Synthesis, Characterization and Properties of Nitropolybutadiene as Energetic Plasticizer for NHTPB Binder

Abstract

The nitration of low molecular weight polybutadiene (PB) by a convenient and inexpensive procedure was investigated. To retain the unique physico‐chemical properties of the plasticizer, it was nitrated to an extent of 10 % double bonds. The product nitropolybutadiene (NPB) was characterized by FT‐IR and 1H NMR spectroscopy as well as GPC, DSC, and TGA methods. The kinetic parameters for the decomposition of NPB from room temperature to 400 °C were obtained from non‐isothermal DSC. The changes in glass transition temperature (Tg) and inert uncured binder systems were used for determination of its efficiency as plasticizer. NPB was used in cured and unfilled nitro‐hydroxyl terminated polybutadiene (NHTPB) binder. Isothermal thermogravimetric analysis (Iso‐TGA) was employed to determine the migration rate in cured and unfilled HTPB binder systems compared to the dioctyladiphate (DOA) plasticizer. It was found that the exudation of the NPB plasticizer is slower than that of the DOA plasticizer. Thus, the NHTPB/NPB binder system (binder/plasticizer) presents more convenient mechanical properties than HTPB/DOA and is a promising new energetic binder system for polymer bonded explosives.

Azido‐terminated Hyperbranched Multi‐arm Copolymer as Energetic Macromolecular Plasticizer

“…Correlating further, the plasticizer efficiency (e) can be described as Eq. (9). These results are listed in Table 4.…”

“…Simple glass transition theory for two component system (binder and plasticizer) is based on Eq. (8) [9].…”

“…The use of energetic oligomers as plasticizers is a good strategy and approach due to their low volatility and mobility, low glass transition temperature, excellent migration resistance, high energy and insensitivity. [1,9].Consequently, low mol wt (400-700 g mol À1 ) glycidyl azide polymer (GAP), ester-terminated glycidyl azide polymer (GAPE), azido-terminated glycidyl azide polymer (GAPA) and glycidyl nitrate polymer (polyGLYN) have been used in GAP, PET and PGN binder systems as energetic oligomer plasticizers [10][11][12][13][14]. In general, there is an inverse correlation between molecular weight and plasticizer mobility: the larger the molecule, the slower it will exude through the matrix [9].…”

“…[1,9].Consequently, low mol wt (400-700 g mol À1 ) glycidyl azide polymer (GAP), ester-terminated glycidyl azide polymer (GAPE), azido-terminated glycidyl azide polymer (GAPA) and glycidyl nitrate polymer (polyGLYN) have been used in GAP, PET and PGN binder systems as energetic oligomer plasticizers [10][11][12][13][14]. In general, there is an inverse correlation between molecular weight and plasticizer mobility: the larger the molecule, the slower it will exude through the matrix [9]. Nevertheless, linear polymers with higher molecular weight are more viscous in nature, so plasticizers with molecular weight in the range of 400-1000 g mol À1 are preferred [1].…”

Hydroxyl Terminated Polybutadiene: Chemical Modification and Application of these Modifiers in Propellants and Explosives

“…Meanwhile, nitro-HTPB-2 based propellants just gave a small increase, but still remained in the safety range according to the tests for impact and friction sensitivity. Additionally, another application of cured and unfilled nitro-HTPB-2 based elastomer, using nitro-polybutadiene as an energetic plasticizer, was reported by Ashrafi et al [71]. Compared with the HTPB/DOA system, nitro-HTPB-2/nitro-polybutadiene exhibited lower migration rates because of the similarity in structure between these two polybutadiene based polymers, and this new binder system can not only enhance the energetic properties but also possess good mechanical properties.…”