Waterborne acrylic coatings, the largest market share of predominant environmentally friendly coatings, face limitations in their extensive application due to their flammability. The flame-retardant properties of the coatings could be significantly enhanced by incorporate inorganic flame retardants. However, inorganic flame retardants tend to aggregate and unevenly disperse in waterborne acrylic coatings, causing a substantial decrease in flame retardancy. In this work, sodium silicate was utilized as a flame retardant, with urea and melamine serving as modifiers and synergistic agents. This combination resulted in the preparation of a sodium silicate/urea/melamine ternary synergistic waterborne acrylic flame-retardant coating. This coating was applied to the surface of poplar veneer to create flame-retardant poplar veneer. Subsequently, various instruments, including a scanning electron microscope (SEM), a limiting oxygen index meter (LOI), a thermogravimetric analyzer (TG), and a cone calorimeter (CONE), were employed to investigate the relevant properties and mechanisms of both the flame-retardant coating and poplar veneer. The results demonstrated that the sodium silicate/urea/melamine ternary synergistic flame retardant did not exhibit aggregation and could be uniformly dispersed in waterborne acrylic coatings. The physical and mechanical properties of the ternary synergistic flame-retardant poplar veneer coating were satisfactory. Melamine and urea, acting as modifiers, not only greatly enhanced the dispersibility of sodium silicate in waterborne acrylic coatings, but also assisted in the formation of a silicon-containing char layer through the generation of nitrogen, achieving ternary synergistic flame retardancy. In conclusion, this work explores a novel method to efficiently and uniformly disperse inorganic flame retardants in organic coatings. It significantly improves the dispersibility and uniformity of inorganic flame retardants in organic polymers, thereby substantially enhancing the flame-retardant performance of coatings. This work provides a theoretical basis for the research and application of new flame-retardant coatings in the field of chemistry and materials.

The incompatibility between inorganic flame retardants and organic acrylic coatings represents a significant challenge that requires resolution. This work selected environmentally friendly organic aqueous acrylic coatings as the substrate, sodium silicate hydrate as the inorganic flame retardant, and melamine cyanurate (MCA) as the flame-retardant modifier and the flame-retardant co-modifier, with the objective of improving the dispersion and flame-retardant properties of sodium silicate hydrate in the aqueous acrylic coatings. Subsequently, the sodium silicate/MCA/waterborne acrylic acid flame-retardant coating was prepared. The flame-retardant treatment was then applied to poplar veneer in order to create a flame-retardant poplar veneer. The dispersion of the flame-retardant coating was characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX), and X-ray diffractometry (XRD). Furthermore, the flame-retardant properties of the flame-retardant poplar veneer were analyzed by thermogravimetry (TG), limiting oxygen index (LOI), and cone calorimeter. The results demonstrated that the MCA-modified sodium silicate flame retardant was well dispersed in aqueous acrylic coatings. The results of the flame-retardant properties of the poplar veneer indicated that the ignition time of the 9% flame retardant-treated poplar veneer was increased by 122.7%, the limiting oxygen index value was increased by 43.0%, and the peak heat release rate (pHRR), the peak total heat release rate (pTHR), and the peak mass loss rate were decreased by 19.9%, 10.8%, and 27.2%, respectively, in comparison to the non-flame retardant-treated poplar veneer. Furthermore, the residual char mass increased by 14.4%, and the residual char exhibited enhanced thickness, density, and regularity. The results demonstrated that MCA was an effective promoter of sodium silicate dispersion in acrylic coatings. Furthermore, the sodium silicate/MCA/waterborne acrylic flame-retardant coating significantly enhance the flame retardancy of wood, and its flame retardant mechanism was consistent with the synergistic silicone–nitrogen expansion flame-retardant mechanism. This work presents a novel approach to enhancing the dispersion of inorganic flame retardants in organic coatings, offering a valuable contribution to the advancement of research and application in the domains of innovative flame retardant coatings and flame retardant wood.

