Natural fibres chemical compositions

However, lack of good interfacial adhesion, low melting point, and poor resistance towards moisture make the use of natural fibre-reinforced composites less attractive. Pre-treatments of the natural fibre can clean the fibre surface, chemically modify the surface, stop the moisture absorption process and increase the surface roughness. Among the various pre-treatment techniques, graft copolymerization and plasma treatment are the best methods for surface modification of natural fibres. Graft copolymers of natural fibres with vinyl monomers provide better adhesion between matrix and fibre. 

The chapter demonstrates that in spite of the incompatibility between hydrophilic natural fibres and hydrophobic polymeric matrices, the properties of natural fibre composites can be enhanced through chemical modifications. The chemical treatments have therefore played a key role in the increased applications of natural fibre composites in the automotive sector. Recent work has also shown that if some of the drawbacks of natural fibres can be adequately addressed, these materials can easily replace glass fibres in many applications. The chapter has also shown that there have been attempts to use natural fibre composites in structural applications, an area which has been hitherto the reserve of synthetic fibres like glass and aramid. The use of polymer nanocomposites in applications of natural fibre-reinforced composites, though at infancy, may provide means to address these efficiencies. Evidence-based life-cycle assessment of natural fibre-reinforced composites is required to build confidence in the green composites applications in automotive sector. 

The performance of natural fibre reinforced polymer composites depends on several factors, including fibre chemical composition, cell dimensions, microfibrillar angle, defects, structure, physical and mechanical properties, and the interaction of a fibre with the polymeric matrix [28]. The knowledge about the characteristics of the fibre is essential in order to expand the effective use of lignocellulosic materials for polyethylene composites and to improve their performance. 

Sepiolite from Vallecas (Spain) with a chemical composition given in Table I, was used as starting material. Following the procedure described previously (8), between 1.7 and 2 meq. g 1 of Na+, La3+, A1, Cr3+ and H+ were introduced in the octahedral sheet of the silicate, replacing the magnesium ions located at the edges of the fibres in natural sepiolite (Figure 1). 

Although jute is a natural fibre like cotton, it differs in chemical composition. Unlike cotton jute contains a high percentage of non-cellulosic matter (about 40%) and the pre-treatment processes of jute are somewhat different from that of cotton. Scouring of jute with caustic soda under pressure cannot be carried out like cotton because of removal of hemi-cellulose which results in high losses of tensile strength (10-15%) and weight (6-8%). 

Composites reinforced with short natural fibres has been done, as a matrix used polyester resin. The natural fibres such as palm-fibre and coir-fibre have been treated with chemical and mechanical treatment. The mechanical properties of composites with treated natural fibres better than untreated natural fibres composites. 

Composite materials reinforce with natural fibre can be tailoring to specific properties by the length of the fibre, degree of roughness, type of chemical treatment, also low cost to produced that composite materials. 

Properties such as density, electrical resistance, ultimate tensile strength and initial modulus are related to the internal structure and chemical composition of the fibres. Properties may also vary according to variations in diameter along with the length of individual filaments, size and maturity, as well as the processing methods used for the extraction of fibres. These fibres are biodegradable and non-abrasive. However, incompatibility of the fibres and poor resistance to moisture often reduces the potential of natural fibres and these drawbacks have become a critical issue in their development." ... 

Mean chemical composition of some natural fibres [7]... 

Table 13.1 Chemical compositions of different types of natural fibre. ...

ATR-FTIR, solid state C-NMR and XRD results showed the composition of the fibre surface and the relationship of its characteristic with thermal resistance. The crystalline content of the natural fibre remarkably increased after chemical treatment, which was confirmed by XRD and solid-state C-NMR. HCIO4 is the most efficient chemical in terms of wax and fatty acid residue removal in our work. Hence, the dynamic mechanical properties of the natural fibre after HCIO4 treatment were improved. It was reported that the acidolysis lignins were isolated from sugar cane bagasse and curaua fibres by adding a mixture of dioxane and 0.1 N aqueous HCl (8.5 1.5, v/v) at 100 °C for 2 h under N2. ATR-FTIR and TGA of the oxidized lignins revealed a decrease in... 

The chemical composition as well as the morphological microstmcture of vegetable fibres is extremely complex due to the hierarchical organisation of the different compounds present at various compositions. Depending on the type of fibre, the chemical composition of natural fibres varies. Primarily, fibres contain cellulose, hemicellulose and lignin. The property of each constituent contributes to the overall properties of the fibre. 

John MJ, Anandjiwala RD (2008) Recent developments in chemical modification and characterization of natural fiber-reinforced composites. Polym Compos 29 187-207 Joshy MK, Mathew Lovely J (2006) Rani studies on short isora fibre-reinforced polyester composites. Compos Interfaces 13(4—6) 377-390 Kicinska-Jakubowska A, Bogacz E (2009) Private sources of INEMP... 

Sreekala MS, Kumaran MG, Thranas S (2000) Effect of chemical modifications on the mechanical performance of oil pabn fibre remfoicedphtmol formaldehyde composites. In natural polymers and composites. In Capparelli Mattoso LH et al. (ed) Embrapa Instrumentacao Agropecuaria,... 

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