PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
thickness swelling of the boards, but resulted in low strength values. Binderless boards with a higher moisture content could have better properties because the process enables a faster heat transfer to the board’s core and lowers the melting point of lignin. Widyorini et al. (2005a) carried out a study of the chemical changes to kenaf core binderless boards manufactured via steam-injection pressing and hot-press processes. Mild steam injection caused significant degradation of chemical components, resulting in a dark brown board with high dimensional stability values. It is important to obtain the optimum conditions of steam treatment through proper control of steam pressure and pressing time to get the best board properties. Widroyini et al. (2005b) also tried to produce binderless particleboards from bagasse using steam-pressing injection to study the effect of raw materials, storage method, and manufacturing process. It was shown that steam-pressed boards were higher in mechanical and internal bond strength than hot- pressed boards. Oil Palm Oil palm is a lignocellulosic material (in the bark, leaves, fronds, and trunks) rich in sugar and starch and contains cellulose, hemicelluloses, and lignin. According to Anis et al. (2007), Malaysia generates approximately 13.9 million tons (dry weight) of oil palm biomass annually, including the trunk, fronds, and empty fruit bunches. This agricultural biomass is reasonably cheap, abundant, and sustainable, but it is not used effectively and large quantities of these palms are left in the field as underutilised resources. Open burning and landfills are common practices to eliminate oil palm residues, causing environmental problems. Abundance, sustainability, and carbohydrate richness make the oil palm an ideal raw material for the production of value-added, environmentally friendly, binderless composite panels. Suzuki et al. (1998) manufactured binderless boards from steam-exploded pulps of oil palm fronds. The mechanical strengths of the binderless boards produced met the board standard requirements (JIS - A 5908 2003). The binderless boards produced had a dark brown colour with smooth surfaces, which resulted from the degradation of chemical components of oil palm fronds. Rigorous conditions of severe explosion caused great damage, which conferred poor quality on the binderless boards. Hashim et al. (2011a,b, 2012) utilised oil palm biomass consisting of bark, leaves, fronds, mid parts, and core parts of trunks to make binderless boards. All parts of this oil palm biomass consisted of high holocellulose, lignin, starch, and sugar required for self-bonding adhesion. The boards had acceptable properties based on the standard (JIS - A 5908 2003), but were poor in dimensional stability because no pre-treatment was used. Hashim et al. (2010) also mentioned that strands showed better bonding properties characteristics, which enhanced the mechanical properties of panels compared with fine particles. Coconut Husk and Bagasse Coconuts are typically grown in coastal areas of tropical countries. Approximately 15 to 20 million tons of husk is generated annually, making it abundant as a cheap residue from coconut production. Coconut husk comprises 30 wt.% coir fibres and 70 wt.% pith, which must be separated through retting or mechanical decortications, for a wide variety of products such as ropes, yarns, brushes, and mattress padding reinforcement (van Dam 2002). Bagasse is a waste product from sugarcane processing. It is rich in cellulose, which strengthens the fibre shape, thereby increasing water resistance and reinforcing the matrix
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Article 4 – Wood Panels
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