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

Abstract Five commercial polymeric firestop materials (FS1–FS5) were characterized by thermogravimetric analysis (TGA) at three heating rates (5, 10, and $$40~\mathrm {K\,min^{-1}}$$ ) 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 $$\alpha (T)$$ , comparison against the mass-loss-rate signal revealed limited fidelity in predicting $$d\alpha /dT(T)$$ , indicating that agreement in $$\alpha (T)$$ 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 $$\alpha (T)$$ and $$d\alpha /dT(T)$$ 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 ( $$R^2 \gtrsim 0.93$$ ), supporting its use as a practical, simulation-ready kinetic description within a defined heating-rate window. Using parameters identified at $$\beta =10~\mathrm {K\,min^{-1}}$$ , EAE enabled cross-heating-rate prediction at 5 and $$40~\mathrm {K\,min^{-1}}$$ by changing only the heating rate, yielding improved agreement for both $$\alpha (T)$$ and, in most cases, $$d\alpha /dT(T)$$ .