Thermal decomposition properties of cross-linked polycarbonate derived from carbon dioxide, propylene oxide and pyromellitic dianhydride

Poly(propylene carbonate pyromellitic dianhydride) (PPCPD) was synthesized from carbon dioxide (CO 2 ), propylene oxide (PO) and pyromellitic dianhydride (PD) using Zn–Fe(III) double metal cyanide (DMC) as a catalyst. The thermal properties of PPCPD were investigated with thermogravimetric analysis (TGA) and differential thermal gravity (DTG). TGA and DTG curves of PPCPD indicate that the decomposition process of PPCPD includes 2 stages: the chain scission decomposition stage (1st decomposition stage) and the chain unzipping decomposition stage (2nd decomposition stage). According to the Flynn–Wall–Ozawa method, the average apparent activation energies ( E a ) of 1st and 2nd decomposition stages are 98.95   kJ/mol and 150.39   kJ/mol, respectively. The result shows that the chain unzipping decomposition is difficult compared with the chain scission decomposition in the process of PPCPD decomposition. Furthermore, according to the Phadnis–Deshpande model, the degradation kinetic models of 1st and 2nd decomposition stages of PPCPD follow a phase boundary mechanism and a 3-dimensional diffusion mechanism, respectively.