Thermal degradation study of pure rigid polyurethane in oxidative and non-oxidative atmospheres

With a modelled building insulation rigid polyurethane foam (RPU) based on polymeric 4,4′-diphenylmethane diisocyanate and polyether polyol, thermal degradation mechanisms of RPU in oxidative and non-oxidative atmospheres were systematically investigated. In the condensed phase, results of thermogravimetric analysis (TGA) and in-situ Fourier transforms infrared (FTIR) spectroscopy in N₂ and air showed that, presence of oxygen began to accelerate the thermal degradation at 120 °C, whereas the communal reactions occurred 30-70 °C delay in N₂. In the gas phase, thermogravimetry- Fourier transform infrared spectroscopy coupled with gas chromatography and mass spectrometry (TG-FITR-GC/MS) was used and more than 20 characteristic products reflecting the structure and reaction routes were identified. With fruitful information of solid and gaseous products, it can be adequately deduced the mechanism of RPU thermal degradation at elevated temperatures in different atmospheres.