Interfacially enhanced fabric‐reinforced ceramifiable composites for superior fire and thermal insulation

Abstract Ceramifiable fire‐resistant composites are essential for high‐temperature applications, yet achieving both mechanical strength and thermal insulation remains challenging. This study reinforces boron phenolic resin/mullite‐aluminosilicate ceramifiable composites with polycrystalline mullite fibers (PMFs) and enhances fiber‐matrix adhesion through surface modification. Composites were fabricated using resin transfer molding and subjected to high‐temperature ceramification (1200°C). Results show that PMF‐based composites significantly improved bending strength (up to 351.58%), reduced thermal diffusivity (by 192.38%), and lowered thermal conductivity (by 158.27%). Flame ablation tests confirmed enhanced fire resistance, with PMF‐modified composites exhibiting back surface temperature reductions of up to 51.72°C after 60 s. X‐ray diffraction analysis revealed phase transformations stabilizing the ceramic network. These findings demonstrate that PMFs, particularly with surface modification, effectively enhance the mechanical and thermal performance of ceramifiable composites, offering promising applications in aerospace, construction, and fire protection systems. Highlights Polycrystalline mullite fibers enhance mechanical strength and fire resistance in ceramifiable composites. Surface modification strengthens fiber‐matrix bonding, reducing thermal diffusivity and conductivity. PMF‐reinforced composites maintain structural integrity with improved dimensional stability. Flame ablation tests confirm superior thermal insulation and delayed heat penetration.