High-performance bamboo-/wood-based structural or building materials have attracted more and more attention as a kind of renewable carbon cycle materials. However, biomass materials are prone to mildew, poor surface hydrophobicity and bad dimensional stability when used outdoors, which seriously restricts their applications. In this work, nano-Fe3O4/bamboo bundles/phenolic resin oriented recombination ternary composite boards are successfully fabricated by directional recombination and hot-pressing of nano-Fe3O4 decorated bamboo bundles. Through the combination of iron/alkali liquid step-by-step impregnation and nanocrystalline in-situ crystallization, nano-Fe3O4 particles are pre-modified on bamboo bundle surface with characteristics of directional arrangement along the fiber direction. The obtained samples which are named as T1, T2 and T3 with increasing nano-Fe3O4 loading content, exhibit enhanced hydrophobicity along with varied physico-mechanical properties. Among them, T2 possesses the best compressive properties, dimensional stability, and mildew resistance, being attributed to the role from nano-Fe3O4 in bridging and enhancing the interactions between bamboo bundles and phenolic resin through ion-dipole interaction between iron atoms and electron-rich oxygen atoms. Furthermore, on the basis of maintaining the unique pore-line staggered structural characteristics of bamboo, the construction of micro continuous equivalent circuit network of the ternary composites is realized, endowing their efficient electromagnetic dissipation capacity. Our work provides systematic experimental and theoretical support for the application of high-performance outdoor recombinant bamboo board in specific scenes.

Nano-Fe3O4/bamboo bundles/phenolic resin oriented recombination ternary composite with enhanced multiple functions

With the rapid growth of China’s economy and people’s high-level pursuit of life, eco-friendly materials are gradually used in home decoration, furniture and construction industries. Compared to wood, bamboo has its own advantages such as large strength, good toughness, and great abrasion resistance when it is applied as a material to structural engineering or home decor. However, bamboo also has several limitations, for example, a small diameter, a longitudinal difference in diameter, thin and hollow walls, and a disposition to corrosion and cracking. Therefore, there is an urgent need to develop a new efficient and high-value utilization technology of bamboo. “Bamboo flattening” is a kind of high-efficiency utilization technology adopted to construct flattened bamboo boards from bamboo tubes or pre-softened arc-shaped bamboo sheets. Prior to flattening, pretreatments are requested, including softening, outer layer removal, and inner layer removal. For the bamboo tubes, penetrating grooves are requested to be created which are supposed to be widened during the saturated steam heat treatment and are conducive for the tubes to enter into the flattening machine. Moreover, tapered, rectangular or “V”-shaped protrusions nails with uniform dispersions, or diamond-shaped line grooves with a width, depth and spacing of 1.5–2.0 mm, 2.0–4.0 mm and 5.0–8.0 mm are always created to release the generated internal stress during the flattening processes. For the arc-shaped bamboo slices, a non-notched flattening method is introduced with a machine equipped with the unfolding rolling component, the flattening component, and the reverse roller component. There are no grooves, nails or guide lines on the inside surface of the obtained bamboo board. It is worth mentioning that all boards obtained should be treated by cooling, shaping and drying. Bamboo flattening technology can increase the utilization rate of bamboo resource from the original 30–55 %, reduce the amount of adhesive by 30 %, and increase the added value by more than 20 %. Herein, the achievements in bamboo flattening technology based on published papers and patents are described, along with their underlying physicochemical mechanisms.

Bamboo flattening technique: a literature and patent review

Bamboo is now widely used in construction, papermaking, textile, furniture and other fields because of its renewable, fast-growing, high-strength, high-yield and easy processing. However, compared with wood, bamboo and bamboo products are more vulnerable to damage by fungi and pests. An effective and eco-friendly method is urgently needed to improve their physical and chemical properties, decay resistance and anti-mildew properties, and hydrophobic properties. Here, bamboo was heated with methyl silicone oil. The effect of different temperatures (140 °C–200 °C) and different times (2 h–6 h) on the properties of bamboo was studied systematically, including chemical composition, physical and mechanical properties, surface wettability, decay resistance and anti-mildew property. No starch granules were observed inside the parenchymal cell lumen of bamboo specimen heat treated at 200 °C for 6 h. And with the increase of heat treatment temperature and time, the content of cellulose and hemicellulose decreases gradually while relative content of lignin increases due to its better thermal stability. Accordingly, the surface wettability decreases due to the changes of the surface functional groups and micro-morphologies. Under the condition of oil heat treatment at 160 °C for 2 h, the compressive strength parallel to grain of bamboo samples reach the maximum of 109.52 MPa. With further increase of heating temperature, the corresponding compressive strength decreases. The resulted bending strength and MOE both display similar changing trend. However, the optimal parameter is at 180 °C for 2 h, with the highest bending strength and MOE values of 142.42 MPa and 12,373.00 MPa, respectively. Finally, the decay resistance and anti-mildew property are dramatically enhanced with increased heat treatment temperature and time. All the corresponding changing mechanisms are investigated in depth and in detail. Our results provide comprehensive process parameters and micro-mechanism for the performance of oil heat treatment of bamboo, which can be used to guide the actual production.

