The thermal decomposition kinetics of the N,N′-bis(5,5-dimethyl-2-phospha-2-thio-1,3-di- oxan-2-yl)ethylenediamine (DPTDEDA) in air were studied by TG-DTG techniques. The kinetic parameters of the decomposition process for the title compound in the two main thermal decomposition steps were calculated through the Friedman and Flynn-Wall-Ozawa (FWO) methods and the thermal decomposition mechanism of DPTDEDA was also studied with the Coats-Redfern and Achar methods. The results show that the activation energies for the two main thermal decomposition steps are 128.03 and 92.59 kJ•mol^－1 with the Friedman method, 138.75 and 106.78 kJ•mol^－1 with the FWO method respectively. Although there are two main thermal decomposition steps for DPTDEDA in air, the thermal decomposition mechanism of DPTDEDA in the two steps are the same, i.e. f(α)=3/2(1－α)^4/3[(1－α)^－1/3－1]^－1.

Key words: N,N′-bis(5,5-dimethyl-2-phospha-2-thio-1,3-dioxan-2-yl)ethylenediamine, thermal decomposition kinetics, activation energy, mechanism