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Figure 2. Optical microscope images of ( a ) bamboo fibers and ( b ) enzyme-treatment bamboo fibers.
Fine fiber content (%)
Fiber length (mm)
Type
Length weighted Arithmetic mean
Width (μm) Coarseness (mg/m) Curl Index (%)
Length Area
BFs
1.534
1.021 0.334
23.6 20.3
0.2175 0.4296
16.8
66.9 90.3
27.21 74.40
EBFs 0.405
5.9
Table 1. Physical properties of BFs and EBFs.
Figure 3. Atomic force microscope images of ( a ) CNFs; ( b ) CNF length and ( c ) CNF diameter.
tained the characteristic peaks representing cellulose, such as the stretching vibration peak of –OH at 3425 cm −1 , the stretching vibration peak of –CH at 2900 cm −1 , and the bending vibration peak of –CH at 1375 cm −144 . Compared with BFs, the absorption peaks of EBFs and CNFs were enhanced. The stretching vibration peak of –CO at 1030 cm −1 was enhanced, indicating that some of the cellulose of EBFs was hydrolyzed, and the content of primary hydroxyl groups increased 45 . The enhancement of the peak at 897 cm −1 was due to the breakage of some β-glycosidic bonds and the destruction of cellulose molecular chain 46 . In summary, EBFs and CNFs still maintained the basic chemical structure of cellulose. X-ray diffraction analysis. Figure 5 shows the X-ray diffraction (XRD) patterns of BFs, EBFs, and CNFs. The diffraction overlapped peak at about 16° correspond to the (1–10)/(110) cellulose crystallographic plane, and the diffraction peaks of 22° and 34.5° correspond to the (200) and (004) cellulose crystallographic plane, respec- tively, which belong to the typical cellulose type I crystal 47,48 . Compared with BFs, the crystallinity of EBFs increased from 53.08% to 67.26%, which was due to the amorphous region of cellulose being destroyed by enzymes 49 . Compared with BEFs, the crystallinity of CNFs decreased slightly to 63.63%, which indicated that high-pressure homogenization has a certain destructive effect on the crystalline region of cellulose.
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(2022) 12:16148 |
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