Research Information System
Polymer Composites, 2025 (SCI-Expanded)
The aerospace industry is seeking a replacement of toxic phenolics to use in ablative materials. One of the most promising candidates is polybenzoxazine materials because of their extreme heat resistance and less toxicity. This study introduces thermal and mechanical properties improvement of polybenzoxazine materials by manufacturing a silica fiber-reinforced polybenzoxazine composite with the incorporation of submicron sized alumina particles. Polybenzoxazine composites with varying alumina amounts are examined in terms of their ablation performance by oxyacetylene test. One of the lowest mass ablation rates of fiber-reinforced ablative composites in the literature, 0.0284 g/s, has been achieved in the oxyacetylene test by the addition of only 3 wt.% alumina particles into the composite. This addition reduced the ablation rate by ~15% compared to neat composite indicating increased insulation performance for alumina added polybenzoxazine composite. The thermally degraded microstructures of the char layers are examined by SEM and elemental mapping to explain the degradation mechanism and the increased performance. The thermal degradation reactions of the polybenzoxazine composites were investigated by thermogravimetric analysis. Also, the flexural and interlaminar shear strengths of the composites were successfully risen ~11% and ~27%, respectively. This study proves that polybenzoxazine materials are favorable candidates for ablation/insulation materials to be used in thermal protection systems.