• Polymer(Korea)
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• v.38 no.2
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• pp.225-231
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• 2014

The rheological properties of highly concentrated polymer bonded explosive simulant were studied by using poly(ethylene-co-vinyl acetate) with 30 and 60% vinyl acetate (VA) content as a binder, respectively. Calcium carbonate and Dechlorane, whose physical properties are similar to resarch department explosive (RDX)'s, were used as fillers. The suspensions were mixed in a batch melt mixer and it was possible to fill 75 v% at maximum. From dynamic mechanical analysis, Dechlorane showed higher interaction with binder resins than that with calcium carbonate fillers. The effects of microstructural change on the rheological properties of the suspensions were investigated by a plate-plate rheometer with constant shear rate and constant shear stress modes, respectively. The theoretical maximum packing fraction of EVA31/Dechlorane suspension obtained from Krieger-Dougherty equation was 70 v% and it was thought that 2000 Pa was proper shear stress condition for this melt processing.

• Polymer(Korea)
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• v.38 no.2
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• pp.213-219
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• 2014

The rheological characteristics of highly concentrated polymer bonded explosive simulant were studied. Hydroxyl terminated polybutadiene (HTPB) and polyethylene plastomer (Exact) were used as binders. Sugar and Dechlorane particles whose physical properties are similar to research department explosive (RDX) were used as fillers. When HTPB was used, diethyl hexyl adipate (DEHA or DOA) was used as a plasticizer together for some cases. Highly concentrated suspensions were mixed in a batch melt mixer (Rheomixer 600, Haake) and rheological properties were measured by plate-plate and capillary rheometers. Wall slip phenomena, thixotropy with shear hysteresis, and flow instability were investigated as shear rate and amount of fillers changed.

• Polymer(Korea)
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• v.38 no.3
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• pp.286-292
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• 2014

The rheology of highly concentrated polymer bonded explosive (PBX) simulant was studied. An energy material, polyethylene plastomer (Exact$^{TM}$) having similar properties to poly(BAMO-AMMO) was selected as a binder. Dechlorane with similar properties to RDX (Research Department eXplosive) was chosen as a filler. Mixing behavior in a batch melt mixer was investigated. During mixing a large amount of heat of viscous dissipation was generated and a continuous decrease in torque was observed when the filler content was above 70 v%. It was believed due to wall slip phenomena. From the SEM images, the fillers were well dispersed and the effect of mixing condition affected slightly on the dispersion. Owing to distinct shear thinning behavior of the suspensions, measuring viscosity of highly filled suspensions was possible in a high shear rate capillary rheometer though it was impossible even in a low shear rate plateplate rheometer.

• Journal of the Korea Institute of Military Science and Technology
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• v.3 no.2
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• pp.219-230
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• 2000

Plastic bonded explosive(PBX) is mainly composed of the nitramine explosives, RDX, HMX, and polymer binders. When the adhesion between nitramine crystals and binder is not particularly strong and can be failed under stress, dewetting occurs rather suddenly and this leads to a significant drop in tensile strength of explosives. Mechnical property of plastic bonded explosive depends on the surface characteristics of filler and binder. In order to design for better adhesion, an understanding of the surface properties of explosive and binder is essential. In this study, 2 kinds of RDX and 4 kinds of ethylene vinyl acetate copolymers are selected, since they are widely used in many plastic bonded explosives. The technical objective of this investigation is to calculate for the surface free energy of RDX and EVA using theory of Fowkes, van Oss, Neumann approaches and Kaelble equation and to predict the interaction between filler and binder from their surface free energies.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.2
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• pp.109-115
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• 2008

