Construction and mechanism analysis of flame retardant, energy storage and thermochromic composites based on natural lignin removal templates

To address the flammability of wood and to promote temperature visualization of wood in practical applications. In this study, a novel approach was developed to synthesize thermotropic phase change material (TPCM) by mixing decanoic acid (CA) and cinnamic acid (MA) with methyl red (MR), followed by vacuum impregnation into delignified wood (DW) to prepare thermotropic phase change wood (TWPCM). The surface of the wood was then modified with flame retardant to produce composites with integrated flame retardancy and thermochromic properties (IFR@TWPCMs). SEM and FT-IR showed good compatibility between these components, indicating the feasibility of this wood modification strategy. Differential scanning calorimetry (DSC) results showed that the phase transition temperature of TWPCM was lower than that of TPCM, and further surface flame retardant treatment could increase the phase transition temperature. Color responsiveness tests revealed that the color of the wood shifted from red to purple (ΔE > 25.0) with ambient temperature changes and that there was no detectable leakage was observed during thermal cycling. The tensile strength of the wood increased by 183.02% after flame retardant treatment. The LOI of IFR@TWPCMs increased to 27.3%, which enhanced the LOI by 23.53% compared to NW. In addition, compared to TWPCM, the conical calorimeter test showed a 55.7% and 25.6% reduction in heat release rate (HRR) and total heat release (THR), respectively. This study provides an innovative strategy for the preparation of multifunctional wood and shows broad application prospects in the field of smart homes, furniture materials and decoration.