Natural fiber composites are receiving more and more attention because of their greenness and low cost. Among natural fibers, bamboo is characterized by fast growth, a short cultivation period, high strength and good toughness, and is one of the strongest natural fibers in the world. A bamboo-fiber-reinforced polymer composite (BFRPC) has the characteristics of high mechanical strength, low density, degradability, etc. It has the industrial applicability comparable to metal materials, the same strong corrosion resistance as composites such as glass and carbon fibers, and the same immunity to electromagnetic interference and low thermal conductivity as natural materials. Its unidirectional specific strength and unidirectional specific modulus is higher than that of glass fiber, second only to the extremely high price of carbon fiber, which is playing an increasingly important role in the field of composite materials, and can be widely used in the fields of wind power, construction, aviation, automotive, medical care and so on. At present, it has been initially used in packaging, automotive and transportation fields, and is expected to replace petroleum-based plastics in various fields. In addition to their environmental protection and green production, they have excellent physical properties. This paper provides an overview of the mechanical properties of bamboo-fiber-reinforced thermoplastic composites and thermoset composites that have been developed so far, such as tensile strength, flexural properties and impact strength. In addition, the prospects of bamboo-fiber-reinforced thermoplastic composites for automotive, packaging and agricultural applications are presented.

With the enhancement of people’s environmental awareness, waterborne polyurethane (PU) paint—with its advantages of low release of volatile organic compounds (VOCs), low temperature flexibility, acid and alkali resistance, excellent solvent resistance and superior weather resistance—has made its application for wood furniture favored by the industry. However, due to its lower solid content and weak intermolecular force, the mechanical properties of waterborne PU paint are normally less than those of the traditional solvent-based polyurethane paint, which has become the key bottleneck restricting its wide applications. To this end, this study explores nanocellulose derived from biomass resources by the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidation method to reinforce and thus improve the mechanical properties of waterborne PU paint. Two methods of adding nanocellulose to waterborne PU—chemical addition and physical blending—are explored. Results show that, compared to the physical blending method, the chemical grafting method at 0.1 wt% nanocellulose addition results in the maximum improvement of the comprehensive properties of the PU coating. With this method, the tensile strength, elongation at break, hardness and abrasion resistance of the waterborne PU paint increase by up to 58.7%, ~55%, 6.9% and 3.45%, respectively, compared to the control PU; while the glossiness and surface drying time were hardly affected. Such exploration provides an effective way for wide applications of water PU in the wood industry and nanocellulose in waterborne wood coating.

Wood is susceptible to swelling deformation and decay fungi due to moisture adsorption that originates from the dynamic nanopores of the cell wall and the abundant hydroxyl groups in wood components. This study employed as a modifier maleic anhydride (MAn), with the help of acetone as solvent, to diffuse into the wood cell wall, bulk nanopores, and further chemically bond to the hydroxyl groups of wood components, reducing the numbers of free hydroxyl groups and weakening the diffusion of water molecules into the wood cell wall. The derived MAn-bulked wood, compared to the control wood, presented a reduction in water absorptivity (RWA) of ~23% as well as an anti-swelling efficiency (ASE) of ~39% after immersion in water for 228 h, and showed an improvement in decay resistance of 81.42% against white-rot fungus and 69.79% against brown-rot fungus, respectively. The method of combined cell wall bulking and hydroxyl group bonding could effectively improve the dimensional stability and decay resistance with lower doses of modifier, providing a new strategy for wood durability improvement.

Petroleum-based plastics, such as PP, PE, PVC, etc., have become an important source of environmental pollution due to their hard degradation, posing a serious threat to the human health. Isolating nanocellulose from abundant biomass waste resources and further integrating the nanocellulose into hydrophobic transparent film (i.e., nanopaper), to replace the traditional nondegradable plastic film, is of great significance for solving the problem of environmental pollution and achieving sustainable development of society. This study respectively extracted nanocellulose from the branches of Amorpha fruticosa Linn., wheat straw, and poplar residues via combined mechanical treatments of grinding and high-pressure homogenization. Among them, the nanocellulose derived from the Amorpha fruticosa has a finer structure, with diameter of about 10 nm and an aspect ratio of more than 500. With the nanocellulose as building block, we constructed hydrophilic nanopaper with high light transmittance (up to 90%) and high mechanical strength (tensile strength up to 110 MPa). After further hybridization by incorporating nano-silica into the nanopaper, followed by hydrophobic treatment, we built hydrophobic nanopaper with transmittance over 82% and a water contact angle of about 102° that could potentially replace transparent plastic film and has wide applications in food packaging, agricultural film, electronic device, and other fields.

Water-based polyurethane paint is widely used for wood furniture by virtue of the eco-friendliness, rich gloss, and flexible tailorability of its mechanical properties. However, its low solution (water or alcohol) resistance and poor hardness and wear resistance limit its application. The emerging graphene oxide has a high specific surface area and abundant functional groups with excellent mechanical properties, endowing it with great potential to modify waterborne polyurethane as a nanofiller. In this study, graphene oxide prepared by Hummers’ method is introduced in the chemosynthetic waterborne polyurethane through physical blending. The testing results demonstrate that the appropriate usage of graphene oxide at 0.1 wt% could obviously improve water absorption resistance and alcohol resistance, significantly enhancing the mechanical properties of waterborne polyurethane paint. The corresponding tensile strength, abrasion resistance, and pendulum hardness of the graphene oxide-modified paint film increase by 62.23%, 14.76%, and 12.7%, respectively, compared with the pristine paint film. Meanwhile, the composite paint film containing graphene oxide possesses superiority, including gloss, abrasion resistance, pendulum hardness, and tensile strength in contrast with the commercial paint. The use of graphene oxide to enhance the waterborne polyurethane possesses strong operability and practical value, and could provide useful reference for the modification of waterborne wood paint.

The aggregation morphology of anode materials plays a vital role in achieving high performance lithium-ion batteries. Herein, Co₃O₄ anode materials with different aggregation morphologies were successfully prepared by modulating the morphology of precursors with different cobalt sources by the mild coprecipitation method. The fabricated Co₃O₄ can be flower-like, spherical, irregular, and urchin-like. Detailed investigation on the electrochemical performance demonstrated that flower-like Co₃O₄ consisting of nanorods exhibited superior performance. The reversible capacity maintained 910.7 mAh·g⁻¹ at 500 mA·g⁻¹ and 717 mAh·g⁻¹ at 1000 mA·g⁻¹ after 500 cycles. The cyclic stability was greatly enhanced, with a capacity retention rate of 92.7% at 500 mA·g⁻¹ and 78.27% at 1000 mA·g⁻¹ after 500 cycles. Electrochemical performance in long-term storage and high temperature conditions was still excellent. The unique aggregation morphology of flower-like Co₃O₄ yielded a reduction of charge-transfer resistance and stabilization of electrode structure compared with other aggregation morphologies.