Thermal depolymerization mechanisms of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Thermal degradation processes and decomposition mechanisms of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV) were investigated by using thermal gravity analysis(TGA), Gel permeation chromatography(GPC), elemental analyzer, pyrolysis-gas chromatography-mass spectrometry(Py GC-MS) and ~1H nuclear magnetic resonance(~1H NMR). The degradation activation energy was calculated via the dependence of residual mass on isothermal temperature.~1H NMR and Py GC-MS were used to investigate the chemical structure and component proportion of volatile gases and degradation residues which were produced by thermal decomposition, and to infer the process of macromolecular chain scission. Besides, the influence of the factors, such as outfield atmosphere, residual metal ions, on the degradation behaviors of PHBV was also studied. Finally, the PHBV thermal decomposition mechanisms were speculated on the basis of the degradation behaviors of molecular and chemical structure.