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journal of materials research and technology 2022;20:4630 e 4658
Fig. 13 e Particleboard made of oil palm frond (left), oil palm trunk (middle), and empty fruit bunch (EFB) (own photo).
particleboard manufacturing. However, every type of agri- cultural biomass has its own issue that prevents it to be used effectively. Bagasse is among the best materials for particle- board manufacturing as particleboard manufactured from it often displayed satisfactory physical and mechanical prop- erties. Still, in some case, the incorporation of some portion of wood particles are necessary to further enhance its perfor- mance. Straw-, leaves- and grass-based particles suffered from the waxy surface layer that prevents the effective spreading of water-based UF resin and inevitably leads to poor adhesion and bonding. Meanwhile, hull-, husk- and shell- based particleboard has low mechanical strength due to the low cellulose content of the raw materials. On the other hand, stalk-based particleboard has high holocellulose content that resulted in high thickness swelling. Palm-based such as OPT and OPF has high carbohydrate content but low lignin content while EFB has comparable cellulose content but lower lignin content with hardwood and softwood. Interventions have been carried out by many researchers to enhance the perfor- mance of the agricultural biomass-based particleboard. Most of them involve the incorporation of wood particles or using higher resin content. For agricultural biomass having waxy surface layers, isocyanate-based adhesives such as MDI and pMDI are recommended. Polyurethane (PUR), PVA (polyvinyl alcohol), PVAc (polyvinyl acetate), and acryl-based adhesives are suitable options too. Silane coupling agents have also been used to improve the bondability of straws.
investigate the effects of hydrothermal treatments of wood particles on the physical and mechanical properties of recycled-wood particleboard. The hydrothermal treatment was utilized to degrade the bonding of UF adhesive in old and faulty particleboard to retrieve the detached wood particles for new particleboard production. It was revealed that the MOR value of the boards showed a significant reduction. Similar results were also reported in other literature and were mainly due to the thermal decomposition of wood [167 e 169]. However, it is worth noting that the MOE value of the recycled- wood particleboard was significantly higher when compared to the control particleboard. To fully understand the effect of thermal treatment on the properties of the boards, the authors suggested that a chemical composition analysis of the treated particles be conducted in future studies. The authors also suggested that to produce particleboard that meets re- quirements at the time, a mixture of new particles and recy- cled wood particles treated with the milder hydrothermal condition could be used in the production.
5.
Particleboard made from recycled wood
A summary of the physical and mechanical properties of particleboard produced using recycled wood waste as raw materials is presented in Table 10. The surface appearance of the post-production particleboard is shown in Fig. 14. Most studies looked at the effect of different types of wood waste, different ratios of wood waste, and different types of recycled wood treatments on the physical and mechanical properties of recycled-wood particleboard. The most common adhesives used were UF and PF resins. However, other adhesive systems such as mixtures of liquefied wood binders and UF and a mix of pMDI and UF were also utilized by researchers. The treatments to which the wood particles and wood waste were subjected prior to particleboard manufacturing influence the mechanical and physical properties of the final products. Lykidis and Grigoriou [166] conducted a study to
Fig. 14 e The surface appearance of post-production particleboard.
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