Study On The Construction And Basic Application Of Graphene Materials Modified Energetic Composites

Due to its good electrical and thermal conductivity and excellent mechanical properties,graphene materials（graphene,graphene oxide and functionalized graphene）could be used as addition in energetic materials.Because they can reduce the sensitivity of high-energy explosives,improve the thermal decomposition performance and enhance the mechanical properties of the energetic system.This paper prepared graphene materials,and then applied them as modifiers in energetic polymers,explosive particles,and energetic inks,respectively.The effects of graphene materials to three kinds of compounds are studied,and the details are as follows:There were two methods used to prepare graphene in this article,which were chemical method and detonation synthesis method.Firstly,graphite oxide（GIO）was prepared by Hummers method using flake graphite（FG）as the raw material.The effect of different drying methods on the target product graphene oxide（GO）was studied,and the optimum process conditions for preparing GO was obtained.Meanwhile,the reduced graphene oxide（rGO）was prepared by reducing of GO with reducing agent.Second,calcium carbonate as the carbon source,magnesium powder as the reducing agent,and waste explosives in the laboratory as the main charge,a few layers of graphene was successfully synthesized by detonation synthesis method,and the forming mechanism of graphene prepared by the explosion method was proposed.By comparing two methods for preparing graphene,we found that although the detonation synthesis method could obtain few graphene layers,the synthesized graphene molecules lack the functional groups,which was not conducive to subsequent research and application;while the redox method could not only obtain graphene,but also obtain graphene oxide with high yield.Graphene oxide was rich in oxygen-containing functional groups and very suitable as a modified precursor.As the graphene materials in the subsequent research were required to be dispersed in organic solvents or substrates.Therefore,the following applications of this subject were all using graphene materials（graphene oxide and graphene）obtained by the redox method.（i）To improve mechanical properties of Glycidyl azide polymer（GAP）,based on the excellent characteristics of graphene,graphene material was used as modifier,GAP-based energetic thermoplastic elastomers（ETPE）were synthesized.First,the hydroxylated graphene(GO_-OH)was prepared via hydroxylation using butylamine as modification,GO as raw material.Then,GO_-OH as cross-linking agent,TDI as curing agent,and T₁₂ as catalyst,GO_-OHOH crosslinking-modified GAP-based ETPE were synthesized,labeled ETPEGO_-OH,and the synthetic process conditions were studied.The mechanical properties,morphologies,structure,molecular weight,glass transition temperature(T_gs)and thermal decomposition of the elastomer were characterized and tested by universal testing machine,scanning electron microscopy（SEM）,fourier transform infrared（FTIR）,gel permeation chromatography（GPC）,and differential scanning calorimetry（DSC）.The results shown that when the R value was 1.4,the curing temperature was 65°C,and the amount of GO_-OH added was 0.5%,the mechanical property of the obtained elastomer was the best,and its tensile strength（σ_b）was 1.29 MPa,and the elongation at break（ε_b）was 388%.Compared with that of pure ETPE,the number-average molecular weight（M_n）of ETPE_GO-OH-0.5 increased from 16150 to 17533,the polydispersity coefficient（PDI）increased from 1.87 to 2.03,the glass transition temperature increased from-35.8°C to-34.5°C,and the melting point increased from 130°C to 140°C.The thermal stability of the ETPE_GO-OH elastomer was lower than that of the pure ETPE.When the amount of GO_-OH is 1%,the thermal stability was the worst.Therefore,the amount of GO_-OH cannot exceed 1%.The surface of HMX was coated by the above-mentioned synthetic elastomer as the binder,and the morphology,phase,thermal decomposition properties and impact sensitivity of the composite particles was characterized and tested.The results showed that the synthesized ETPE_GO-OH-0.5 elastomer could be used as an energetic binder to coat HMX.ETPE_GO-OH elastomer could form a dense protective film on the surface of HMX,which could significantly improve the thermal stability and reduce the impact sensitivity of HMX.（ii）Inordertoobtainlow-sensitivityandsmall-sizeε-CL-20（Hexanitrohexaazaisowurtzitane）,a series of submicron CL-20/GO energetic composite particles were prepared by mechanical-chemical method.The morphology,particle size,crystal form,component content,thermal decomposition property and impact sensitivity of the prepared composite particles were characterized and tested.The results showed that the CL-20/GO composites prepared by the mechanical-chemical method were spherical,the size was about 140 nm,and the crystal form wasε-form.Thermal analysis results showed that GO could improve the thermal stability of CL-20;The impact sensitivity results showed that the impact sensitivity of CL-20/GO submicron-sized energetic composite particles was reduced significantly;The mechanical sensitivity of CL-20 could be controlled by adjusting the amount of GO.（iii）In order to meet the requirements of high-precision and dexterity in the development of smart weapon systems,a new type of energetic ink formulation was designed in this study.This formula was suitable for micro direct writing deposition charges.Through the selection of the main explosives,binders and modifiers,this study used submicron CL-20as the main explosive and the binary system consisting of GAP and EC as the binder and graphene as the modifier to formulate the ink.According to the viscosity and the effect of ink molding,the mass fraction of EC-ethanol system was 8%;According to the theoretical detonation velocity,charge density,and viscosity,the solid content of CL-20 was 90%;According to the measured viscosity of different proportion between GAP and EC,and with principle of highest energy,the retio of GAP and EC was 3:2.The microstructure and morphology of the ink after molding were characterized,and the results showed that there were no fissures observed in forming ink when the amount of graphene was 1%and the CL-20 particles were uniformly dispersed in the bonding system;XRD results showed that CL-20 didn’t transform crystal during the ink formulation process and still maintainedεform.Through the tests of DSC,detonation performance and safety performance,it was found that the prepared energetic ink had a good thermal stability.The detonation of all of the formulation was over 7500 m/s.When the amount of graphene was 1%,the critical dimesion was 132μm and the special height was 86.8 cm.