ABSTRACT The inherent porous structure of cotton stalk surfaces presents significant challenges for its use as a raw material in particleboard production, resulting in vulnerabilities such as water‐induced cracking and deformation, limited weather resistance, and inadequate mechanical strength. In this study, 3‐aminopropyltriethoxysilane was employed as a bridging agent to successfully incorporate spherical silica into the microporous structure of cotton straw via covalent bonding for the first time. The modified cotton stalk undergoes a crosslinking reaction with isocyanate adhesive (MDI) under high‐temperature and high‐pressure conditions, forming a thermosetting composite material with a multidimensional crosslinked network structure anchored by urethane (–NH–CO–O–) and urea (–NHCONH–) linkages. The plugging effect of SiO 2 effectively inhibited the penetration of the adhesive into the pores of the cotton stalk, and the utilization rate of the adhesive was significantly improved. The tensile strength, flexural strength, and impact strength can reach 40.6, 47.8 MPa, and 2.38 KJ/m 2 , respectively. The silica microspheres effectively filled the internal pores of the board, substantially inhibiting water ingress and reducing the 24‐h water absorption and thickness swelling rates to 5.32% and 3.23%, respectively. The uniform dispersion of silica on both the surface and interior of the board functions as a physical barrier, effectively reflecting UV light and mitigating heat transfer to the core. The total heat release (THR) and total smoke production (TSP) of the flame‐retardant modified particleboard SiO 2 –FFPB/APP were reduced by 31% and 29.9%, respectively, compared to FFPB, reaching only 44.7 MJ/m 2 and 12.9 m 2 . Furthermore, the limiting oxygen index (LOI) increased to 32.2%, demonstrating significantly enhanced flame retardancy. This work realizes the high‐quality recycling of cotton straw and expands the practical applications of particleboard by improving its performance in various aspects, which can be used as a building material with significant industrialization potential.
Di et al. (Sun,) studied this question.