Study On The Influence Of Phenolamine Coupling Agents On The Properties Of HMX-based PBX Explosives

Cyclotetramethyltetranitamine（HMX）has high density,high explosive speed,and good detonation performance.It is widely used in the main medicine,explosive initiation device and solid propellant of high-energy explosives.However,because HMX itself is sensitive to external impact and friction reaction,there are certain risks in the use of new explosives and propellants,which limits its application.Therefore,it is of great significance for the practical application of HMX in weapons and ammunition to use polymer materials for coating modification to improve the safety and reliability of HMX.In this paper,based on the Self-poly-attachment properties based on the polydopamine coating/particles,the HMX was surface-coated and prepared with the phenolamine coupling agents dopamine,tannic acid and levodopa.The morphology and structure of composite materials were tested by scanning electron microscope（SEM）,Fourier infrared spectroscopy（FT-IR）,Raman spectroscopy（Raman）,X-ray photoelectron spectrometer（XPS）,differential scanning calorimeter（DSC）,universal tester,mechanical sensitivity,thermal stability and mechanical properties.According to the mechanism of explosive and hotspot theory,the effects of reaction time,water bath temperature and stirring rate on the complex are analyzed.The thermal stability of the complex and its mechanical properties are investigated under optimal parameters.The results show that the order of influence of various factors on sensitivity of HMX coated with dopamine is:reaction time>water bath temperature>stirring rate.The optimal process was the reaction time of 9 h,the water bath temperature of 25℃,and the stirring rate of 200～300 r/min.Under the best parameter,the impact sensitivity H₅₀is 52 cm,the explosion probability of friction sensitivity is 12%,the critical temperature of thermal explosion is280.0℃;the order of influence of various factors on sensitivity of HMX coated with tannic acid is:the ratio of tannic acid to Fe³⁺3:1>water bath temperature>stirring rate.The best process is the ratio of tannic acid to Fe³⁺is 3:1,the water bath temperature is 25℃,the stirring rate is 200～300 r/min,and the hot burst critical temperature is 281.1℃.Under the optimal parameter,H₅₀is 53 cm,and the explosion probability of friction sensitivity is 12%;the order of influence of various factors on sensitivity of HMX coated with L-dopa is:reaction time>water bath temperature>stirring rate.The optimal process was a reaction time of 12 h,water bath temperature of 25℃and stirring rate of 300 r/min.The impact sensitivity H₅₀is 52 cm,the explosion probability of friction sensitivity is 12%,and the thermal burst critical temperature is 279.3℃.Finally,fluorine rubber F₂₆₀₄binder is used for mechanical testing.The compressive strength of PBX（HMX）is 3.03 MPa,PBX（HMX@PDA）is 15.05 MPa,PBX（HMX@MPN）is 24.28 MPa,PBX（HMX@PL-DA）is 7.81 MPa.According to the experimental data,the performance modification effect of three phenolamine coupling agents on HMX is:tannic acid>dopamine>L-dopa.Because the phenolamine coupling agent layer has a rich hydroxyl group as a hydrogen donor,it is easy to react with fluorine atoms to form hydrogen bonds,the combined effect of mechanical interlocking and interfacial hydrogen bonds improves the interfacial interaction between HMX and fluoropolymers and improves the mechanical properties of the composite.