Effect of accelerated weathering on pyrolysis kinetics and ignition characteristics of typical thermal insulation materials

Abstract

Thermal insulation materials are widely installed on external walls because of their excellent properties. However, thermal insulation materials are often exposed to air and sunlight as external facades fall off, which can lead to weathering and potential fire risk. Especially, weathering may cause changes in pyrolysis and combustion characteristics of thermal insulation materials, which is of great significance for understanding fire. To simulate real exposure conditions, typical thermal insulation materials (expanded polystyrene) were weathered by accelerated weathering for 25, 45, 90, 135 and 180 days. Pyrolysis characteristics of unweathered and weathered materials were researched by thermogravimetric analysis, Fourier transform infrared (FTIR) spectrometric technique and cone calorimeter experiments. The kinetic parameters were estimated and optimized using Coats-Redfern and Shuffled Complex Evolution methods. Subsequently, the correlation between weathering time and kinetic parameters was obtained. The functional groups were detected by FTIR. Finally, the ignition time was measured. The results showed that the color of materials changed and the chalking appeared as accelerated weathering increased. Activation energy decreased from 324.44 kJ/mol to 91.04 kJ/mol, and pre-exponential factors reduced from 52.31 lns−1 to 10.72 lns−1. The intensity of vibration bands was strengthened. Ignition time was shortened by 119 s, indicating that weathered EPS is more easily ignited.