Synthesis Of Energetic Thermoplastic Elastomer And Its Application In Gun Propellants

In order to study the preparation technology and application of propellants used energetic thermoplastic elastomer (ETPE), the synthesis experimental study of ETPE was carried on through ETPE structural analysis and molecular design. The ETPEs with four different chain extenders were synthesized and the structure, morphology and properties of ETPEs were studied. Application performance study was carried on using the GAP-BDO based ETPE which had better comprehensive performance as the binder, and the preparation conditions of high solid content ETPE based propellants was explored, the energy, mechanical property and combustion property of the test samples were studied. The main results of the study as follows:The GAP based ETPEs were systhesised using the polyether polyol GAP as the soft segment, the diisocyanate MDI which has symmetrical structure and rigid benzene as the basic hard segment and dihydric alcohol which has even number of -CH2- in its molecular chain as chain extender. The basic synthesis process conditions of melt-prepolymerization method as follows:The isocyanate index (R) is 0.98, the content of hard segment is 35%, the catalyst concentration is 0.6‰; The prepolymerization temperature is 85℃ and the prepolymerization reaction time is 2h; The chain extender is added in constant speed, the chain extension reaction temperature is 60 ℃, the chain extension reaction time is about 10 to 15 minutes, aging time is 30℃ for 1 day and 90℃ for 3 days,The GAP based ETPEs that with four different chain extenders all have the same polyurethane structure and a certain degree of microphase separation, and the number average molecular weigh betweens 20000 to 65000, the thermal decomposition temperature at about 250 ℃ and the thermal stability obviously improves than GAP prepolymer. The ETPE using BDO as chain extender has good comprehensive performance. It has good mechanical properties, moderate softening point, good solubility and low glass transition temperature (Tg).According to above study, the preparation technology of high solid content ETPE based propellants was studied using the GAP-BDO based ETPE as binder and RDX as high-energy oxidizer. The preparation condition of propellants is 0.3 solvent ratio,50 ℃ kneading temperature,2h kneading time and 60 ℃ molding temperature. The quality of obtained propellant sample is good, the combustion curve is smooth, the change rule of burning rate at different temperatures is normal, the burning rate pressure coefficient is small and pressure exponent of propellant is big. Compared with the existing GAP-THF based ETPE adhesives, the GAP-BDO based ETPE adhesives contribute to the energy of propellant larger, the combustion performance is stable and the mechanical properties of the two samples are similar.