Phosphotungstic acid intercalated Zn,Al-layered double hydroxides/ nanocellulose based 3D lightweight foam thermal insulation materials

In this study, [PW₁₂O₄₀]³⁻ anions have been intercalated into Zn,Al-Layered Double Hydroxides(ZnAl-NO₃-LDHs) to synthesize ZnAl-PW₁₂O₄₀-LDHs by ion-exchange reaction. The chemical composition and structure were analyzed by XRD, FT-IR, ICP, and SEM. Then, the nanocellulose based 3D lightweight foam thermal insulation materials was prepared by ZnAl-PW₁₂O₄₀-LDHs and CNF compound with H₃BO₃. The TG showed that ZnAl-PW₁₂O₄₀- LDHs significantly reduced the maximum decomposition rate and increased the carbon residual rate at 800 °C, which indicated that ZnAl-PW₁₂O₄₀-LDHs can improve the oxidation resistance of CNF composite materials at high temperature.The fire resistance of different samples were evaluated by back temperature test and alcohol lamp flame test, CNF/50%ZnAl-PW₁₂O₄₀-LDHs /2%H₃BO₃ showed best thermal stability and flame-retardant properties, which can be contributed to the decomposition products of ZnAl-PW₁₂O₄₀-LDHs, acting both as phase flame retardant and condensed phase flame retardant. (paper)