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AFM phase images at 500 nm of cellulose microfibrils with different pretreatments. (a) Untreated and air-dried, (b) treated and air-dried, (c) untreated and freeze-dried, and (d) treated and freeze-dried.
Source publication
Fibers of primary cell walls of Ci bamboo (Neosinocalamus affinis) were analyzed with an atomic force microscope (AFM) to determine the arrangement of microfibril aggregates and the effect of pretreatments (ultrasonic treatment and different drying methods) on the arrangement and diameter of microfibril aggregates and the cell wall topography. The...
Contexts in source publication
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... between microfibril aggregates. AFM phase images of bamboo fibers with differ- ent pretreatments are shown in Fig 6. In spite of all images clearly showing a similar randomly interwoven structure, the microfibril aggregates presented differently, especially concerning the spacing among microfibril aggregates. ...
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... with that in freeze-dried samples, the microfibril aggregates in air-dried samples pressed each other much closer, especially in the samples treated by ultrasound. In addition, for air-dried samples (Fig 6a and b), the microfibril aggregates in fibers treated by ultrasound pressed each other tighter than that in untreated samples, which meant smaller spacing among microfibril aggre- gates treated. However, the phenomenon shown in freeze-dried samples (Fig 6c and d) was in contrast with the air-dried samples. ...
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... addition, for air-dried samples (Fig 6a and b), the microfibril aggregates in fibers treated by ultrasound pressed each other tighter than that in untreated samples, which meant smaller spacing among microfibril aggre- gates treated. However, the phenomenon shown in freeze-dried samples (Fig 6c and d) was in contrast with the air-dried samples. Namely, the spaces between microfibril aggregates in treated samples were larger than those in untreated ones. ...
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... there was no gross change on structure induced by freeze-dried during sample preparations ( Kirby et al 1996). Therefore, there were many differences of spac- ing among microfibril aggregates between air- dried and freeze-dried samples (Fig 6). ...
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... a consequence, the ultrasonic treatment achieved an intensive mechanical fibrillation, iso- lated more noncellulosic polysaccharides from the microfibrils, and induced more gaps among the cellulose microfibril aggregates. In air-dried samples after ultrasonic treatment, the microfibril aggregates overlapped tightly for loss of water and shrinkage (Fig 6b). However, the microfibril aggregates in treated and freeze-dried samples were arranged loosely for losing more noncellu- losic polysaccharides, which resulted in larger gaps among cellulose microfibril aggregates (Fig 6d). ...
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... air-dried samples after ultrasonic treatment, the microfibril aggregates overlapped tightly for loss of water and shrinkage (Fig 6b). However, the microfibril aggregates in treated and freeze-dried samples were arranged loosely for losing more noncellu- losic polysaccharides, which resulted in larger gaps among cellulose microfibril aggregates (Fig 6d). ...
Citations
... Given that multicell tubes have been demonstrated to have outstanding energy absorption performance, the multicell tube W2W shown in Fig. 3 [27] was selected as the reference to design a new series of multicell tubes. Specifically, the patterns in the cross section of the square bamboo shown in Fig. 2 [28] were utilized to replace the pattern of the reference tube, resulting in a new series of multicell tubes. The cross section and corresponding geometric parameters of the reference and BMT structures are illustrated in Fig. 3. Thickness is considered a crucial factor that influences the behavior of thin-walled structures, so it was selected as a design vari- able. ...
... Cross section of (a) a bamboo culm; (b) the vascular bundle[28]. ...
In this research, a new series of bioinspired multicell tubes was designed based on the cross-sectional patterns of square bamboo and optimized to enhance energy absorption under multiple loads. A data-driven model was proposed to efficiently design and optimize structures with improved energy absorption performance under axial and oblique crushing scenarios simultaneously. Furthermore, the influence of design parameters on energy absorption performance was extensively investigated. Results demonstrated that the energy absorption performance of the optimized structures under axial and oblique loads was considerably improved compared with the performance of the original and reference tubes. Under axial load, the highest enhancements in specific energy absorption (SEA) and crush force efficiency (CFE) were 133.58 % and 20.21 %, respectively. Under oblique load, the improvements in SEA and CFE were 108.78 % and 23.65 %, respectively. This study introduced an efficient data-driven model for designing and optimizing energy absorption structures under multiple loads. This optimized structure shows great potential for use in energy absorption devices.
... In recent years, microscopic imaging and spectral characterization methods have been used in nanostructure and chemical composition analyses of cell walls of plant fibers like wood fibers [11][12][13][14][15][16], bamboo fibers [17][18][19][20][21][22], and cotton fibers [23,24]. Chen et al. [25] characterized the aggregation of microfibrils in the cross-section of thin-wall cells using the atomic force microscopy (AFM) technique. ...
... The primary wall and epidermal layer were relatively thin, the secondary wall was relatively thick, and the connection between the primary wall and epidermal layer with the secondary wall was the darkest. In the modulus image, cellulose microfibril is the bright part, and the interstitial space between the non-cellulose polysaccharide matrix and microfibril is the dark part, because this matrix is significantly less elastic and harder than the microfibril [29,[45][46][47][48]. Chen et al. [17,25] concluded that from the inside of the cell wall to the outside of the cell wall, the density of cellulose microfibril aggregates was unevenly distributed. The test data indicated that the number of cellulose microfibrillar aggregates in the boundary position was significantly higher than that inside the three layers, and the arrangement was dense. ...
In this study, the microstructure and mechanical properties of poplar (Populus tomentosa) catkin fibers (PCFs) were investigated using field emission scanning electron microscope, atomic force microscopy (AFM), X-ray diffraction, and nanoindentation methods. Experimental results indicated that PCFs had a thin-wall cell structure with a large cell lumen and the hollow part of the cell wall took up 80 percent of the whole cell wall. The average diameters of the fiber and cell lumen, and the cell wall thickness were 5.2, 4.2, and 0.5 µm, respectively. The crystallinity of fibers was 32%. The AFM images showed that the orientation of microfibrils in cell walls was irregular and their average diameters were almost between 20.6–20.8 nm after being treated with 2 and 5 wt.% potassium hydroxide (KOH), respectively. According to the test of nanoindentation, the average longitudinal-reduced elastic modulus of the PCF S2 layer was 5.28 GPa and the hardness was 0.25 GPa.
