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journal of materials research and technology 2022;20:4630 e 4658
shells exhibited lower TS and WA than wood-based particleboard. In a study by Wechsler et al. [121], macadamia ( Macadamia integrifolia ) nut shells and castor ( Rı´cinos communis ) oil-based resin was used to produce particleboard. Even with a much higher density (987 kg/m 3 ), the MOR of macadamia particle- board was lower than pine particleboard (691 kg/m 3 ) by half, while the MOE value was almost three-times lower. However, macadamia particleboard displayed better IB, TS, and WA than pine particleboard. Lower absorption and water-induced swelling of macadamia particleboard could be attributed to the superior moisture resistance of macadamia nut shells. Cellulose is responsible for the strength and stiffness of the agro-fibers. Therefore, lower MOR and MOE are expected for macadamia shell particleboard as macadamia shell has lower cellulose content (30%) than pine wood (44%). Owing to their superior moisture resistance, macadamia nut shell/castor oil particleboard has the potential for use in humid environments. Barbu et al. [50] investigated the feasibility of using walnut and hazelnut shells in particleboard manufacturing. The au- thors fabricated various panels using walnut or hazelnut shells bonded with MUF or PU resin and a target density of 1000kg/m 3 (Fig. 11). MOR and MOE values were 40 e 50%lower for MUF resin bonded nutshell boards compared to spruce particleboard and 65% higher when PU adhesive was used. When compared to spruce particleboard, the developed composites had significantly higher WA and TS values, as well as close-to-zero free formaldehyde content, meeting the re- quirements of the E0 emission grade ( 2.5 mg/100 g) for both walnut and hazelnut shell raw materials, and of the super E0 category ( 1.5 mg/100 g) when PU resin was used EN ISO 12460-5 [122]. The possibility of manufacturing particleboard from groundnut shell and rice husk wastes, bound with a modified adhesive system, was evaluated by Akinyemi et al. [123]. The authors investigated the effects of the addition of different levels of groundnut shells and rice husks in the composition of the panels, i.e. 30 e 70,70 e 30,50 e 50%, and 100% for each of the waste materials. The developed composites exhibited signifi- cantly deteriorated dimensional stability values, failing to
Fig. 9 e Surface appearance of stalk-based particleboard (own photo).
counterparts. Fine particles are easy to press, resulting in higher density and compacter board and correspondingly better performance. Particleboard produced displayed good thermal conductivity with values ranging between 0.075 and 0.079 W/mK. Except for MOE, MOR, and TS, the particleboard made from sunflower seed husk failed to meet the minimum requirements for particleboard for general use (type P1) and moisture resistance particleboard (type P3). It is therefore recommended to be used for furniture components or other structural applications that are not subject to load-bearing. Shells of almond, walnut, macadamia, and peachnut have been utilized in particleboard production (Table 7). Pirayesh et al. [39] produced walnut ( Juglans regia L.) shell- and almond ( Prunus amygdalus L.) shell-based particleboard bonded with UF resin. The results revealed that the 100% walnut shell particleboard had the lowest MOR, MOE, and IB values. Markedly, particleboard made from 100% almond shell exhibited better mechanical properties than walnut shell particleboard. However, both types of particleboard were inferior compared to particleboard made from hornbeam ( Carpinus betulus L.) and beech ( Fagus orientalis L.) wood. Interestingly, particleboard made from walnut and almond
Table 5 e Physical and mechanical properties of particleboard manufactured from selected plant stalks. Raw Materials Adhesive type Adhesive (%) Density (kg/m 3 ) MOR (MPa) MOE (MPa) IB (MPa) TS, 24h (%) WA, 24h (%)
References
Rapeseed stalk Chili pepper stalk Tomato stalk Sunflower stalk
UF UF UF
8 8
684 701 950 600 600 600 600 600 600 600 600 600 600 600 600
11.7 12.2 20.5
1798 1856
0.47 0.61
50.3 43.9 18.1 ~35 ~30 ~41 ~39 ~29 ~27 ~41 ~40 ~43 ~33 ~66 ~57
90.4
[77] [46] [68] [72]
82
16
1123.9 0.91
N/A ~122
MDI MDI
4 6 8
~10.2 ~1600 ~12.2 ~1840
~0.5 ~0.6
~92
UF UF
~8
~1600
~0.32
~122 ~108
12
~10.2 ~1800 ~10.4 ~1840 ~11.8 ~1920
~0.4
Topinambour stalk
MDI MDI
4 6 8
~0.55 ~0.62 ~0.42 ~0.54 ~0.54 ~0.62 ~0.38 ~0.42
~78 ~64
UF UF
~8.4 ~9.8
~1780 ~1840
~134 ~122
12
Cup-plant stalk
MDI MDI
4 6 8
~12.2 ~2040
~92 ~80
~12 ~9.6 ~11
~2100 ~1720 ~1900
UF UF
~152 ~130
12
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