A Plastic Bonded Explosive(PBX) is mainly composed of nitramine explosive and polymer binder. The great number of serious applications of PBX requires the good adhesion between nitramine crystals and binder, which depends on the surface characteristics of a filler and binder. In the pursuit of the better design to achieve the enhanced adhesion, profound knowledge of the surface and interfacial characteristics of explosive and binder should be exploited. In this study, the influences of physicochemical properties between RDX and binders such as interfacial tension($\gamma_{SL}$), latent heat($Q_m$), and density($\rho$) on impact sensitivity of PBX were investigated. As experimental results, the major contribution factor to impact sensitivity of PBX was the interfacial tension, compare with other surface properties. The correlation coefficient of $H_{50}$ versus $\gamma_{SL}$ is 0.9932 when a polynomial regression method was used.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.4
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• pp.96-106
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• 2017

In pressable polymer bonded explosives (PBXs), densification occurs due to rearrangement and deformation of explosive particles during pressing. If brittle explosives are compressed till particle fraction become higher than theoretical random close packing fraction (RCPF), bigger particles should be fractured to fill the void. In this study, multi-modal particle system was introduced for the decrease in possibility of particle fracture during compression expecting decrease in shock sensitivity of highly filled pressable PBX. The experimental results showed the trimodal particle system had low sensitivity with high density, compared to bimodal particle system.

• Polymer(Korea)
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• v.38 no.4
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• pp.417-424
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• 2014

Reactivity and rheological behavior of highly concentrated polymer bonded explosives (PBX) simulant was studied. As a binder, thermosetting hydroxyl terminated polybutadiene (HTPB) was used. By using bimodal $CaCO_3$ (size ratio 10:1) and sugar particles (size ratio 25:1) as fillers, maximum 75 v% filling was possible during melt mixing. The relative viscosities of bimodal suspension were much lower than those of unimodal one and showed minimum values at 0.25 of fine particle fraction. In curing experiment, as curing temperature increased, the time of initiation and completeness of curing reaction became shortened, the torque kept low, and the change of internal temperature decreased.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.441-444
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• 2011

Type A and Type B and are commercial HTPB models, which are very popular prepolymer for polyurethane binder family. So the study has been performed on the physical, chemical characteristic of HTPB and viscosity, mechanical property of PBX-A applying to HTPB. But We excluded the Type A from Appication test, because of law Hydroxyl value. And in the case of Type B, Type B-1, 2 has mechanical disadvatage to apply to HTPB in the process comparing with B-3. It seems to make no problem if we change equivalence ratio or curing condition within standards. But if we are to apply process condition like R-45HT(US-sample), it would be essential to apply HTPB with higher Hydroxyl Value and hydroxyl Functionality.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.3 s.18
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• pp.129-139
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• 2004

DXD-19 is a flexible sheet explosive, which is a new polymer-bonded explosives(PBX's). DXD-19 is relatively insensitive and can be extruded into various configurations to be applied to munitions. A typical application includes multi-point initiation for the warhead, cutting/severance devices and transfer lines. The DXD-19 composition employs a binder system derived from the thermoplastic elastomer(HyTemp 4454) containing $5\%$ OH terminated with isocyanate curable for increasing mechanical properties. The use of an elastomer CAB increases its mechanical properties and the use of an energetic plasticizer BDNPF/BDNPA(F/A) improves the process ability as well as energy contents. The composition of the extruded DXD-19 formulation is formed $\%$ weight of $PETN/HyTemp/ATEC/(F/A)/CAB=72\~73/12\~13/6\~7/6\~7/1\~2$. Our safety tests of DXD-19 shows Insensitivity to an impact test and friction test, good thermal stability and excellent mechanical properties.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.6
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• pp.844-852
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• 2014

PBX simulant is known to exhibit highly nonlinear behaviors of deformation such as the stress softening, hysteresis under cyclic loading, residual strain after unloading, and aging. This paper proposes a new pseudo-elastic model for PBX simulant considering stress softening and residual strain. Uniaxial loading and unloading tests at quasi-static states were carried out in order to obtain the mechanical properties of the PBX simulants. And then the Dorfmann-Ogden model is modified to make it consistent with the test result of PBX simulants. Prediction with the new model shows a good correspondence to the experimental data demonstrating that the model properly describes stress softening and residual strain of PBX simulants.