4642
journal of materials research and technology 2022;20:4630 e 4658
Table 8 e Physical and mechanical properties of particleboard manufactured from selected leaves. Raw Materials Adhesive type Adhesive (%) Density (kg/m 3 ) MOR (MPa) MOE (MPa) IB (MPa) TS, 24h (%)
WA, 24h (%)
References
Sycamore ( Platusorientalis ) leaves Waste tea ( Camellia sinensis ) leaves
MDI MDI
4 4 8
600 700 650
15.92 1958 0.57 16.63 2021 0.63
18.05 16.12
34.2
[132]
32.72
UF
13
1200 0.346
~18
~40
[126]
Sugarcane leaves
UF
12
510
N/A N/A N/A
52.17
187.2
[134]
invasive plant in the wetland. Jose tall wheatgrass is an introduced tall, cool-season, salt-tolerant, perennial bunch- grass planted for grazing, haying, or erosion control. Vetiver grass, also called khus, is a perennial bunchgrass that shares many morphological characteristics with other fragrant grasses, such as lemongrass. The roots of vetiver grass are oil- bearing and can be used in perfumes. Clippings of perennial ryegrass, together with Eucalyptus camaldulensis Dehn. wood particles have been used by Nemli et al. [74] in the production of UF-bonded particleboard. The particleboard made from 100% grass clippings had the lowest mechanical strength. Grass clippings could only be used as a substitution for wood in a relatively small amount. Eucalyptus particleboard substituting 6% and 13% grass clippings were reported to achieve desired mechanical properties for general uses and interior fitments and improved dimensional stabil- ity. Grass has a waxy layer on the surface; therefore, water- based UF resin is deemed unsuitable to be used as a binder during the production of grass-based particleboard. Pan- ichnava and Nimityongskul [135] reported that polyvinyl acetate-based adhesive is a more suitable binder for vetiver grass than urea-formaldehyde and corn starch. Although the cost of polyvinyl acetate-based adhesive is slightly higher than that of corn starch-based adhesive, it is, however, still 40% cheaper than bagasse boards. Meanwhile, pMDI also performed better in bonding vetiver grass particleboard than formaldehyde-based resins (UF and PF) [136]. pMDI-bonded Saline Jose tall wheatgrass particleboard also exhibited bet- ter properties than its UF-bonded counterparts [137]. Isocyanate-based adhesives such as MDI (diphenylmethane diisocyanate), pMDI or polyurethane (PUR), PVA (polyvinyl alcohol), and PVAc (polyvinyl acetate), and acryl-based
adhesives are suitable options [138,139]. Fig. 12 shows the image of the reed canary grass particleboard. Bamboo is a perennial woody grass often confused with trees due to its tree-like appearance and woody features. Bamboo shares similar characteristics with all types of grass as its internodal stem are hollow. Unlike trees, bamboo does not have a vascular cambium layer or meristem cells at the top of its culm. In addition, bamboo has no bark [140]. All these characteristics make bamboo grass . Information on the physical and mechanical properties of particleboard manu- factured of different bamboo species, bound with 10% UF resin, is presented in Table 9. Generally, the properties of the particleboard made of bamboo did not differ greatly as its chemical composition did not vary much among species. The density of the boards is the main factor that affects the per- formance of bamboo particleboard. MOR and MOE values increased along with increasing density. In contrast, the dimensional stability was inversely affected by increasing board density.
4.7.
Palm-based particleboard
The carbohydrate content of oil palm trunk (OPT) is high, while the lignin content is low [145]. The cellulose content of OPT and empty fruit bunch (EFB) is comparable to that of softwood and hardwood. In contrast, oil-palm frond has a higher cellulose content than softwood and hardwood. How- ever, oil palm biomasses have lower lignin content compared to softwood and hardwood species [146]. For many years, oil palm trunk has been recognized as a lignocellulosic material suitable for producing value-added composite panels. Due to the high proportion of soft parenchyma tissues in the central region of the trunk, only the outer part of the oil palm trunk is traditionally used during the lumber production process [147]. According to Bakar et al. [148], the unused inner part can ac- count for up to 70% of total weight and is frequently consid- ered waste. These wastes have the potential to be an excellent material for particleboard production. Particleboard made of OPF, OPT, and EFB is shown in Fig. 13. Because oil palm trunk has a lower density than rubber- wood, using it as the core layer of particleboard could result in a higher compaction ratio, according to Lee et al. [9]. In theory, the higher the compaction ratio, the lower the density of wood materials. High compaction improves particleboard perfor- mance [149]. However, in the study conducted by Lee et al. [150], this was not the case. The core layer of the three-layer particleboard was the oil palm trunk, and the surface layers were rubberwood. Based on their findings, the authors concluded that particleboard made entirely of rubberwood
Fig. 12 e Reed canary grass particleboard by Trischler et al. [139], licensed under Creative Commons Attribution- NonCommercial 4.0 International License.
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