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Bamboo units used for manufacturing engineered bamboo products are typically processed by breaking and planing, resulting in products with high glue content, substantial costs, and adverse environmental impacts. To address these issues, a simple and effective approach for processing standard bamboo units, based on the natural form and structure of bamboo, is proposed and tested in this study. More specifically, bamboo splits were dried at 0.05 MPa pressure and 140 °C for about 2.5 h in a pressurizing device. After drying, the bamboo splits each formed an equal-arc shaped bamboo split (EASB) in which the inner and outer radii were roughly equal. The EASB unit represents a double breakthrough of a high material utilization rate (as high as 80%) and low damage to bamboo. Additionally, the appropriate drying technique improves the dimensional stability and retains the excellent mechanical properties of natural bamboo. This work demonstrates the concept of "natural form inspired design," and the EASB provides a basis for wider applications of sustainable engineered bamboo products. [Display omitted] • An integrated process of bamboo split radian adjustment and drying is presented. • The bamboo unit developed herein retains bamboo's natural structure and texture. • The bamboo utilization rate of this bamboo unit is as high as 80%. • The bamboo unit retains the excellent mechanical properties of bamboo. [ABSTRACT FROM AUTHOR]

Fined processing is one of the ways to utilize bamboo efficiently. In this study, fine surface sanding was carried out to treat the bamboo surface. The wax layer and pith film that affected the bonding in bamboo skin (BS) and bamboo pith ring (BP) were removed, and the bamboo could form an excellent adhesive force. The fine gluing process model was constructed based on the single factor and response surface model. The maximum shear strength of the adhesive layer was 11.08 MPa obtained by and at temperature, time, and pressure of 143 ℃, 25 min, and 1.75 MPa from the response surface model, respectively. Based on the data of the single factor and response surface experiment, a fine deep learning model for on-demand production is constructed. The model can predict the shear strength of the adhesive layer under given gluing parameters. After glued, the glue penetrated the parenchyma cells in the BS and the stone cells on the BP, forming a glue nail and glue interlocking structure; the bonded with cellulose, hemicellulose, and lignin in bamboo to create a chemical binding force. In addition, sanding reduced the mass and thickness by 1.68 % and 0.43 %, increasing the rate of bamboo drying. • Bamboo skin and bamboo pith ring are glued by fine sanding. • The model of fine gluing process was established. • The bonding mechanism of bamboo skin and bamboo pith ring is expounded. [ABSTRACT FROM AUTHOR]

Gaining a comprehensive understanding of the bonding characteristics of fibers and parenchyma cells in the gluing process is essential for understanding the formation of the bamboo gluing force and optimizing the bonding properties of bamboo. In this study, based on the bonding strength measured by gluing, a new in-situ dynamic observation method is employed to assess the bonding characteristics of fibers and parenchyma cells and examine their contribution to the bonding strength in bamboo. The glue primarily interacts with parenchyma cells and the lateral fibers of the fiber sheath during gluing. Glue nails and cross-linked interlocking structures are formed due to fibers and parenchyma cells' deformation during gluing. When compared with fibers, parenchyma cells have a complete reaction with glue, although at a slower rate. The correlation analysis indicated that the influence of cell deformation on bonding strength was more significant than that of chemical reactions, and the impact of parenchyma cells outweighed that of fibers. When the ratio of fiber and parenchyma cells is 37 % and 63 % in the bonding interface of Moso bamboo, which exhibits a higher bonding strength, this finding shed light on the contributions of fiber and parenchyma cells to bonding strength. [Display omitted] • The gluing process of bamboo cells was observed in-situ. • The deformation of cell on bonding strength is greater than chemical reaction. • The contribution of parenchyma cells to bonding strength is greater than fibers. [ABSTRACT FROM AUTHOR]