Preparation of nano-SiO₂@TiO₂ reinforced bamboo-plastic composites and simulation analysis of performance for pallet application

Biomass composites are ever-increasing in agricultural engineering. This study aims to enhance the mechanical properties and aging resistance of bamboo-plastic composites (BPC), in order to realize the environmental friendliness and application of its pallet products. Firstly, three ratios of bamboo fiber (BF) and high-density polyethylene (HDPE) were used to prepare the BPC. Then mechanical property tests were conducted to determine the optimal ratio of BF to HDPE. Among them, nano-TiO₂ was widely used to enhance the performance of plant fiber/thermoplastic polymer composites, due to its chemical inertness, anti-aging, anti-bacterial properties, and non-toxic nature. An organic-inorganic co-modification was also employed to enhance the BPC properties for strong compatibility with bamboo fiber and plastic matrix. Nano-SiO₂ was coated onto nano-TiO₂ to prepare SiO₂@TiO₂ nanoparticles for the high dispersion and aging resistance of TiO₂. Nano-SiO₂@TiO₂ modified BPC (KH550-ST-BPC) was prepared using the silane coupling agent KH550 as a reinforcing agent by a spray coating. The properties were evaluated to compare the mechanical properties, SEM images, and UV aging properties of BPC before and after modification. In addition, ANSYS Workbench software was used to perform the finite element analysis of BPC integrated pallets before and after modification, in order to verify the application performance of reinforced BPC pallets. The results indicated: 1) The bending and tensile properties of BPC shared an increasing trend with the increase of bamboo fiber content. The optimal mechanical properties of BPC were obtained at a 5:5 mass ratio of BF to HDPE, with a 38.34% increase in the bending strength and a 62.19% increase in the bending modulus, compared with the 3:7 ratio. The tensile strength and modulus increased by 14.95% and 101.18%, respectively. SEM images revealed that there was a smoother interface for BPC55, which was better consistent with the mechanical test. 2) The bending and tensile strength of BPC were enhanced by 31.11% and 11.86%, respectively, in the modified nano KH550-SiO₂@TiO₂, while the bending and tensile modulus were enhanced by 52.27% and 21.92%, respectively. The interfacial gaps of modified BPC were significantly reduced in the SEM images, indicating the strong bonding between the bamboo fibers and HDPE. The KH550-SiO₂@TiO₂ was introduced to fill the interface gaps for the BPC compatibility, which was better consistent with the mechanical property test. 3) The surface morphology revealed that KH550-SiO₂@TiO₂ modified BPC maintained better color stability for the high resistance to UV aging. While the unmodified BPC showed significant color fading after 1 200 h UV irradiation aging. Colorimetric analysis confirmed that the color stability of KH550-ST-BPC was significantly better during UV aging, with a color aberration change value 77.79% lower than before. 4) Finite element analysis indicated that the modified BPC pallet exhibited the better-bending properties and load-bearing capacity, with a 27.36% reduction in the maximum deformation under the rated load and a 23.41% reduction under the ultimate load in stacking simulation. These research findings can provide a strong reference for the application of nano-SiO₂@TiO₂ reinforced BPC as logistics turnover units.