Kenaf fibre

Polylactic acid (PLA) reinforced with kenaf fibres developed by NEC for personal computer housings. With a 20% level of kenaf fibres, the main properties compete with glass fibre reinforced ABS but the cost is 50% higher. The flexural modulus is more than 4.5 GPa and the HDT reaches 120°C. 

In terms of green composite or bio-composite, the sol-gel sihca can be applied to natural fibres. An earlier work reports the generation of sihca into the voids of kenaf fibre about 20% of nano-silica could be incorporated into the fibre. Figure 7.2 showed the incorporation of sol-gel silica in the void of kenaf fibres. The kenaf sol-gel silica mixture could be used to prepare bio-composites or green composites by choosing the right polymer matrices. 

Kenaf fibre s void filled with sol-gel silica... 

Figure 7.2 SEM showing the presence of sol-gel silica in the void of kenaf fibre.

Yu H, Yu C (2007) Study on microbe retting of kenaf fibre. Enzyme Microb Technol 40 1806-1809... 

Lee BH, Kim HS, Lee S, Kim HI, Dorgan JR et al (2009) Bio-composites of kenaf fibres in polylactide role of improved interfacial adhesion in the carding process. Compos Sci Technol 69 2573-2579... 

Sanadi AR, Caulfield DF, Jacobsaon RE, Rowell RM (1995) Renewable agricultural fibres as reinforcing fillers in plastics mechanical properties of kenaf fibre-polypropylene composites. Ind Eng Chem Res 34 1889-18%... 

Nishino et al. [18] used kenaf fibre sheets in an attempt to fabricate composites with better dispersion and adhesion. The kenaf fibre was dried, and then soaked in a dioxane solution under vacuum. These samples were easily fabricated and exhibited... 

H. Ismail, A.M.Norjulia, andZ. Ahmad, Theeffectsofuntreatedandtreatedkenafloading on the properties of kenaf fibre-filled natural rubber compounds. Polym. Plast. Technol. Eng. 49(5), 519-524(2010). 

M.R. Islam, M.D.H. Beg, and A. Gupta, Characterization of laccase-treated kenaf fibre reinforced recycled polypropylene composites. Bioresources 8(3), 3753-3770 (2013). 

Historically, kenaf fibre was first used as cordage. Industry is now exploring the use of kenaf in papermaking and non-woven textiles. Like jute, most kenaf composite products exploit the long aspect ratio of kenaf fibres and fibre bundles. One way to do this is to form the kenaf into a non-woven textile mat that can be used for erosion control, seedling mulches or oil spill absorbents. After a resin is added to the kenaf mats, they can be pressed into flat panels or moulded into shapes. 

In another study (Wambua et al., 2003), mechanical properties of the different natural fibre composites have been tested and compared with glass mat-reinforced polypropylene composites and tend to be quite similar. It can be tmderlined that impact properties of hemp appear to outperform kenaf fibres. 

In terms of crystallization and thermal behaviour, no significant effect of cellulose on PHB crystallinity was reported. A slight increase of Tg and a delay in the crystallization process were observed. The presence of cellulose fibres also increases the rate of PHBV crystallization, due to a nucleating effect, while thermal parameters, such as crystallinity content, remained unchanged. Studies on the crystallization behaviour of PHB/kenaf fibre biocomposites showed that the nucleation by kenaf fibres affected the crystallization kinetics of the PHB matrix. Differences in the effect of cellulose fibres on the crystallization process have been attributed to the lignin content at the surface/interface of the cellulose fibre. 

Figure 6.4 FOMA(TM) N70HECO phone made of PLA bioplastics reinforced with kenaf fibres developed by NEC, UNITIKA and NTTDoCoMo Paul Fowler [50]...

Table 1. Chemical composition of kenaf fibre after each stage of treatment.

Figure 3. (a) FTIR spectra of raw kenaf fibre, (b) Alkali treated fiber, Bleached fiber (c), and cellulose nano whiskers (d). 

Figure 6. X-ray diffraction pattern of (a) Rae kenaf fibre, (b) Alkali treated kenaf fibre, (c) Bleached kenaf fibre, (d) cellulose nanowhiskers.

Other uses of core kenaf fibre include also soil-less potting mixes, animal bedding, oil absorbents, packing material, organic filler for plastics, drilling mud binder, grass and flower mats, decorative fibres and insulation as well as animal feed and human food [41]. Bast fibre is also blended with cotton and used in textiles [41]. The bast fibre of kenaf can also be mixed with plastic for injection moulding. 

Ghasemi I, Azizi H, Naeimian N (2008) Rheological behaviour of polypropylene/kenaf fibre/ wood flour hybrid composite. Iran Polym J I7(3) 191... 

Alkbir MEM, Sapuan SM, Nuraini AA, Ishak MR. Effect of geometry on crashworthiness parameters of natural kenaf fibre reinforced composite hexagonal tubes. Mater Des 2014 August 60 85-93. 

Ardente F., Beccali M., Cellura M. and Mistretta M. (2008) Building energy performance A LCA case study of kenaf-fibres insulation board , Energy and Buildings, Vol.40, pp.1-10. 

G. Phiri, M. C. Khoathane, and E. R. Sadiku, Effect of fibre loading on mechanical and thermal properties of sisal and kenaf fibre-reinforced injection moulded composites. J. of Reinforced Plastics and Composites 33 (3), 283-93 (2014). 

A commercial paper-like sheet of kenaf fibre was converted to a composite material by impregnation with a solution of a commercial L-PLA in dioxane solution (Nishino et al, 2002). Following this procedure, a composite material with 70% v/v fibre content was obtained. Tensile tests showed that a maximum tensile stress of about 60 MPa was found for the best composite material, comparing with a value of about 20 MPa for the unreinforced polymer processed in the same way. Similarly, a tensile modulus of about 6 GPa for the kenaf-PLA composite compared with a value of just over 1 GPa for the unreinforced polymer. The authors concluded that good stress transfer fi om the resin to the matrix had been obtained. In research by Shibata et al (2003), a flexural modulus of 5.5 GPa was achieved at 20% w/w abaca fibre content in a PLA composite. This result compares with a flexural modulus of 3.5 GPa for the unreinforced pol3mier. A further increase in flexural modulus was obtained when... 

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