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

• A simplified out-wall insulation RPU was self-synthesized and characterized by SEM, TG.
• Its thermal degradation mechanisms in non-oxidative/oxidative atmosphere are proposed.
• Changes of functional groups in RPU solid phase were recorded by in-situ FTIR.
• Volatile products in helium and air were identified by TG-FITR-GC/MS.

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.