Adiabatic self heating and isothermal heat generation rate of rocket propellant formulations containing ε-HNIW (ε-CL20) and GAP binder

摘要

Formulations based on high energy ingredients have the potential to become propellants for high velocity rockets. Seven formulations have been investigated and the main ingredients are binder GAP (glycidyl azide polymer, bonded with Desmodur? N100), 42 to 47 mass-% ε- CL20 (ε-HNIW, Hexanitrohexazaisowurtzitane), 20 mass-% AP (ammonium perchlorate) and the energetic plasticizers GAP-A, TMETN, BTTN in varying amounts. Ageing and thermal decomposition behaviour are questions to be answered for such mixtures. From isothermal heat generation rate, measured with a microcalorimeter of type TAM? (Thermal Activity Monitor), an unexpected course was found by the temperature change from 80°C to 89°C. At 89°C an endothermal peak occurred not present at 80°C. Adiabatic self heating measured with an ARCTM (Accelerating rate Calorimeter) reveals a different behaviour in this series of seven samples. One group contains as plasticizer only TMETN whereas the other one has GAP-A in addition. The deflagration points and the courses of the adiabatic exotherms differ between these two groups of formulations. The group with GAP-A shows a retardation of the adiabatic self heat rate h between 160 und 175°C. The temperatures of the minima in h show an analogous correlation with GAP-A or TMETN content as do the times to minima in heat generation rate at 89°C. The way to model adiabatic self heat rate truncated by deflagration is shown.