Comparing the Effectiveness of DHE and PEG 600 Additives on the Tensile Mechanical Properties of Flexible Sheet Explosive Based on RDX and HTPB

Flexible sheet explosive is a plastic bonded explosive (PBX) based on hydroxyl-terminated polybutadiene (HTPB), isophorone diisocyanate (IPDI) curing agent, cyclotrimethylenetrinitramine explosive (RDX), dioctyl adipate plasticizer (DOA) and diethylol dimethylhydantoin (DHE) bonding agent. In this research, the effect of polyethylene glycol-600 (PEG-600) chain extender additive compared to DHE bonding agent on some mechanical properties of product such as tensile strength and shore A hardness has been investigated. For this purpose, different formulations containing PEG-600 or DHE additives were prepared and various production conditions including different amounts of additives and the molar ratio of isocyanate to hydroxyl group were optimized and quality of samples were evaluated from the perspective of various mechanical and safety characteristics. Also, the completion of the polyurethane reaction and the presence of excess IPDI were monitored using the attenuated total reflectance infrared spectroscopy (ATR-IR) method. The final results in optimal conditions showed that by using of DHE or PEG-600 in the PBX formulation, the ultimate tensile strength and the yield strength of the material in the presence of two additives are close to each other and at least twice that of PBX without additive. Also, the shore A hardness is also decreases from 39 to 31 and 32, respectively. The additive-free material is a flexible elastomer with more plastic behavior, and by using chain extender or bonding agent, its stress-strain behavior approaches to semi-ductile mode. The results of this research can be used to replace the expensive substance of DHE with cheap, domestically produced PEG-600 polymer in the formulation of flexible sheet explosives.