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journal of materials research and technology 2022;20:4630 e 4658
regardless of the type of liquefied wood waste binders used. The slight reduction in MOR and MOE in the particleboard bonded with liquefied wood powder binder was attributed to the relatively low density of tested samples (629 kg/m 3 ) compared to the density of other samples of approximately 650kg/m 3 . Liquefied wood waste binders decreased the TS and WA of all samples. Nuryawan et al. [184] studied the effect of liquefied adhesive made from oil palm stem particleboard properties and reported similar findings. Thus, it can be concluded that all raw materials used to make liquefied wood waste binders have a favorable impact on the TS and WA of the boards. The properties of recycled-wood particleboard also depend on the type of recycled wood waste used. Azambuja et al. [178] carried out research to determine the properties of particle- board made from different types of wood waste, i.e., medium density fiberboard (MDF), medium-density particleboard (MDP), plywood, and timber residues. The authors observed that the particleboard made from recycled timber residue displayed the highest MOR, MOE, and IB values. This result could be associated with the higher slenderness ratio of the recycled timber particles, resulting in better bending strength [29]. On the other hand, particleboard produced from MDF recorded the lowest MOR, MOE, and IB values. As a reference, the MOR, MOE, and IB of the control panels made from fresh particles from pine logs were 8 N/mm 2 , 1378 N/mm 2 , and 0.91N/mm 2 , respectively. Regarding the IB of all samples, only particleboard made from recycled MDF particles did not meet the requirement stated in EN 312. To utilize other types of recycled wood waste despite the reduction of mechanical
performance they induced, the authors suggested that those wastes be used as the inner or core layer in the production of layered particleboard. The study of other processing param- eters is required to improve the mechanical performance of recycled wood particleboard further. Besides the type of wood waste, the ratio of wood waste to fresh wood particles also affects the properties of the board manufactured. This prompted I zdinsky´ et al. [180] to evaluate the physical and mechanical properties of particleboard made from different wood wastes with different ratios. The parti- cleboard was produced with particles from the fresh spruce log and particles from recycled hardboard, MDF board, pallet, old furniture (R1), and recycled faulty particleboard (R2). The authors observed that particleboard produced from 100% fresh spruce particles exhibited the highest MOR, MOE, and IB values. The MOR, MOE, and IB of particleboard specimens made from a mixture of fresh wood particles and recycled wood products showed a slight decrease. However, the physical properties such as TS and WA of the specimen made from recycled wood, both R1, and R2, demonstrated major improvement. The authors concluded that although the addition of R1 improved the TS and WA of the specimens, the improvement was considered non-significant (r 2 , 0.0001 e 0.09). On the other hand, the addition of R2 showed a significant positive effect (r 2 , 0.63 e 0.72) on the TS and WA. Similar results were also reported by Azambuja et al. [178]. The results might be attributed to the slower water movement into the particleboard produced with fresh spruce and R2 particles. The existence of cured UF adhesive molecules on the surfaces of R2 particles obstructs the water movement.
Fig. 16 e Modulus of rupture (MOR) e density chart for particleboard (651 e 1000kg/m 3 ) made with agricultural biomass and conventional wood.
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