Materials 2022 , 15 , 4542
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Table4. Fiber characteristics of alternative materials as compared with wood fibers.
Material
Fiber Characteristics
Density (gcm − 3 )
Length (mm)
Diameter ( μ m)
References [48,76–78,80]
0.3–7.2
10–45
1.4–1.5
Wood
NWLM Bamboo
1.5–4.4 10–65
7–27 5–38
0.6–1.1
[48,76]
Flax
1.4
[67]
Hemp Kenaf
5–55
1–5
1.4–1.5
[48,76,81] [48,67,82]
3.55–5.5 0.81–1.05
12–37
1.4
Miscanthus
11.8–16.7
-
[79]
Sisal
0.8–8
7–47
1.45
[50,67]
Grow care residues
n.a.
n.a.
n.a.
Harvest residues Banana wood Canola stalks Corn stalks Cotton stalks Oil palm wood Pineapple leaves
0.17 1.22 1.22 0.84 0.66
13.6
1.35
[50,67]
28
- -
[83] [84]
24.3 23.9
1.45–1.85 0.7–1.55
[83,85]
29.6–35.3
[50,67,86]
-
20–80
1.526
[87,88] [89,90] [84,92] [93,94] [91]
Rice stalks
0.4–3.4
4–16 13.8 21.5
0.38
Sorghum stalks Sunflower stalks
1.8
-
1.18
0.154
Tomato stalks Wheat stalks Barley stalks
0.83–1.13 1.1–1.13
13.24–17.26
0.58
11.9–15.3
- -
[95] [56] [81] [33] [56] [96] [67]
0.7–3.1
7–24
Process residues Coconut coir
20–150 0.05–0.8 0.5–1.5 0.84–2.38 0.89–0.99
10–460
1.15
Coffee husks Cornhusks Durian peel
15
- -
10–20
170–447 19.1–25
1.15–1.31 0.7–1.55
Oil palm fruit husks
Ricehusks
-
170
1.16 0.99
[97,98] [97,99]
Sugarcane bagasse
1.59
20.96
There is limited data available on fiber dimensions from grow care residues. Ntalos and Grigoriou [54] reported that the anatomical and chemical components of the grow care residues correspond to those of the main plant. In comparison with wood and NWLMs, the harvest residues have noticeably shorter fibers, as their fiber lengths are mainly ranged from 1.1 mm for wheat stalks [95] to 1.8 mm for sorghum stalks [91], which is about half of wood fibers. The fiber diameter is, on average, approximately 30% smaller than wood [83,84,92]. The fiber morphology of harvest residues could, therefore, have a negative impact on the bending properties. As with the chemical composition, the fiber dimensions of process residues are also varied due to growth and processing conditions and some individual settings. However, since these materials are collected after the processing of the crops, their fibers are generally shorter than wood fibers [100]. The length of fibers from different husks, such as coffee husks or oil palm fruit husks, ranges from 0.05 to 0.99 mm [33,56,67]. With 15 μ m, 10–20 μ m, and 19.1–25 μ m, the fiber diameters of coffee, corn, and oil palm fruit husks is roughly half that of wood fibers [33,56,67]. Due to the clearly shorter dimensions, the length- width ratio of process residues differs from wood fibers, as they have a cubic form. For example, coconut coir and rice husks have with their large fiber diameters of 10–460 μ mand approximately 170 μ m in length relatively short fiber geometries [81,98]. The integration of process residues in wood-based panels could therefore be a challenge.
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