Flame-Retardant Wood Composite Based on Carboxylated Cellulose Fibers and Algal Polysaccharides

To address increasingly pressing ecological, energy, and resource challenges, there is an urgent need to develop and utilize renewable resources, in particular the exploitation of polymeric materials in marine and terrestrial organisms. This study focuses on a bottom-up preparation process to achieve uniform mechanical strength in all dimensions. Micron and nanoscale oxidized cellulose fibers were prepared through etching and oxidation techniques. Cross-linking metal ions with oxidized celluloses and alginate polysaccharides established a 3D cross-linking system. The flame retardancy of composite woods was evaluated using the limiting oxygen index (LOI) and cone calorimetry (CONE). With an LOI value of 30%, the composite wood exhibited a remarkable increase in fire resistance capability, surpassing the LOI value of natural wood (18%) by a significant margin. Furthermore, the composite wood exhibited a considerably lower minimum total heat release (THR) (5.35 MJ m–2) compared to natural wood (12.82 MJ m–2). To conduct a qualitative analysis of the molecular structures found in the pyrolysis products, the researchers employed pyrolysis gas chromatography/mass spectrometry (PY-GC/MS). The study’s findings indicated that carbon dioxide emerges as the primary product. Consequently, these findings suggest that the composite wood exhibits outstanding flame-retardant properties, rendering it suitable for diverse applications in everyday environments.