Thermal degradation mechanism of poly(butylene carbonate)

Thermal degradation mechanism of poly(butylene carbonate) (PBC) was elucidated by means of thermogravimetric analysis (TGA), 1H nuclear magnetic resonance (1H NMR) and pyrolysis-gas chromatography mass spectrometry (Py-GC/MS). The results indicated that there are three main pathways for the thermal degradation of PBC, including unzipping, β-H transfer and decarboxylation reactions. The unzipping reaction can be facilely induced at low temperature of 200 °C, and all of the three reactions occur at high temperature above 300 °C. TGA results suggested the thermal stability order: hydroxyl-terminated PBC < acetyl-terminated PBC < methyl carbonate terminated PBC. The hydroxyl end group can induce the unzipping reaction, while methyl carbonate chain-end depresses the occurrence of it.