A novel multi-stage pyrolysis kinetics model for predicting thermal decomposition of quartz/phenolic composites in multi-atmospheres

Quartz/phenolic composites undergo complex charring ablation when subjected to aerodynamic loading. Quantitatively characterizing their pyrolysis mechanisms across various atmospheres is essential for developing high-fidelity ablation models. A multi-stage pyrolysis kinetics model was established for quartz/phenolic composites under multiple atmospheres, integrated with thermogravimetric (TG) data obtained at various heating rates. The pyrolysis process was decoupled into multiple discrete stages based on the thermal degradation mechanisms of individual components. By incorporating the weight proportion of each stage, a comprehensive kinetics model covering the full temperature range was developed using a hybrid approach of model-free and model-fitting methods. The proposed model effectively predicts the TG behavior of polymer-based materials under arbitrary temperatures and oxygen partial pressures, facilitating the analysis of their thermal response characteristics. Furthermore, key parameters including the degree of pyrolysis and gas evolution rates can be obtained, providing critical data support for simulating the ablation and heat transfer behavior of composite materials in extreme environments.