In this study, moso bamboo was used as a raw material. To increase the plasticity of bamboo to achieve a greater softening effect, the softening method of hydrothermal treatment was used. Hardness and the flexural elastic modulus were used as the evaluation indices, and the crystallinity and main functional groups of the softened bamboo were analysed using X-ray diffraction and Fourier-transform infrared spectroscopy. Combined with the examination of timber colour, micromorphology, bending strength, and nanomechanical tests, our analysis showed the effects of the hydrothermal treatment on bamboo. The results showed that the hardness and flexural moduli of bamboo decreased with the increase in hydrothermal treatment temperature. However, cracking occurred after 3.5 and 4 h of treatment at 180 °C and 190 °C. This indicated that the softening effect was most pronounced when the treatment temperature and time were 180 ℃ and 3 h, respectively. The cellulose crystallinity of bamboo increased and then decreased with the increase in treatment temperature. Cracks were produced in the cell structure, starch locally disappeared, and the hardness and the elasticity modulus of the thin-walled bamboo cells first increased and then decreased with the increase in treatment temperature.

This study investigated the effects of thermal modification treatment on flattened bamboo lumber by using temperature (180 °C, 190 °C, 200 °C) and duration (2, 3, 4 h) as experimental variables. The physicochemical properties, crystallinity, bending deformation, chemical composition, and microstructural evolution of the material before and after treatment were systematically analyzed using universal mechanical testing, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and nanoindentation. This comprehensive approach aimed to achieve high-performance flattened bamboo lumber. The results revealed that thermal modification significantly reduced the flexural modulus of elasticity and hardness of the flattened bamboo lumber, which reached their minimum values of 4479 MPa and 786.71 N, under the treatment at 190 °C/3 h. Conversely, it enhanced the longitudinal compressive strength of flattened bamboo lumber, achieving a maximum value of 57.28 MPa at 180 °C/2 h. At the microscale, the nanomechanical strength decreased under 190–200 °C treatments, accompanied by a tighter cell arrangement and evident shrinkage and deformation of the parenchyma cells. Dimensional stability tests combined with FTIR and crystallinity analyses demonstrated a reduction in the number of hydrophilic groups and improved dimensional stability after thermal modification. Notably, the material treated at 200 °C for 4 h retained its dimensional stability and exhibited no deformation.

Betula alnoides was used as a test material to study the effect of ammonia fumigation treatment on wood color and chemical composition. The effects of concentration, temperature, and duration of ammonia fumigation on wood color were studied. The properties of the material were studied using contact angle measurements, X-ray diffraction, Fourier-transform infrared spectroscopy, and dynamic thermomechanical analysis. In general, the color difference of the wood increased with the concentration of ammonia used in the fumigation process, treatment temperature, and treatment duration. After ammonia fumigation treatment, the chemical composition of hydroxyl and carboxyl groups in the wood was reduced. We concluded that ammonia fumigation treatment decreased material wettability and dynamic mechanical rigidity and increased the degree of crystallinity in wood.

Using 1–8 years bamboo as materials, the content of different chemical constituent was tested, and the reactive oxygen species (ROS) free radicals produced from laccase treated bamboo were detected by electron spin-resonance (ESR) spectroscope. The wet-process particleboard was made from laccase-treated bamboo by hot pressing and board mechanical properties including internal bond strength (IB), modulus of rupture (MOR) and thickness swelling (TS) after 2-hours water absorption were tested under different conditions. Results showed that laccase mainly catalyze the bamboo components and improved the bonding strength of laccase-treated boards. By ESR measurement on each single component such as milled bamboo lignin, xylan and pore cotton treated with laccase, it was proved that laccase helped the degradation of bamboo lignin to produce ROS free radicals and could not catalyze the oxidation of cellulose and hemicelluloses. A logarithmic function relationship was found between board mechanical properties and ROS free radical level. It is optimal to using 5-year-old bamboo for high efficient utilization. The laccase treatment improves the activity of bamboo particles participating in self-adhesion reaction.