Study On Thermal Behavior And Mechanical Properties Of Modified Single-base Propellant

In order to improve the static mechanical properties of the gun propellant,thermoplastic polyurethane elastomer?TPU?,ethyl cellulose?EC?,nano cellulose?CNF?and diglycerol tetranitrate?DGTN?are added as plasticizers to the propellant.A series of modified single-base propellant samples were prepared and the preparation process was determined.The effects of the types of plasticizers,DGTN content and RDX particle size in propellants containing TPU on the static mechanical properties and thermal behavior of the propellant samples were analyzed and discussed.The results of mechanical properties of propellants show that the application of plasticizers can improve the mechanical properties of the propellant.The impact strength in normal temperature of the propellant samples containing DGTN and the impact strength in high temperature of the propellant containing TPU were enhanced;the compressive strength and compression strain of the propellant containing plasticizer decreased.As the content of DGTN increases,the impact strength of the propellant increases first and then decreases,the compression resistance gradually decreases,the compression rate increases and the comprehensive mechanical properties of the propellant are better when the DGTN content is2%.When the TPU content is 1%,the impact strength of the propellant samples with different particle sizes RDX increases first and then decreases as the RDX particle size increases at low temperature,normal temperature and high temperature.When the RDX particle size is 6.47?m,the comprehensive mechanical properties are better.Thermal analysis results of propellant show that the thermal decomposition process of the propellant samples containing different plasticizers is similar,including two processes,one is the thermal decomposition of nitrocellulose,and the other is the insignificant decomposition exothermic process of guanidine.Compared with the blank sample,the addition of TPU,EC and CNF can improve the thermal stability of the propellant to a certain extent;as the content of DGTN increases,the apparent activation energy and the activation enthalpy of the propellant sample decreases,and the propellant with low DGTN content has better thermal stability than the blank sample;the thermal decomposition peak temperature of the propellant sample with a TPU content of 1%decrease as the RDX particle size increases,the thermal stability gradually increases,the apparent activation energy,activation enthalpy and activation enthalpy all increase,and the activation free energy decreases.DGTN is compatible with raw material components and can be used in propellant preparation;experimental results confirm that KH550 can coat the surface of nitroguanidine crystal;and when the concentration of KH550 is 1g·ml^-1,the preparation temperature is 35^oC and the stirring time is 4h,the coating effect is better.