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

摘要

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 (Ea) 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.