/pdf/the-effect-of-oil-heat-treatment-on-biological-mechanical-4emeh9lyk6.pdf

The effect of oil heat treatment on biological, mechanical and physical properties of bamboo

Bamboo fiber has attracted a lot of interest due to its high specific strength and renewability. Unidirectional long bamboo fiber reinforcing is essential to fully realize its strength. The reinforcing efficiency can also be affected by the physical and chemical structure of bamboo fibers. Therefore, this study reviews the cell wall structure of the bamboo fiber. The alternately arranged structure with thin and thick layers contributes substantially to the mechanical strength of the bamboo fiber. In addition, this study evaluates the mechanical properties, water absorption, and flame retardancy of polymeric and cementitious composites reinforced with long bamboo fibers. Thermoset polymer-based bamboo fiber composites typically show higher mechanical strength than thermoplastic-based fiber composites. Chemical treatment and flame retardant can significantly enhance the hydrophobicity and flame retardancy of fiber composites, respectively. Because of its superior interface performance, the short bamboo fiber has a greater reinforcing effect in cement mortar than in concrete. This study can serve as a reference for further investigations on bamboo fiber/bundle reinforced composites and promote their applications. 

Structural and mechanical properties of bamboo fiber bundle and fiber/bundle reinforced composites: A review

Bamboo heat treatments and their effects on bamboo properties

https://www.techscience.com/jrm/v9n5/41556/pdf

Fabrication of Crack-Free Flattened Bamboo and Its Macro-/MicroMorphological and Mechanical Properties

Artificial nanomotors are nanoscale machines capable of converting surrounding other energy into mechanical motion and thus entering the tissues and cells of organisms. They hold great potential to revolutionize the diagnosis and treatment of diseases by actively targeting the lesion location, though there are many new challenges that arise with decreasing the size to nanoscale. This review summarizes and comments on the state‐of‐the‐art artificial nanomotors with advantages and limitations. It starts with the fabrication methods, including common physical vapor deposition and colloidal chemistry methods, followed by the locomotion characterization and motion manipulation. Then, the in vitro and in vivo biomedical applications are introduced in detail. The challenges and future prospects are discussed at the end.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/idm2.12021

Artificial nanomotors: Fabrication, locomotion characterization, motion manipulation, and biomedical applications

Comparison of the fabrication process and macro and micro properties of two types of crack-free, flatten bamboo board

Injectable chemically powered nanomotors may revolutionize biomedical technologies, but to date, it is a challenge for them to move autonomously in the blood circulation system and they are too large in size to break through the biological barriers therein. Herein, we report a general scalable colloidal chemistry synthesis approach for the fabrication of ultrasmall urease-powered Janus nanomotors (UPJNMs) that have a size (100-30 nm) meeting the requirement to break through the biological barriers in the blood circulation system and can efficiently move in body fluids with only endogenous urea as fuel. In our protocol, the two hemispheroid surfaces of eccentric Au-polystyrene nanoparticles are stepwise grafted with poly(ethylene glycol) brushes and ureases via selective etching and chemical coupling, respectively, forming the UPJNMs. The UPJNMs have lasting powerful mobility with ionic tolerance and positive chemotaxis, while they are able to be dispersed steadily and self-propelled in real body fluids, as well as demonstrate good biosafety and a long circulation time in the blood circulation system of mice. Thus, the as-prepared UPJNMs are promising as an active theranostics nanosystem for future biomedical applications.

Xiaomeng Hao

Papers

Fabrication of Crack-Free Flattened Bamboo and Its Macro-/MicroMorphological and Mechanical Properties

The effect of oil heat treatment on biological, mechanical and physical properties of bamboo

Artificial nanomotors: Fabrication, locomotion characterization, motion manipulation, and biomedical applications

Comparison of the fabrication process and macro and micro properties of two types of crack-free, flatten bamboo board

Ultrasmall Enzyme-Powered Janus Nanomotor Working in Blood Circulation System.