This work describes thermal decomposition behaviour of plastic bonded explosives(PBXs) based on mixture of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX) and 2,4,6-triamino-1,3,5-trinitrobenzene(TATB)with Viton A as poly...This work describes thermal decomposition behaviour of plastic bonded explosives(PBXs) based on mixture of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX) and 2,4,6-triamino-1,3,5-trinitrobenzene(TATB)with Viton A as polymer binder. Thermal decomposition of PBXs was undertaken by applying simultaneous thermal analysis(STA) and differential scanning calorimetry(DSC) to investigate influence of the HMX amount on thermal behavior and its kinetics. Thermogravimetric analysis(TGA) indicated that the thermal decomposition of PBXs based on mixture of HMX and TATB was occurred in a three-steps. The first step was mainly due to decomposition of HMX. The second step was ascribed due to decomposition of TATB, while the third step was occurred due to decomposition of the polymer matrices. The thermal decomposition % was increased with increasing HMX amount. The kinetics related to thermal decomposition were investigated under non-isothermal for a single heating rate measurement. The variation in the activation energy of PBXs based on mixture of HMX and TATB was observed with varying the HMX amount. The kinetics from the results of TGA data at various heating rates under non-isothermal conditions were also calculated by Flynn—Wall—Ozawa(FWO) and Kissinger-Akahira-Sunose(KAS)methods. The activation energies calculated by employing FWO method were very close to those obtained by KAS method. The mean activation energy calculated by FWO and KAS methods was also a good agreement with the activation energy obtained from single heating rate measurement in the first step decomposition.展开更多
The X-ray diffractive technology was adopted for tentative study of plastic bonded explosive.The datum of some new diffractive peaks in standard PDF cards were added.The effects of strain to interplanar distance and c...The X-ray diffractive technology was adopted for tentative study of plastic bonded explosive.The datum of some new diffractive peaks in standard PDF cards were added.The effects of strain to interplanar distance and crystal size of the explosive were studied.The results show that grain size of plastic bonded explosive is decreasing with the increasing of the pressure,and the residual stress of the explosive is draw stress.展开更多
The microstmcture evolution of plastic-bonded explosives （PBXs） after thermal stimulus plays a key role in PBX performance. In this paper, the nanoscale pores of thermal-treated octahydro-1,3,5,7-tetranitro-1,3,5,7 ...The microstmcture evolution of plastic-bonded explosives （PBXs） after thermal stimulus plays a key role in PBX performance. In this paper, the nanoscale pores of thermal-treated octahydro-1,3,5,7-tetranitro-1,3,5,7 tetrazocine （HMX）- based PBXs with different HMX particle sizes [approximately 40 （FLIP） and 100 μm （LHP）] were measured using small- angle X-ray scattering （SAXS）. No obvious pore variations were found in the LHP samples heated at 160 ℃ for 6 h, whereas the amount of pores of FHP decreased when subjected to 160 ℃ for 6 h. At 180 ℃, the average pore radii of FHP and LHP decreased from approximately 45 nm to 25 nm, and the total pore volume increased distinctively because of phase transformation. The LHP sample reached a high level of pore content after being held at 180 ℃ for 1 h, whereas FHP required 3 h. Both FHP and LHP had relatively high pore volumes when subjected to 200 ℃ for 1 and 3 h.展开更多
Use of epoxy as an adhesive is a common practice. The most common applications are permanent sealants. Epoxies have a wide range of operating temperatures, and are very resistance to adhesive failure. When a need to r...Use of epoxy as an adhesive is a common practice. The most common applications are permanent sealants. Epoxies have a wide range of operating temperatures, and are very resistance to adhesive failure. When a need to remove this adhesive arises, it is not always easily accomplished especially if the part has excessive adhesive. To maintain fidelity of the parts attached by epoxy, a project evaluating several methods of epoxy removal was conducted. Methods evaluated included low wavelength, near-ultraviolet radiation, solvent dissolution, and thermal cycling. The UV method failed to demonstrate a repeatable dissociation. The solvent study did result in dissociation of bonds, but introduced chemicals that could make subsequent chemical analysis of parts suspect. Thermal cycling showed a high repeatability for dissociation of bonds and may prove to be relatively inexpensive to implement.展开更多
