Rheological Properties of DNAN/HMX Melt-cast Explosives: Maximum Packing Density Calculation and Modified Viscosity Model

： To explore the influence rule of octogen （ HMX ） solid content ， system temperature ， HMX particle size ， HMX particle gradation and functional additives etc.on the rheological properties of 2 ， 4⁃dinitroanisole （ DNAN ） /HMX suspensions ， the appar⁃ ent viscosity of DNAN/HMX suspensions under different material state conditions was investigated by a digital viscometer. Re⁃ sults show that the suspension presents Newtonian fluid characteristics when the solid content is 3%. Apparent viscosity of the suspension can be described with Ostwald⁃deWaele model when the HMX solid content is 12%-30% ， and the value of non⁃ Newton index n is decreased from 0.842 to 0.374. The influence of temperture on the apparent viscosity can be described by the Arrhenius equation when the temperture is in the range of 95-116 ℃ ， and the activation energy E a increases from 25.97 kJ ∙ mol -1 to 30.17 kJ ∙ mol -1 . The apparent viscosity decrases as the particle size increases. When the particle gradation ratio of 999.5 μ m particle size to 132.6 μ m is 2 ∶ 1 ， the apparent viscosity reaches the minimum and the solid content is up to 80%. Functional ad⁃ ditives N ⁃methyl⁃4⁃nitroaniline （ MNA ） and tri （ β chloroethyl ） phosphate （ CEF ） make the apparent viscosity of the suspensions decrease ， while dehydrated sorbitol monostearate polyoxyethylene ether （ Tween 60 ）， microcrystalline wax⁃80 （ MV80 ）， cellu⁃ lose acetate butyrate （ CAB ）， and thermoplastic polyurethane -5720 （ TPU 5720 ） make the the apparent viscosity of the suspen⁃ sions increase.