Thermal degradation of poly(lactide-co-propylene carbonate) measured by TG/FTIR and Py-GC/MS

Thermal degradation behaviors of poly(lactide-co-propylene carbonate)s (PLAPCs) with different PC contents were studied at various pyrolysis temperatures by the combination of thermo gravimetric analysis/Fourier transform infrared spectrometry (TG/FTIR) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) techniques. The activation energies of thermal degradation are calculated by Kissinger method. The experimental results indicate that increasing PC content in PLAPC chain lead to a decrease of maximum decomposition temperature. The activation energy of degradation increases with increasing PC content. The dominant degradation pathway is a backbiting ester interchange reaction involving OH chain ends of PLAPCs, resulting in the formation of cyclic oligomers. In addition, at a relative higher pyrolysis temperature, besides the major products propylene carbonate and lactide, small amounts of propenoic acid and acetaldehyde were also detected, showing a main intramolecular trans-esterification accompanied with chain scission decomposition mechanism.