Effects of Lead Complex-Based BTATz on Thermal Behaviors, Non-Isothermal Reaction Kinetics and Combustion Properties of DB/RDX-CMDB Propellants

Abstract

The composite double base(DB)/hexogen(RDX)-modified double base(CMDB) propellants(Nos.DB001 and CMDB100) were prepared with the lead complex of 3,6- bis(1H-1,2,3,4- tetrazol- 5- ylamino)-1,2,4,5-tetrazine(LCBTATz),with and without the ballistic modifier.Their thermal behaviors and nonisothermal decomposition reaction kinetics were investigated by thermogravimetry,derivative thermogravimetry(TG- DTG),and differential scanning calorimetry(DSC).For the LCBTATz-DB propellant,there was one mass loss stage in the TG curve and one exothermic peak in the DSC curve over the temperature range350-540 K.For LCBTATz-CMDB,there were two continuous exothermic stages in the TG curve,and only one corresponding exothermic peak in the DSC curve over the range 390-540 K.The exothermal decomposition reaction mechanisms of LCBTATz-DB and LCBTATz-CMDB follow the functions f(α)=α-1/2and f(α)=2(1-α)3/2,respectively(α:conversion degree).The self-accelerating decomposition temperatures(TSADT),thermal ignition temperatures(TTITT),critical temperatures of thermal explosion(Tb),adiabatic timesto-explosion(tTlad),and thermodynamic parameters of activation reaction were calculated,and the thermal safety was evaluated.For DB001,TSADT=444.50 K,TTITT=453.96 K,Tb=471.84 K,and tTlad=39.36 s.For CMDB100,TSADT=442.38 K,TTITT=452.89 K,Tb=464.13 K,and tTlad=21.3 s.As a high-efficiency combustion catalyst,LCBTATz in double-base propellants increases the propulsion rate and reduces the pressure index for larger scale pressures.This makes the DB propellant appear to have a significant super burning effect at 2- 8 MPa and a"mesa effect"at 8-12 MPa.Meanwhile,the pressure exponent of the CMDB propellant decreased to 0.18.