Modelling Pyrolysis Kinetics of Five Commercial Firestop Polymers: Isoconversional Analysis and Effective-Activation-Energy Parameterization

Five commercial polymeric firestop materials (FS1–FS5) were characterized by thermogravimetric analysis (TGA) at three heating rates (5, 10, and 40~ K\,min⁻¹ ) to quantify their multistep pyrolysis kinetics. Model-free isoconversional methods (Friedman, Kissinger–Akahira–Sunose (KAS), and Flynn–Wall–Ozawa (FWO)) were first applied to estimate conversion-dependent activation energies and reconstruct the experimental response. Although these approaches captured the overall conversion histories α (T) , comparison against the mass-loss-rate signal revealed limited fidelity in predicting dα /dT(T) , indicating that agreement in α (T) alone can overstate predictive quality for complex, additive-containing formulations. To address this gap, a simulation-oriented effective-activation-energy (EAE) representation was introduced and calibrated by fitting both α (T) and dα /dT(T) simultaneously. In validation against synthetic data and published TGA datasets for PMMA and pine wood, the EAE approach achieved consistently high accuracy across heating rates ( R² 0.93 ), supporting its use as a practical, simulation-ready kinetic description within a defined heating-rate window. Using parameters identified at β =10~ K\,min⁻¹ , EAE enabled cross-heating-rate prediction at 5 and 40~ K\,min⁻¹ by changing only the heating rate, yielding improved agreement for both α (T) and, in most cases, dα /dT(T) .