基金DRDO(TBR-1251)for funding and awarding the Project
文摘This work describes thermal decomposition behaviour of plastic bonded explosives(PBXs) based on mixture of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX) and 2,4,6-triamino-1,3,5-trinitrobenzene(TATB)with Viton A as polymer binder. Thermal decomposition of PBXs was undertaken by applying simultaneous thermal analysis(STA) and differential scanning calorimetry(DSC) to investigate influence of the HMX amount on thermal behavior and its kinetics. Thermogravimetric analysis(TGA) indicated that the thermal decomposition of PBXs based on mixture of HMX and TATB was occurred in a three-steps. The first step was mainly due to decomposition of HMX. The second step was ascribed due to decomposition of TATB, while the third step was occurred due to decomposition of the polymer matrices. The thermal decomposition % was increased with increasing HMX amount. The kinetics related to thermal decomposition were investigated under non-isothermal for a single heating rate measurement. The variation in the activation energy of PBXs based on mixture of HMX and TATB was observed with varying the HMX amount. The kinetics from the results of TGA data at various heating rates under non-isothermal conditions were also calculated by Flynn—Wall—Ozawa(FWO) and Kissinger-Akahira-Sunose(KAS)methods. The activation energies calculated by employing FWO method were very close to those obtained by KAS method. The mean activation energy calculated by FWO and KAS methods was also a good agreement with the activation energy obtained from single heating rate measurement in the first step decomposition.
文摘The X-ray diffractive technology was adopted for tentative study of plastic bonded explosive.The datum of some new diffractive peaks in standard PDF cards were added.The effects of strain to interplanar distance and crystal size of the explosive were studied.The results show that grain size of plastic bonded explosive is decreasing with the increasing of the pressure,and the residual stress of the explosive is draw stress.
基金supported by the National Natural Science Foundation of China(Grant Nos.11205137,11079043,and 11302199)
文摘The microstmcture evolution of plastic-bonded explosives （PBXs） after thermal stimulus plays a key role in PBX performance. In this paper, the nanoscale pores of thermal-treated octahydro-1,3,5,7-tetranitro-1,3,5,7 tetrazocine （HMX）- based PBXs with different HMX particle sizes [approximately 40 （FLIP） and 100 μm （LHP）] were measured using small- angle X-ray scattering （SAXS）. No obvious pore variations were found in the LHP samples heated at 160 ℃ for 6 h, whereas the amount of pores of FHP decreased when subjected to 160 ℃ for 6 h. At 180 ℃, the average pore radii of FHP and LHP decreased from approximately 45 nm to 25 nm, and the total pore volume increased distinctively because of phase transformation. The LHP sample reached a high level of pore content after being held at 180 ℃ for 1 h, whereas FHP required 3 h. Both FHP and LHP had relatively high pore volumes when subjected to 200 ℃ for 1 and 3 h.
文摘Use of epoxy as an adhesive is a common practice. The most common applications are permanent sealants. Epoxies have a wide range of operating temperatures, and are very resistance to adhesive failure. When a need to remove this adhesive arises, it is not always easily accomplished especially if the part has excessive adhesive. To maintain fidelity of the parts attached by epoxy, a project evaluating several methods of epoxy removal was conducted. Methods evaluated included low wavelength, near-ultraviolet radiation, solvent dissolution, and thermal cycling. The UV method failed to demonstrate a repeatable dissociation. The solvent study did result in dissociation of bonds, but introduced chemicals that could make subsequent chemical analysis of parts suspect. Thermal cycling showed a high repeatability for dissociation of bonds and may prove to be relatively inexpensive to implement.
