Facile strategy of preparing excellently thermal-insulating and fire-safe building materials based on an aromatic Schiff base dicarboxylic acid without additional flame retardants

Developing excellently fire-safe and thermal-insulating building materials is a critical subject in the building sector. In this work, a novel aromatic Schiff base dicarboxylic acid (FN) was synthesized through a facile strategy to prepare high-performance rigid polyurethane foam (RPUF) composites with excellent thermal insulation and fire safety performance. The uniform dispersion of FN in polyether polyol improved the cellular structure of RPUF composites, which was conducive to increasing the thermal insulation of RPUF composites. Therefore, incorporating only 10 wt% FN into RPUF composite (RPUF/10FN) possessed the lowest wall temperature (51.9 degrees C) and room temperature (38.8 degrees C) with the lowest temperature growth rate under the continuous thermal radiation of the heat source among all samples in the small chamber test. Moreover, FN remarkably reduced the peak heat release rate, peak smoke production rate, and peak CO production rate of RPUF/10FN by 41.9%, 58.0%, and 59.6% without additional flame retardants, respectively, compared with those of pure RPUF. In addition, FN endowed RPUF/FN composites with better fire resistance and structural integrity compared with pure RPUF in the building facade fire test and fire protection test. The increased fire safety of RPUF/FN composites is due to the barrier effect of the formation of a dense and continuous char layer and the dilution effect of nonflammable gas generated by the thermal degradation of FN. Furthermore, FN enhanced the water contact angle of RPUF/FN composites from 112.2 degrees for pure RPUF to 120.8 degrees for RPUF/ 10FN, indicating that FN also enhanced the hydrophobicity of RPUF/FN composites. Therefore, the as-designed RPUF composites containing FN possessed a broad application prospect in the building field.