Performance Enhancement of the Poplar Wood Composites Biomimetic Mineralized by CaCO₃

Inspired by the natural matrix-mediated biomineralization, wood composites were prepared by vacuum impregnation using the gel effect of sodium alginate (SA) on calcium ions, which improved the mechanical properties, flame retardant, and smoke suppression properties of the wood composites. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed that the SA inducer had promoted the orderly deposition and directional crystallization of calcium carbonate (CaCO₃) inside the wood cell walls and intercellular spaces. The density and weight gain rate of the biomimetic mineralized wood showed that CaCO₃ effectively adhered to the interior of wood with SA as an inducer. The compressive and flexural strengths were 15.65% and 37.66% higher than those of the control, respectively. Thermogravimetric analysis (TG) proved that SA alleviated the thermal decomposition and complete combustion of the mineralized wood and improved the thermal stability. Microcalorimetry (MCC) and cone calorimetry (CONE) analyses revealed that the maximum heat release rate (HRR), total heat release (THR), and the total smoke production (TSP) rate of the mineralized wood was reduced by 59.51%, 48.52%, and 51.67%, respectively, compared with those of the control. This research demonstrates the in situ synthesis of CaCO₃ within the cellular microstructure of the poplar which is using it as a biotemplate. With the enhancement of the flame retardant property and others, the wood composite biomimetic mineralized materials modified by CaCO₃ and SA could be utilized more widely in the construction industry or other fields.