Preparation And Kinetics Of RDX/PVAc Composite Particles

Hexogen(RDX)is one of dynamites which has excellent performance and widely used in various fields.Besides,the nitramine explosives have high mechanical sensitivity,which is not conducive to charging and using.At present,materials such as insensitive agents,surfactants and high polymer are widely used to reduce the mechanical sensitivity of nitramine explosives.Polyvinyl acetate(PVAc)was used to be a coating agent to coat RDX.Meanwhile,researching the composite particle’s mechanism and influencing factors.Conclusion of study can provide or improve the theory of coating process.Based on computer simulation technology,building the composite particle model of RDX and PVAc.The molecular dynamics simulation shows that the binding energy of RDX/PVAc over 290k J/mol in the temperature range of 298K～353K.The RDX/PVAc has great compatibility;PVAc can effectively improve the mechanical properties of RDX.At the temperature of 343K,the diffusion rate of PVAc on the surface of RDX is 0.0021m~2/s,and RDX/PVAc has best mechanical properties at this temperature.In the preparation of the RDX/PVAc composite particles,the effects of temperature,stirring rate,PVAc’s concentration,PVAc’s quality and ethyl acetate’s quality are the main influencing factors during the coating process.In view of the experiment result and the molecular dynamics of the RDX/PVAc,the fact is that the stirring rate is an extremely important influence to the shape of composite particles:At the 4-speed stirring rate,particle average size is 0.45mm,and appearance of particles are uniform;in the wake of PVAc’s content increasing,the thickness of the coating layer also increasing;the temperature only affects the time of coating process;in this essay,the concentration of PVAc and the quality of ethyl acetate have not obvious effect to the shape of composite particle.Compared characterization of composite particles with RDX by FTIR,scanning electron microscopy and DSC,showing that PVAc can not affect the physical and chemical properties of the RDX.By analyzing the influence of the concentration of PVAc in coating process,the feature of this reaction is in line with zero-order reaction,which can be approximated by using the zero-order reaction equation.