FULL PAPER * E-mail: yanglibit@163.com; Tel./Fax: 0086-010-68913818 Received June 30, 2010; revised August 23, 2010; accepted November 5, 2010. Project supported by the State Key Laboratory of Explosion Science and Technology (Nos. YBKT10-05, ZDKT10-01b). Chin. J. Chem. 2011, 29, 411—414 © 2011 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 411 Researches on Thermal Decomposition Kinetics of Composite Modified Double-base Propellants Tang, Zhan a (汤崭) Ren, Yan a (任雁) Yang, Li* ,a (杨利) Zhang, Tonglai a (张同来) Qiao, Xiaojing a (乔小晶) Zhang, Jianguo a (张建国) Zhou, Zunning a (周遵宁) Zhao, Fengqi b (赵凤起) Dang, Yongzhan b (党永战) Xu, Siyu b (徐司雨) Yi, Jianhua b (仪建华) a State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China b National Key Laboratory of Science and Technology on Combustion and Explosion, Xi'an Modern Chemistry Research Institute, Xi'an, Shaanxi 710065, China The thermal decomposition kinetics of composite modified double-base (CMDB) propellants with a series of contents of hexogeon (RDX) was investigated by using parameters of T eo , T i , T p , T f , T b , T a , E, lg A and ΔH, which were obtained from using a CDR-4P differential scanning calorimeter (DSC) and Perkin-Elmer Pyris 1 thermogra- vimetric analyzer (TG) analyses with heating rates of 5, 10, 15 and 20 K/min. Reliable activation energy was calculated using Flynn-Wall-Ozawa method before analyzing the thermal decomposition mechanism. TG-DTG curves were treated with Malek method in order to obtain the reaction mechanisms. The obtained results show that the thermal decomposition mechanisms with the conversion from 0.2 to 0.4 was f(α) ＝1/2α, and with the conversion from 0.5 to 0.7 was f(α)＝(1/4)(1－α)[－ln(1－α)] －3 . Keywords thermal stability, decomposition machenism, DSC, TG, Malek method Introduction Stability studies of energetic materials by differential scanning calorimetery (DSC) and thermogravimetry (TG) have been applied for long time. T eo , T i , T p , T f , T b , T a , E, lg A and ΔH are very important parameters in de- termining the stability of propellants. 1-10 In order to ex- plore the thermal decomposition mechanisms of com- posite modified double-base propellant and obtain ki- netic parameters, such as apparent activation energy (E), the isoconversional methods 11-14 and the Malek method 15-18 were employed according to suggestions of ICTAC (International Confederation of Thermal Analy- sis and Calorimetry). 19,20 The supposition of decomposi- tion mechanism function is not needed for Flynn- Wall-Ozawa method and the computation is simpler than other methods. Reliable description on the decom- position of a substance can not be made with other ap- proaches over the range of experimental temperatures except the Malek method. Therefore, the kinetic pa- rameters of thermal stability were investigated by means of DSC and TG methods with a series of heating rates 5, 10, 15 and 20 K/min to obtain the thermal decomposi- tion mechanisms of modified double-base propellants. Experimental The powdered samples were prepared in the RDX contents of 20%, 30%, 40%, 50% and 60%, and they are named as MDBR-1, MDBR-2, MDBR-3, MDBR-4 and MDBR-5 correspondingly. The initial data needed for calculating all the kinetic parameters were obtained by using a CDR-4P differen- tial scanning calorimeter with an aluminium cell. The conditions of the DSC analyses were: sample mass about 0.5 mg; heating rates in 5, 10, 15 and 20 K/min respectively; atmosphere, static air; reference sample, α-Al 2 O 3 . Thermogravimetric analyses were carried out on a Perkin-Elmer Pyris 1 thermogravimetric analyzer oper- ating at heating rates of 5, 10, 15 and 20 K/min in a flow of dry oxygen-free nitrogen at 20 mL/min. Results and discussions Effect of heating rates and RDX contents The DSC curves with heating rate 10 K/min of sam- ples MDBR-1 and MDBR-2 are shown in Figure 1, and MDBR-3 to MDBR-5 in Figure 2.