and/or there is a low stress/strain level in the composite. The alternative to the use of short fibres is the manufacture of long yarns. Yarn is a long continuous assembly of rela­tively short interlocked fibres, suitable for use in the production of textile, sewing, crocheting, knitting, Biomass in Biocomposite Industry

The composite-like structure of natural fibres are generally not single filaments as most man-made fibres, where they can have several physical forms, which depend on the degree of fibre isolation to make them competitive in terms of specific and economic properties compared to synthetic fibre. Physical and mechanical proper­ties of biomass fibre depend on the single fibre chemical composition according to grooving, geometry of the elementary cell and extraction/processing method condi­tions. The earliest review by Maloney (1986) and later Abdul Khalil and Rozman (2004) has outlined a general classification system for various wood-based compos­ites. Conventional wood-based composites (e. g. cellulosic fibreboard, hardboard, particleboard, waferboard, flaxboard, oriented strand board, oriented waferboard) and advanced polymer composites, which frequently termed as biocomposite (e. g. thermoplastic composite, thermoset composite, elastomer composite, hybrid com­posite, and ceramic composite) are classified by specific gravity, density, raw mate­rials and processing methods (Fig. 5.6) . Performance of the composite can be tailored to the end use of the product with each classification category. They are widely used in structural and non-structural applications for both various interior and outdoor structures.

In composite manufacturing, it is crucial to know the fibre characteristics such as shape and aspect ratio as well as their distribution, orientation, alignment, volume fraction and interfacial adhesion in the polymer matrix. Some experimental studies show that fibre orientation plays a very important role in physical and mechanical properties of fibre reinforced nanocomposites (Smith et al. 2000; Shokuhfar et al. 2008; Wang et al. 2008). Rozman et al. (2013) found good mechanical strength and wettability of non-woven composite from kenaf fibre and PP fibre by using carding process and needle punching process. In other case, Shibata et al. (2008) claimed that fibre oriented kenaf reinforced composites can be produced using additional fabrication steps added into compression moulding process. Example for random and oriented kenaf fibre is shown in Fig. 5.7.

Furthermore, nanotechnology is able to manipulate and control fibre-to-fibre bonding at a microscopic level, which offers an opportunity to control nanofibrillar bonding at the nanoscale. Preparation and application of nanocomposites using nano — and microfibrils of biomass fibres are undergoing rapidly in biocomposite science (Bhat et al. 2011; Henriksson et al. 2008; Moon et al. 2006). The fibrillation of pulp fibre from biomass fibres was done to obtain nano-order unit web-like net­work structure, called microfibrillated cellulose. It is obtained through a mechanical treatment of pulp fibres, consisting of refining and high pressure homogenizing pro­cesses. In the range between 16 and 30 passes through refiner treatments, pulp fibres underwent a degree of fibrillation that resulted in a stepwise increase of mechanical properties, most strikingly in bending strength (Abdul Khalil and Rozman 2004; 2010). The bulk of the fibres went through a complete fibrillation that causes the increase in mechanical properties. For additional high pressure homogenization- treated pulps, composite strength increased linearly against water retention values, which characterize the cellulose’s exposed surface area, and reached maximum value at many passes through the homogenizer (Kamel 2007).