To evaluate the stability, heat-resistance ability and thermal safety of MNPP(1H,4H-3-methyl-6-nitro-pyrazolo[4,3-c]pyrazole), CNPP (1H,4H-3-carboxy-6 -nitro-pyrazolo[4,3-c]pyrazole), DNPP (1H,4H-3,6-dinitro-pyrazolo [4,3-c] pyrazole), the theoretical investigation on MNPP, CNPP and DNPP was performed by the DFT-B3LYP/6-31G level using Gaussian 09W program. The theoretical density (ρ) of the compounds was obtained by quantum chemical method. The Kamlet-Jacobs formulas were employed to calculate the detonation properties including the detonation velocity (D) and pressure (P). Their thermal behaviors were investigated by Differential Scanning Calorimetry (DSC), Thermogravimetry-Derivative Thermogravimetry (TG-DTG) and in-situ cell thermolysis/Rapid-Scan Fourier Transform Infrared Spectroscopy (RSFT-IR). Results show that (1) using critical temperature of thermal explosion, free energy of activation of decomposition reaction and self-accelerating decomposition temperature as criterions, the thermal stability, heat resistance ability and thermal safety of the three compounds decrease in the order of DNPP > MNPP >CNPP, but using energy gap and total energy as criterions, the thermal stability decreases in the order of DNPP > CNPP > MNPP, therefore, DNPP is the most stable compound among the three compounds; (2) Among of the three compounds, DNPP possesses the maximum theoretical density (1.80 g•cm-3), the fastest detonation velocity (8.49 km•s-1) and the highest detonation pressure (31.96 GPa), suggesting that DNPP has good detonation properties and potential use in energetic material.

Jiao-Qiang Zhang, Ning-Ning Zhao, Hong-Yu Zhou, Hai-Xia Ma, Hong-Xu Gao, Bo-Zhou Wang and Rong-Zu Hu