2-羟基和4-羟基-3,5-二硝基吡啶铅盐的热行为、分解机理、非等温分解反应动力学及其在推进剂中的应用

Thermal Behavior, Decomposition Mechanism and Non-isothermal Decomposition Reaction Kinetics of Lead Salts of 2-Hydroxy-3,5-dinitropyridine and 4-Hydroxy-3,5-dinitropyridine and Their Application in Propellant

在程序升温条件下 ,用DSC ,TG ,慢速裂解 /傅里叶红外 ,研究了 2 羟基 3 ,5 二硝基吡啶铅盐 ( 2HDNPPb)和 4 羟基 3 ,5 二硝基吡啶铅盐 ( 4HDNPPb)的热行为、机理和动力学参数 ,提出了它们的热分解机理 ,计算了热爆炸临界温度 ,考察了它们对RDX改性双基推进剂的催化效果 .结果表明 :2HDNPPb和 4HDNPPb主放热分解反应的表观活化能和指前因子值分别为 2 5 2 .3 4kJ·mol-1,10 19.3 0 s-1和 187.3 9kJ·mol-1,10 13 .74s-1.由加热速率 β→ 0的DSC曲线的初始温度 (Te)和峰温 (Tp)算得 2HDNPPb和 4HDNPPb的热爆炸临界温度值分别为 3 2 7.64 ,3 3 6.5 7和 3 2 3 .90 ,3 3 3 .96℃ .2HDNPPb的热稳定性优于4HDNPPb .0 .1MPa时 ,它们的放热分解过程动力学方程可表示为 : 对 2HDNPPb dα/dT =10 2 0 .48( 1-α) [-ln( 1-α) ] 3 /5e-3 .0 3 51× 10 4 /T 对 4HDNPPb dα/dT =10 15.0 0 ( 1-α) [-ln( 1-α) ] 2 /3 e-2 .2 53 9× 10 4 /T对含RDX改性双基推进剂 ,它们都具有催化燃烧和降低压力指数的作用 .2HDNPPb的催化效果明显优于 4HDNPPb .

The thermal behavior, mechanism and kinetic parameters of the exothermic decomposition reaction of lead salts of 2-hydroxy-3,5-dinitropyridine (2HDNPPb) and 4-hydroxy-3,5-dinitropyridine (4HDNPPb) in a temperature-programmed mode have been investigated by means of DSC, TG-DTG and lower rate thermolysis/FT-IR. Their reaction mechanisms were proposed. Their critical temperatures of thermal explosion were calculated. The catalytic effects of 2HDNPPb and 4HDNPPb on the composite modified double base (RDX-CMDB) propellant containing RDX were studied. The results show that the apparent activation energy and pre-exponential constant of the major exothermic decomposition reaction of 2HDNPPb and 4HDNPPb, at 0.1 MPa, are 252.34 kj (.) mol(-1) and 10(19.30) s(-1), 187.39 kJ (.) mol(-1) and 10(13.74) s(-1), respectively. The critical temperatures of thermal explosion of 2HDNPPb and 4HDNPPb obtained from the onset temperature (T-e) and the peak temperature (T-p) are 327.64 degreesC and 336.57 degreesC 323.90 degreesC and 333.96 degreesC, respectively. The thermal stability of 2HDNPPb is better than that of 4HDNPPb. Their kinetic equations of the major exothermic decomposition process at 0.1 MPa can be expressed as: for 2HDNPPb dalpha/dT = 10(20.48)(1 - a) [ - ln(1 - alpha)](3/5)e (-3.0351 x 104/T) for 4HDNPPb dalpha/d T = 10(15.00)(1 - a) [ - ln(1 - alpha](2/3) e (-2.2539 x104/T) 2HDNPPb and 4HDNPPb possess better catalytic effect and ability to reduce pressure exponent for RDX-CMDB propellant. In comparison with 4HDNPPb, 2HDNPPb has the higher catalytic efficiency. The positions of the hydroxyl group in the molecules were the principal factor affecting the thermal stability and the catalysis activity of 2HDNPPb and 4HDNPPb.