Influence Of Binder On Properties Of HMX-based PBX

HMX（Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine）,as a comprehensive and well-researched high-energy explosive,is known for its high density,high energy and excellent thermal stability,but due to its own high sensitivity,Polymer Bonded Explosive（PBX）needs to be prepared by adding inert additives such as Polymer binder to meet the requirements in practical application.Polymer binders play an important role in PBX for component bonding,performance improvement and molding process,and improve the safety of mixed explosives to a certain extent.At the same time,there are many types of polymer binders with different properties.Therefore,they have different effects on the performance of polymer bonded explosive.In this paper,HMX-based polymer-bonded explosives with different binder types were prepared by solution-water suspension method,and the influence of binder on the performance of HMX-based PBX and the influence of process factors on the coating effect of modeling powder particles were systematically investigated.The main research contents are as follows.（1）In this study,a total of seven kinds of polymers,including fluoroelastomer F2602,F2463,F2311,fluorine resin F2314,acrylate rubber ACM AR-71,ethylene vinyl acetate copolymer EVA-40 W,and thermoplastic polyurethane Estane5703,were selected as binders.to prepare HMX-based PBX modeling powders by solution-water suspension method.The optimal process conditions for the coating of HMX with the seven binders were determined by studying the effects of process conditions such as material-liquid ratio,stirring speed,temperature,binder concentration and surfactant on the coating effect of modeling powder particles by single-factor experimental method.（2）The properties of the seven polymer-bonded explosives obtained under the optimum preparation process conditions were tested and characterized.The SEM morphological characterization showed that the seven HMX-based PBX modeling powder particles were spherical,with uniform particle size and dense surface;the X-ray diffraction（XRD）tests showed that the HMX crystalline shape did not change before and after coating;the differential scanning calorimetry（DSC）tests showed that different types of binders had different degrees of influence on the thermal properties of HMX-based PBX,among which fluoroelastomer F2602 showed the best thermal stability and the apparent activation energy increased by 31.73 KJ/mol compared with that of raw HMX;the impact sensitivity and friction sensitivity tests showed that the mechanical sensitivity of HMX is reduced to a certain extent by seven binders.Among them,fluoroelastomer F2463 has an obvious passivation effect on HMX’s impact sensitivity,and the impact energy is increased from 6 J to 13 J through the molded powder particles coated by fluoroelastomer F2463;the friction sensitivity of HMX was improved significantly by fluoroelastomer F2602 and polyurethane Estane5703,which increases the friction load of the modeling powder particles coated from 84 N to 216 N.The static compression mechanical properties test showed that HMX/Estane5703 polymer bonded explosive column showed the strongest compression resistance,the compressive strength reaches 19.93 Mpa.（3）In this paper,the effects of binder type and surfactant on the response characteristics of HMX-based PBX were studied by using binder type and surfactant as variables with the cook-off experiment.The results showed that the reaction degree of HMX-based PBX was relatively weak when polyurethane Estane 5703 was used as the binder under the condition of no surfactant,and the reaction degree of HMX-based PBX was relatively weak when fluoroelastomer F2311 was used as the binder under the condition of surfactant.Meanwhile,the surfactant had an effect on the strength of the reaction degree of HMX-based PBX with three fluoropolymers F2602,F2311 and F2314 as binders.