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journal of materials research and technology 2022;20:4630 e 4658
Fig. 7 e Classification of non-wood biomass used in particleboard manufacturing.
might be attributed to the chili pepper stalk ' s higher lignin content than the rapeseed stalk (25.4% vs 15.3%, respectively). Lignin, with relatively higher hydrophobicity, is the main contributor to the less water accessibility of plants [101]. Nourbakhsh et al. [102] also found that agricultural biomass with lower lignin content tends to have higher water uptake. Both particleboards made from chili pepper stalk and rape- seed stalk achieved the minimum requirements for MOR, MOE, and IB, according to the Korean Standard KS F 3104 for PB type 8.0 [KS F 3104 [103]]. However, a certain amount of wood particles or a higher amount of resin could be employed to attain a more satisfactory outcome [77]. High holocellulose content in tobacco stalks (~68%) is the main reason for its inferior dimensional stability. Apart from that, its anatomical properties, such as long fiber (1.23 mm) with large cell lumen width (15.4 m m), also contributed to its dimensional instability compared to wood particles [67]. Markedly, particleboard made from tobacco stalks has better termite resistance than particleboard made from P. falcataria L. Nielsen, as shown by Acda and Cabangon [67]. After expo- sureto Coptotermes gestroi Wasmann, particleboard made from 100% P. falcataria experienced 43% weight loss compared to only 1.5% in particleboard made from 100% tobacco stalk. Weight loss caused by termites decreased as the proportion of tobacco stalks increased. Incorporating 25% tobacco stalks has already led to significant resistance against termites. Never- theless, 50% of tobacco stalks are needed for the underground field exposure test to protect from subterranean termites, Macrotermes gilvus Hagen. 100% weight loss was recorded in the particleboard made from 100% P. falcataria, while only 1.32% weight loss was observed for particleboard made with 100% tobacco stalks, indicating its high resistance against
et al. [92] manufactured rapeseed straw in five densities (450 e 650 kg/m 3 ). With increasing density, the particleboard ' s bending strength (MOR), modulus of elasticity (MOE), and in- ternal bond (IB) value increased. The particleboard met the requirements of the P7 type, i.e., boards with increased load- carrying capacity intended for use in humid conditions, ac- cording to EN 312 [93]. One of the most significant issues with cereal straws as a raw material for particleboard manufacturing is their seasonal availability, resulting in inconsistent supply throughout the year. White mustard ( Sinapis alba L.), harvested at different times than cereals, is an excellent substitute. White mustard is a high-yielding, fast- growing crop, and its straw can be used as a feedstock in particleboard production [92].
4.2.
Stalk-based particleboard
Chili pepper [46], tobacco [67], cotton [94,95], sunflower [96], sorghum [78], Miscanthus [97], rapeseed [77], tomato [68], kenaf [98,99], topinambour [100], and cup-plant [72] have all used plant stalks as raw materials for particleboard produc- tion. Their chemical composition varies among agricultural biomass and significantly impacts the physical and mechan- ical performance of the resulting particleboard. Fig. 9 shows the surface appearance of stalk-based particleboard. The physical and mechanical properties of particleboard made from some selected plant stalks are given in Table 5. Under the same processing parameters, i.e. UF resin content 8%, pressing temperature 170 C, and pressing time 4 min, particleboard made from chili pepper stalk [46] had lower thickness swelling (TS) and water absorption (WA) values compared to that of its rapeseed stalk counterpart [77]. This
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